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Chapter 95 – Orbital Diseases

Chapter 95 – Orbital Diseases

 

JONATHAN J. DUTTON

 

 

 

 

 

DEFINITION

• The orbit is the bony cavity that contains the eye, eye muscles, lacrimal gland, and neural and vascular structures that serve eye function. Numerous diseases occur in the orbit that can affect visual function.

 

KEY FEATURES

• A mass lesion of the orbit may cause proptosis or displacement of the eye.

• Orbital lesions may be the presenting sign of systemic diseases, such as metastatic cancer.

• Demographics such as age, sex, and location within the orbit may be helpful in making a specific diagnosis.

• Treatment of orbital lesions may be medical, such as the use of steroids or radiotherapy for inflammatory disease, and does not always require surgery.

 

 

 

INTRODUCTION

During the past few decades, advances in diagnostic instrumentation and surgical technique have helped elevate the orbit to an anatomical area of great clinical interest. Computed tomography, magnetic resonance imaging (MRI), and orbital echography have dramatically improved diagnostic accuracy and allow more careful therapeutic planning. Orbital surgery has become safer and more precise, and treatment results are significantly enhanced. The operating microscope, specialized orbital instruments, fiberoptic illumination, endoscopy, and hypotensive anesthesia have allowed orbital surgeons to perform complex, deep dissections more easily and with fewer complications.

CLINICAL EVALUATION

The initial step in the evaluation of orbital disease is a complete ophthalmic examination.[1] A careful medical and ophthalmic history, including time course of the disease, past trauma, ocular surgery, and systemic illnesses, must be obtained. A complete clinical examination includes assessment of visual acuity and visual fields, anterior and posterior segment evaluation, and external and periorbital inspection. The use of modern imaging techniques is almost always indicated—the choice depends on the disease processes suspected.

In this chapter, the most common orbital lesions are categorized by diagnostic criteria, to enable the reader to evaluate patients more easily and establish a meaningful differential diagnosis ( Tables 95-1–95-3 ).[1] [2] In addition, the key points and diagnostic criteria for each lesion are given.

 

 

TABLE 95-1 — FREQUENCY OF ORBITAL LESIONS BY MAJOR DIAGNOSTIC GROUP

Diagnostic Group

Frequency (%)

Thyroid orbitopathy

50

Cystic lesions

10

Inflammatory lesions

11

Vascular neoplasms

4

Vascular, structural

1

Lacrimal gland lesions

2

Lymphoproliferative lesions

5

Secondary tumors

4

Mesenchymal lesions

4

Metastatic tumors

2

Optic nerve tumors

3

Other and unclassified

5

(Data from Dutton JJ, Frazier Byrne S, Proia A. Diagnostic atlas of orbital diseases. Philadelphia: WB Saunders; 2000:1–5.)

 

 

METASTATIC TUMORS

Metastatic tumors represent 2–3% of all orbital tumors. In 30–60% of patients, orbital metastases develop before the diagnosis of the primary tumor ( Table 95-4 ). Metastases reach the orbit via hematogenous spread and occur less commonly than do uveal metastases. In adults, most metastases are carcinomas. In children, metastases are more likely to be sarcomas and embryonal tumors of neural origin. Only 4% of orbital metastases are bilateral. Clinical symptoms include proptosis, axial displacement of the globe, ptosis, diplopia, pain, and chemosis.

Metastatic Carcinoma

KEY POINTS.

The most common primary sites of metastatic carcinoma to the orbit are the breast, lung, prostate, gastrointestinal tract, and kidney. [3] [4] [5] Key features are:

• For breast carcinoma, the interval from primary diagnosis to orbital metastasis is 3–5 years.

• In scirrhous cell breast carcinoma and gastric carcinoma, enophthalmos may result from orbital fibrosis.

• Metastatic lung cancer is seen most commonly in smoking males aged 45–60 years.

• Prostatic metastases occur most common in elderly men, and pain is more common because of bony involvement.

Metastases are characterized by a rapid onset of orbital symptoms, which include exophthalmos and globe displacement.

 

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TABLE 95-2 — AGE DISTRIBUTION OF COMMON ORBITAL DISEASES

 

Frequency (%)

Diagnostic Group

Childhood and Adolescence (0–20 years)

Middle Age (21–60 years)

Later Adult Life (61+ years)

Adenoid cystic carcinoma of lacrimal gland

18

73

9

Capillary hemangioma

100

0

0

Cavernous hemangioma

10

75

15

Cystic lesions

77

3

4

Fibrous histiocytoma

25

50

25

Infectious processes

35

3

3

Inflammatory lesions

12

5

9

Lymphangiomas

6

1

0

Lymphoproliferative diseases

1

3

12

Optic nerve glioma

5

1

1

Optic nerve meningioma

4

88

8

Pleomorphic adenoma of lacrimal gland

0

89

11

Rhabdomyosarcoma

98

2

0

Secondary and metastatic malignancies

1

2

9

Thyroid orbitopathy

4

59

40

Trauma

7

4

2

(Modified from Dutton JJ, Frazier Byrne S, Proia A. Diagnostic atlas of orbital diseases. Philadelphia: WB Saunders; 2000:1–5.)

Data rounded to the nearest percentage point.

 

 

 

 

TABLE 95-3 — TEMPORAL ONSET OF COMMON ORBITAL DISEASES

Hours

Days

Weeks

Months

Years

Traumatic

Inflammatory

Inflammatory

Neoplastic

Neoplastic

Hemorrhagic

Infectious

Neoplastic

Lymphoid

Degenerative

Infectious

Traumatic

Traumatic

Vascular

Lymphoid

 

Hemorrhagic

Lymphoid

Inflammatory

Vascular

 

Vascular

Vascular

Degenerative

Inflammatory

(Modified from Dutton JJ, Frazier Byrne S, Proia A. Diagnostic atlas of orbital diseases. Philadelphia: WB Saunders; 2000:1–5.)

 

 

 

 

TABLE 95-4 — PRIMARY ORIGINS OF METASTATIC TUMORS OF THE ORBIT

Origin

Percent

Breast

53

Prostate

11

Gastrointestinal

11

Lung

4

Sarcomas and other

21

(Modified from Dutton JJ, Frazier Byrne S, Proia A. Diagnostic atlas of orbital diseases. Philadelphia: WB Saunders; 2000:1–5.)

 

 

ORBITAL IMAGING.

Metastatic carcinomas usually are poorly defined, nonencapsulated, diffuse masses that are somewhat infiltrative. Extraocular muscles often are involved. Osteoblastic changes may be seen with prostatic carcinoma. On MRI, the T1-weighted image is usually isointense and the T2-weighted image hyperintense to muscle.

 

 

 

Causes of Abaxial Globe Displacement*

 

DOWNWARD DISPLACEMENT

Fibrous dysplasia

 

Frontal mucocele

 

Lymphoma

 

Neuroblastoma

 

Neurofibroma

 

Schwannoma

 

Subperiosteal hematoma

 

Thyroid orbitopathy

 

 

UPWARD DISPLACEMENT

Lacrimal sac tumors

 

Lymphoma

 

Maxillary sinus tumor

 

Metastatic tumors

 

 

LATERAL DISPLACEMENT

Ethmoid mucocele

 

Lacrimal sac tumors

 

Lethal midline granuloma

 

Metastatic tumors

 

Nasopharyngeal tumors

 

Rhabdomyosarcoma

 

 

MEDIAL DISPLACEMENT

Lacrimal fossa tumors

 

Sphenoid wing meningioma

 

 

* The direction of ocular displacement may be helpful in narrowing the differential diagnosis.

 

 

 

ECHOGRAPHY.

A metastatic carcinoma has an irregular shape with a surface that can be poorly to well defined. The carcinoma often is diffuse, with a medium to high internal reflectivity, but low reflectivity is seen with small cell carcinoma of the lung. Vascularity is minimal to absent.

TREATMENT AND PROGNOSIS.

Treatment requires chemotherapy combined with local radiotherapy. Orchiectomy may be indicated for prostate carcinoma, and hormonal therapy for breast carcinoma.

Orbital metastases from carcinoma reflect more widespread systemic disease, so the prognosis for survival is generally poor.

LACRIMAL GLAND LESIONS

Lesions of the lacrimal gland include infiltrative processes (such as inflammatory diseases and lymphoma), structural disorders (such as cysts), and epithelial neoplasms. [6] [7] [8] [9] [10] Epithelial tumors represent 20–25% of all lacrimal gland lesions. The appropriate management of lacrimal fossa lesions requires a thorough evaluation and determination of the cause. Almost all lacrimal gland lesions result in a mass effect, with swelling of the lateral eyelid and often with a downward and medial displacement of the globe ( Box 95-1 ). Inflammatory processes are more commonly associated with pain, eyelid edema, and conjunctival chemosis and injection.

Pleomorphic Adenoma (Benign Mixed Cell Tumor)

KEY POINTS.

Pleomorphic adenomas occur mainly in the orbital lobe and rarely in the palpebral lobe of the lacrimal gland. [11] [12] [13] [14] [15] [16] They are composed of epithelial and mesenchymal elements (thus the term benign “mixed” cell tumor), but both elements are derived from epithelium. Key features are:

• They represent 3–5% of all orbital tumors, 25% of lacrimal mass lesions, and 50% of epithelial lacrimal gland tumors.

• Most commonly they occur in the second to fifth decades of life (mean age, 39 years).

• The male-female ratio is 1.5:1.

Orbital symptoms are painless exophthalmos, axial downward displacement of the globe, diplopia, retinal striae, fullness

 

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Figure 95-1 Benign mixed tumor. A, The patient had proptosis of the left eye for quite some time. It had gradually increased in severity. B, The characteristic diphasic pattern is shown. It consists of a pale background that has a myxomatous stroma and a relatively amorphous appearance, contiguous with quite cellular areas that contain mainly epithelial cells. C, Cellular epithelial areas; M, myxomatous stroma; S, surface of tumor. (From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

of the upper eyelid, and a palpable eyelid mass. These tumors are slowly progressive over 12 or more months.

ORBITAL IMAGING.

Well-circumscribed, round to oval, encapsulated lesions are typical. Remolding of the bone may be seen with long-standing tumors, but no bone destruction occurs. The tumors may be cystic and may contain areas of calcification. On MRI the T1-weighted image is hypointense and the T2-weighted image hyperintense to muscle.

ECHOGRAPHY.

Round to oval shapes with well-defined surface spikes are seen, with medium to high reflectivity, a regular acoustic structure, and moderate sound attenuation. Cystic cavities may occur.

PATHOLOGY.

Pleomorphic adenomas are encapsulated tumors that demonstrate ducts, cords, and squamous pearls, with myxoid and chondroid tissue ( Fig. 95-1 ).

TREATMENT AND PROGNOSIS.

These adenomas must be excised completely with an intact capsule; biopsy may result in recurrence associated with infiltration. Malignant degeneration occurs at a rate of 10% in 10 years.

The prognosis is generally very good, despite the possibility of malignant transformation.

Adenoid Cystic Carcinoma

KEY POINTS.

Adenoid cystic carcinoma accounts for 23% of all epithelial tumors of the lacrimal gland and is the most common epithelial malignancy of the lacrimal gland ( Table 95-5 ). [17] Key features are:

• It occurs most commonly in the fourth decade of life but may be seen at any age.

• It is slightly more common in women.

• The duration of symptoms is generally short—often less than 6 months, and usually less than 12 months.

 

 

TABLE 95-5 — FREQUENCY OF LACRIMAL FOSSA LESIONS

Lesion

Frequency (%)

Dacryoadenitis

51

Pleomorphic adenoma

18

Reactive lymphoid hyperplasia

9

Adenoid cystic carcinoma

7

Dacryops (epithelial cyst)

5

Lymphoma

4

Mucoepidermoid carcinoma

3

Pleomorphic adenocarcinoma

2

Plasmacytoid lesions

1

(Modified from Rootman JL. Diseases of the orbit. A multidisciplinary approach. Philadelphia: JB Lippincott; 1988:119–39; and Shields JA, ed. Diagnosis and management of orbital tumors. Philadelphia: WB Saunders; 1989:291–315.)

 

 

Orbital symptoms include exophthalmos, downward globe displacement, ptosis, and diplopia. Orbital pain as a result of perineural spread of tumor is common, seen in 10–40% of cases.

ORBITAL IMAGING.

Computed tomography and MRI usually show a poorly demarcated, irregular lesion that may extend along the lateral wall to the orbital apex. Bone destruction is common, and foci of calcification are seen frequently. On MRI the T1- and T2-weighted images are hyperintense to muscle, and the signal is heterogeneous.

ECHOGRAPHY.

Adenoid cystic carcinoma usually appears as a diffuse, infiltrative lesion with indistinct borders (although it may be well defined), with medium to high internal reflectivity and an irregular internal structure. Sound attenuation is moderate to strong.

PATHOLOGY.

Solid cords of malignant epithelial cells are seen, with cystic spaces (“Swiss cheese” appearance) or hyalinization of cylinders of connective tissue ( Fig. 95-2 ).

TREATMENT AND PROGNOSIS.

Treatment consists of radical en bloc excision or exenteration, with wide margins including bone. Adjunctive radiotherapy for incompletely excised lesions may be necessary. The prognosis is dismal, with relentless recurrences. The mortality rate is high.

MESENCHYMAL TUMORS

Nonosseous mesenchymal tumors arise from fibroblasts, myoblasts, and lipoblasts. Classification of such lesions is difficult, as their features overlap, so the terminology is confusing. Together, these orbital lesions form an important group that accounts for about 8% of all orbital lesions. [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31]

Fibrous Histiocytoma

KEY POINTS.

Fibrous histiocytoma is a benign or malignant mesenchymal tumor that arises from fascia, muscle, or other soft tissues.[32] [33] In children, it may result from early orbital radiotherapy. In adults, it is the most common mesenchymal orbital tumor, usually seen in middle-aged patients (40–60 years).

The upper nasal quadrant is the most common orbital site. Symptoms are exophthalmos, decreased vision, diplopia, ptosis, motility restriction, and epiphora. The lesions may be circumscribed or infiltrative and can be locally aggressive.

ORBITAL IMAGING.

Usually a well-defined, rounded mass is seen, as in other benign lesions, but the tumor may be more infiltrative. On MRI the signal is heterogeneous, with isointense T1 and variable T2 signals with respect to muscle. Enhancement with gadolinium is moderate.

 

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ECHOGRAPHY.

The lesion is well outlined, with a regular internal structure of low to medium reflectivity and moderate sound attenuation. Vascularity is variable.

PATHOLOGY.

The tumor is a mixture of spindle-shaped fibroblasts and histiocytes arranged in a storiform pattern, twisted about a central focus ( Fig. 95-3 ). The benign form (63% incidence) is a well-circumscribed, slow-growing lesion with a fine capsule. A small potential exists for malignant degeneration.

 

 

 

 

Figure 95-2 Adenoid cystic carcinoma. A, The patient had a rapidly progressing proptosis of the left eye. B, The characteristic “Swiss cheese” pattern (S) of adenoid cystic carcinoma is shown. The “Swiss cheese” tumor is also present in the perineural sheath around the ciliary nerve (C). Adenoid cystic carcinoma is noted for its rapid invasion of ciliary nerves. (From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

 

 

 

 

Figure 95-3 Fibrous histiocytoma. A, This is the fourth recurrence of an orbital tumor that was first excised 10 years previously. The histology of the primary lesion and of the four recurrences appear identical. B, A histological section shows the diphasic pattern consisting of a histiocytic component (H), mainly on the far left, and a fibrous component (F). (Case reported by Jones WD III, Yanoff M, Katowitz JA. Recurrent facial fibrous histiocytoma. Br J Plast Surg. 1979; 32:46–51.)

The malignant form (37% incidence) is more infiltrative and rapidly growing; it is often associated with pain and necrosis.

TREATMENT AND PROGNOSIS.

Local surgical excision or orbital exenteration is required, with recurrences being common (in up to 30% of cases). Radiotherapy offers no benefit, and the effects of chemotherapy are unknown.

For the benign form, the prognosis for life is excellent. With malignant tumors, the overall mortality rate is more than 40%.

Rhabdomyosarcoma

KEY POINTS.

Rhabdomyosarcoma is the most common soft tissue mesenchymal tumor in children, accounting for 3.4% of all childhood malignancies. [34] [35] [36] [37] The tumors arise from pluripotential mesenchymal precursors that normally differentiate into striated muscle cells. About 70% occur during the first decade of life (mean age, 7–8 years; range, 0–78 years), and boys are affected more commonly than girls, at a ratio of 5:3. In the orbit, the most common histological variant is the embryonal type, followed by the alveolar type.

Symptoms may be acute to subacute, with rapidly progressive exophthalmos, eyelid edema, and ptosis. This rapidity may cause diagnostic confusion with an infectious process. The tumor is located in the retrobulbar muscle cone in 50% of cases, and in the superior orbit in 25% of cases.

ORBITAL IMAGING.

Typically, the tumor presents as an irregular but well-defined soft tissue mass ( Fig. 95-4 ). Bony erosion may be seen but is uncommon. On MRI the T1 signal is isointense

 

 

Figure 95-4 Rhabdomyosarcoma of the lateral orbital wall in a 7-year-old girl.

 

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to hyperintense, and the T2 signal is hyperintense with respect to muscle.

ECHOCARDIOGRAPHY.

The lesion has variable borders (but they are usually well circumscribed; occasionally there are bony defects), low to medium reflectivity, moderate sound attenuation, and a somewhat irregular structure. Vascularity is variable.

PATHOLOGY.

Cross-striations may be seen in 50–60% of embryonal-type tumors and in 30% of the alveolar type ( Fig. 95-5 ). Myoglobulin is a specific immunohistochemical marker. Electron microscopy shows actin myofilaments and myosin filaments.

DIFFERENTIAL DIAGNOSIS.

The differential diagnosis includes inflammatory processes, orbital cellulitis, metastatic

 

 

 

 

 

 

Figure 95-5 Embryonal rhabdomyosarcoma. A, The patient has a unilateral right ocular proptosis of very recent onset. Often, rhabdomyosarcoma presents rapidly, causes lid redness, and is mistaken for orbital inflammation. B, A marked embryonic cellular pattern is shown, hence the term embryonal rhabdomyosarcoma (A, relatively acellular area; B, blood vessels; C, relatively cellular area). C, A trichrome stain shows characteristic cross-striations in the cytoplasm of some of the rhabdomyoblasts. Cross-striations (C), although not abundant in embryonal rhabdomyosarcoma, can be seen in sections stained with hematoxylin and eosin but are easier to see with special stains. (A–C, From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

neuroblastoma, chloroma, lymphangioma, and ruptured dermoid cyst.

STAGING.

There are four stages:

 

I.

Localized tumor, completely resected

 

II.

Regional spread, positive nodes, grossly resected

 

III.

Gross residual tumor remaining after incomplete resection

 

IV.

Distant metastases

TREATMENT AND DIAGNOSIS.

An immediate biopsy is required to confirm the diagnosis. Surgical excision is carried out only if the lesion is well circumscribed. The excision can be performed easily without excessive tissue damage. Local radiotherapy doses are 4000?cGy for stage II and 5000?cGy for stages III and IV. Adjuvant chemotherapy is given, using vincristine, actinomycin D, and cyclophosphamide. (Some centers prefer only surgery and chemotherapy, to avoid the potential for radiation-induced orbital malignancies in children.)

The 5-year survival rate is 95%; there is a more favorable prognosis for orbital tumors because of the near absence of orbital lymphatics. For local treatment failures, orbital exenteration may be necessary.

NEUROGENIC TUMORS

Peripheral nerves in the orbit are subject to tumors that arise from various cellular components such as Schwann cells, axons, endoneural fibroblasts, and nerve sheaths ( Table 95-6 ). In contrast, the optic nerve, which represents a white-matter tract of the central nervous system (CNS), may give rise to CNS tumors such as astrocytomas and meningiomas.

Plexiform Neurofibroma

KEY POINTS.

Plexiform neurofibroma is the most common benign peripheral nerve tumor in the eyelid and orbit and is considered characteristic of neurofibromatosis type 1. [38] [39] [40] [41] The tumor grows along the nerve, is invasive, and is not encapsulated. Key features are:

• A propensity for sensory nerves, but also may involve motor, parasympathetic, and sympathetic nerves.

• Children in the first decade of life are affected most commonly.

• 31% of plexiform neurofibromas occur in the eyelids.

Clinically, this tumor has been described as a palpable “bag of worms,” with thickened overlying skin and an S-shaped eyelid ( Fig. 95-6 ).

It may be associated with uveal neurofibromas (50%), iris (Lisch) nodules (77%), prominent corneal nerves (25%), optic nerve gliomas (15%), and pulsatile proptosis from an absence of the greater sphenoid wing.

ORBITAL IMAGING.

A diffuse, irregular mass is seen with variable contrast enhancement. It may involve extraocular muscles, orbital fat, and the cavernous sinus. On MRI the T1 is hypointense and the T2 hyperintense to muscle.

 

 

TABLE 95-6 — FREQUENCY OF THE MOST COMMON NEUROGENIC ORBITAL LESIONS

Lesion

Frequency (%)

Sphenoid wing meningioma

30

Optic nerve glioma

22

Neurofibroma

19

Schwannoma

14

Optic sheath meningioma

11

Other

4

(Data from Rootman JL. Diseases of the orbit. A multidisciplinary approach. Philadelphia: JB Lippincott; 1988:119–39; Shields JA, ed. Diagnosis and management of orbital tumors. Philadelphia: WB Saunders; 1989:291–315; and the author’s personal data.)

 

 

 

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Figure 95-6 Plexiform neurofibroma of the right eyelid in a child with neurofibromatosis.

 

 

Figure 95-7 Plexiform neurofibroma. Diffuse proliferation of Schwann cells within the nerve sheath enlarges the nerve. N, Thickened abnormal nerves. (From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

ECHOCARDIOGRAPHY.

The lesion has a poorly outlined, irregular contour, with high internal reflectivity, minimal attenuation, and an irregular internal structure.

PATHOLOGY.

Interwoven bundles of axons, Schwann cells, and endoneural fibroblasts are seen in a mucoid matrix ( Fig. 95-7 ). A characteristic cellular perineural sheath defines the tumor cords. Immunohistochemistry is positive for S100 stain.

TREATMENT AND PROGNOSIS.

Surgical excision is generally difficult and frustrating, with excessive bleeding and a poor cosmetic result. Repeated debulking may be necessary for severe symptoms, and orbital exenteration for extensive cases. Radiotherapy offers no benefit.

There is a small risk of malignant transformation. These tumors may occasionally erode into the anterior cranial fossa, which results in death.

Schwannoma (Neurilemmoma)

KEY POINTS.

Schwannoma is a Schwann cell tumor that arises as an outpouching from peripheral or cranial nerves (e.g., acoustic neuroma); it has a neural crest origin.[42] [43] Schwannomas represent 1% of all orbital tumors and 35% of peripheral nerve tumors; they are mostly benign but rarely may undergo malignant transformation in patients with neurofibromatosis.

Schwannoma is seen most commonly in young adults to middle-aged individuals (20–50 years). It presents as a slow-growing, painless, well-defined solitary mass, usually in the superior orbit, and is frequently cystic. Orbital symptoms may include exophthalmos, diplopia, and visual loss from optic nerve compression.

ORBITAL IMAGING.

The tumor is typically an extraconal, fusiform, well-defined, sometimes cystic mass that is aligned anteroposteriorly along the involved nerve. On MRI the signal is homogeneous to heterogeneous; T1 is hypointense and T2 isointense to muscle.

 

 

 

 

Figure 95-8 Neurilemmoma. A, Proptosis of the patient’s left eye had been present for many months and was increasing in size. An orbital tumor was removed. B, Ribbons of spindle Schwann cell nuclei can be seen. This shows a tendency toward palisading. Areas of relative acellularity, mimicking tactile corpuscles, are called Verocay bodies. This pattern is called the Antoni type A pattern. (A–B, From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

ECHOGRAPHY.

The lesion has well-defined surface spikes, low to medium internal reflectivity, and a regular acoustic structure. Cystic cavities may be present, and moderate sound attenuation may occur.

PATHOLOGY.

The encapsulated mass has yellow areas and patterns of cells described as Antoni A (whorls) or Antoni B (no palisading) patterns ( Fig. 95-8 ). Spindle cells are seen with vesiculated nuclei in a palisading configuration. The cells are negative for alcian blue and positive for S100 stain.

TREATMENT AND PROGNOSIS.

Surgical excision is required. The prognosis for life is good, except following intracranial spread. Late orbital recurrences may be seen after partial excision.

Malignant Peripheral Nerve Sheath Tumor (Malignant Schwannoma)

KEY POINTS.

Malignant peripheral nerve sheath tumors are rare malignant tumors of Schwann cells and perineural cells that arise de novo or in association with neurofibromatosis.[44] [45] When associated with neurofibromatosis, the onset is slow, characterized by exophthalmos, globe displacement, and occasionally pain, ptosis, visual loss, diplopia, and chemosis. The tumors generally occur in patients 20–50 years of age, or earlier in neurofibromatosis.

The clinical course is characterized by relentless invasion along tissue planes to the middle cranial fossa. Metastases to the lungs are common.

ORBITAL IMAGING.

A poorly defined, irregular mass is seen. Bone destruction may occur when the lesion is large.

ECHOGRAPHY.

The lesion appears as an irregular mass with low internal reflectivity.

 

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PATHOLOGY.

The tumor has plexiform, swollen nerve bundles and spindle-shaped cells in whorls of interlacing fascicles.

TREATMENT AND PROGNOSIS.

Wide surgical resection is required. Ancillary chemotherapy and radiotherapy may be palliative only. Prognosis is very poor, with death from metastases or intracranial spread.

Neuroblastoma

KEY POINTS.

Neuroblastoma is an undifferentiated malignant tumor of primitive neuroblasts, which may be metastatic to the orbit.[46] [47] It represents the second most common orbital tumor in children, after rhabdomyosarcoma. It arises from the sympathetic system and ganglia and represents the peripheral nervous system counterpart of retinoblastoma. Rarely, neuroblastomas may represent primary lesions in the orbit, where they may arise from the ciliary ganglion. Key features are:

• 60% of the primary tumors occur in the abdomen.

• 10–40% of systemic neuroblastomas result in orbital metastases, on average 3 months after diagnosis.

• 90% of orbital lesions originate from the abdomen.

• Only 8% of cases first present with an orbital lesion; in 92% of cases the presence of an extraorbital primary tumor is already known.

• 40% of orbital lesions are bilateral.

• The mean age at presentation is 2 years old.

• 75% of cases occur before the age of 4 years.

Symptoms include rapid progression of exophthalmos over several weeks, lid ecchymosis from necrosis and hemorrhage, eyelid edema, ptosis, Horner’s syndrome (from mediastinal tumors), papilledema, retinal striae, and decreased vision. Systemic symptoms may involve fever, weakness, and an abdominal or thoracic mass.

ORBITAL IMAGING.

An irregular, poorly circumscribed mass is seen, frequently associated with bone destruction and separation of sutures, especially at the zygoma. Metastases to the skull bones occur in 74% of cases.

PATHOLOGY.

The lesion is a soft, friable, bluish mass; small round cells that resemble lymphocytes with specks of calcium and areas of necrosis are seen. Electron microscopy reveals neurosecretory tubules.

TREATMENT AND PROGNOSIS.

If no systemic primary disease exists, the orbital tumor can be excised. With systemic primary disease, chemotherapy yields resolution in 60–70% of cases in 4–6 months. Radiotherapy (1500?cGy in children and 4000?cGy in patients older than 10 years old) may be used for local orbital disease.

Recurrences may be seen in 90% of cases over 1–2 years, and a 50–60% mortality rate occurs after 2 years. Bony and orbital metastases are associated with a poorer prognosis.

Optic Nerve Glioma (Pilocytic Astrocytoma of Childhood)

KEY POINTS.

Optic nerve glioma is a neoplasm of astrocytes[48] that affects primarily children (mean age, 8 years). No sex predilection exists. The optic nerve alone is affected in 28% of cases; 72% involve the optic chiasm, and of these, 43% involve the chiasm and midbrain. In neurofibromatosis, the lesion may be bilateral. In 29% there is an association with type 1 neurofibromatosis.

Symptoms include slow loss of vision, optic atrophy or edema, and exophthalmos. After an initial decrease, vision remains stable in 80% of patients. Hypothalamic signs may be seen in 22% of cases. Rapid enlargement of the lesion occurs from mucoid degeneration and arachnoid hyperplasia.

ORBITAL IMAGING.

Typically, the lesion appears as an intraconal, fusiform enlargement of the optic nerve, with or without a chiasmal mass. The nerve may appear kinked with cystic spaces. On MRI the T1 signal is hypotense to isointense, and the T2 signal shows variable intensity compared to muscle ( Fig. 95-9 ). Enhancement with gadolinium is variable.

 

 

Figure 95-9 Optic nerve glioma in a child with neurofibromatosis type 1.

 

 

Figure 95-10 Optic nerve “glioma.” Well-differentiated astrocytes spread out the pial septa (P). (From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

ECHOGRAPHY.

Echography demonstrates a smooth, fusiform enlargement of the optic nerve with low to medium and regular internal reflectivity. The 30° test for increased subarachnoid fluid is usually negative.

PATHOLOGY.

Juvenile pilocytic astrocytomas demonstrate cystic spaces that contain a mucoid material and pial septae that are separated by well-differentiated astrocytes ( Fig. 95-10 ). Eosinophilic Rosenthal fibers may represent degenerated astrocytic processes. Immunohistochemistry is positive for neuron-specific enolase.

TREATMENT AND PROGNOSIS.

Treatment consists of observation if the vision is good. The patient should be followed with serial MRI scans. Surgical excision is offered if a tumor approaches the chiasm. Surgery also is indicated for pain or disfiguring proptosis. The role of radiotherapy remains controversial; it may be associated with CNS complications. More recently, chemotherapy has shown promising results.[49]

Prognosis for vision is poor. For lesions confined initially to the optic nerve, prognosis for life is good, with a mortality of 10%. For those lesions that involve the chiasm, mortality approaches 20%. Once the midbrain and hypothalamus are involved, the overall prognosis is poor, with mortality exceeding 55%.

Optic Nerve Sheath Meningioma

KEY POINTS.

Optic nerve sheath meningioma is a benign neoplasm of meningothelial cells of arachnoid tissue[50] that affects primarily middle-aged adults (20–60 years). Women are involved slightly more commonly than men, at a ratio of 3:2. In 4–9% of cases there is an association with type 1 neurofibromatosis,

 

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and in 6% of cases the lesion may be bilateral; 5% of meningiomas are confined to the optic canal, which makes diagnosis difficult.

Symptoms and signs include slowly progressive exophthalmos over several years, visual loss, optic disc edema, optic atrophy, development of opticociliary shunt vessels, and ocular motility restriction.

ORBITAL IMAGING.

The lesion usually is seen as a tubular enlargement of the optic nerve with a characteristic “tram-track” pattern of an enhancing nerve sheath with a lucent central nerve. Small areas of calcification may be seen. Marked contrast enhancement on computed tomography is characteristic. On MRI the T1 signal is hypointense, and the T2 signal is hyperintense. Heterogeneity results from low signal areas that represent calcium. Areas of subarachnoid fluid distention are hyperintense.

ECHOGRAPHY.

Enlargement of the optic nerve is seen, with medium to high internal reflectivity, and calcification may be apparent. The 30° test may be positive anterior to the tumor, indicating increased subarachnoid fluid.

PATHOLOGY.

There are several histological types. The meningothelial type of lesion shows syncytial lobules of meningothelial cells. The psammous type demonstrates calcified concretions or psammoma bodies ( Box 95-2 ). A rare angioblastic type contains vascular elements that resemble a hemangiopericytoma.

TREATMENT AND PROGNOSIS.

Treatment consists of observation if the vision remains good. In patients with blindness and significant proptosis, or when the optic canal is threatened, surgical excision is indicated. The role of radiotherapy remains controversial, but it may slow progression.

The prognosis for life is excellent, but visual outcome typically is poor.

LYMPHOPROLIFERATIVE DISEASES

Lymphoid lesions are uncommon in the orbit and account for 6% of all orbital mass lesions ( Table 95-7 ). This group includes lymphocytic, plasmacytic, and leukemic lesions. Among the

 

 

Calcified Orbital Lesions

Phlebolith

 

Orbital varix

 

Lymphangioma

 

Thrombosed atrioventricular shunt

 

Chronic inflammation

 

Malignant lacrimal gland tumors

 

Optic nerve sheath meningioma

 

Dermoid cyst

 

Mucocele walls

 

Fibro-osseous tumors

 

 

 

 

 

 

TABLE 95-7 — FREQUENCY OF LYMPHOPROLIFERATIVE DISEASES OF THE ORBIT

Disease

Frequency (%)

Lymphoma

51

Reactive and atypical lymphoid hyperplasia

36

Plasma cell dyscrasias

7

Leukemia

2

Histiocytoses

4

(Modified from Dutton JJ, Frazier Byrne S, Proia A. Diagnostic atlas of orbital diseases. Philadelphia: WB Saunders; 2000:1–5.)

 

 

lymphoid infiltrates, lesions are divided into three categories: idiopathic inflammations (pseudotumors), lymphoproliferative reactive and atypical diseases, and lymphomas. The relationships between the last two groups and their relationship to systemic disease are not always clear, and some confusion still surrounds the diagnosis and prognosis of each.

Benign Reactive Lymphoid Hyperplasia

KEY POINTS.

This disease constitutes a benign proliferation of lymphoid follicles that contain polymorphic lymphocytes that are immunohistochemically polyclonal.[51] [52] Benign reactive lymphoid hyperplasia (BRLH) occurs most commonly in the anterior superior orbit, with a predilection for the lacrimal gland (15%). The clinical course is indolent, with painless exophthalmos, globe displacement, and typically normal vision. A firm, rubbery mass is often palpable beneath the orbital rim, and there may be a pink subconjunctival “salmon-patch” infiltrate.

ORBITAL IMAGING.

An infiltrative mass is seen in the eyelids or anterior orbit. It typically molds to the globe and other adjacent structures and may extend along the rectus muscles. On MRI the T1 signal is hypointense and the T2 signal hyperintense to muscle.

 

 

 

 

Figure 95-11 Reactive lymphoid hyperplasia. A, The patient noted a fullness of the lower right lid. Large, thickened, redundant folds of conjunctiva in the inferior cul-de-sac are seen. The characteristic “fish flesh” appearance of the lesion suggests the clinical differential diagnosis of a lymphoid or leukemic infiltrate or amyloidosis. B, Lymphocytes are mature, quite small, and uniform; occasional plasma cells are large monocytoid lymphocytes. The uniformity of the lymphocytes makes it difficult to differentiate this benign lesion from a well-differentiated lymphosarcoma. The very mature appearance of the cells and the absence of atypical cells, along with the presence of plasma cells, suggests the diagnosis of a benign lesion. In such cases, testing using monoclonal antibodies may be quite helpful. If the population is of mixed B and T cells, the chances are that the tumor is benign. If it is predominantly of one cell type or the other, usually B cells, it is probably malignant and may represent mucosal-associated lymphoid tissue of the conjunctiva. (A–B, From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

 

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ECHOGRAPHY.

The lesion has a variable shape and borders. A-scan shows a regular acoustic structure with low to medium reflectivity.

PATHOLOGY.

Typically, the tumor is a polymorphous array of small lymphocytes and plasma cells, with mitotically active germinal centers ( Fig. 95-11 ). Immunohistochemistry is positive for polyclonal T- and B-cell markers.

TREATMENT AND PROGNOSIS.

Treatment involves systemic corticosteroids or local radiotherapy at 1500–2000?cGy. Some lesions may require cytotoxic agents (chlorambucil) for control. There is a 15–25% chance of developing systemic lymphoma within 5 years.

Atypical Lymphoid Hyperplasia

KEY POINTS.

Atypical lymphoid hyperplasia (ALH) represents an intermediate between BRLH and malignant lymphoma and may be unilateral or bilateral.[53] Presentation is as for BRLH, but ALH may involve other systemic organs and more frequently does not respond to corticosteroids. There is a 15% incidence of extraorbital involvement, and systemic lymphoma may develop.

ORBITAL IMAGING AND ECHOGRAPHY.

Computed tomography and MRI scans are similar to those for BRLH.

PATHOLOGY.

Monomorphous sheets of lymphocytes that have larger nuclei than those of BRLH are seen. Some abortive follicles may be present.

TREATMENT AND PROGNOSIS.

If no systemic involvement exists, radiotherapy at 2500–3000?cGy is appropriate. There is a 40% chance of systemic lymphoma developing within 5 years.

 

 

Figure 95-12 Subconjunctival anterior orbital lymphoma.

 

 

Figure 95-13 Lymphoma infiltrating along the lateral orbital wall.

Malignant Orbital Lymphoma (Lymphosarcoma)

KEY POINTS.

Malignant orbital lymphoma is a low-grade malignancy characterized by a proliferation of monoclonal B cells (non-Hodgkin’s), which arise in lymph nodes or in an extranodal site such as the orbit.[54] [55] Most commonly affected is the older age group (50–70 years). Clinically, a palpable mass may be present in the anterior orbit. Symptoms include exophthalmos, occasional diplopia, lid edema, and ptosis ( Fig. 95-12 ).

In 75% of cases the process is unilateral, and in 25% it is bilateral; 40% of cases are associated with systemic disease at the time of diagnosis.

ORBITAL IMAGING.

A well-defined mass is seen that molds to encompass adjacent structures. Most lesions are located in the anterior, superior, and lateral orbit and frequently involve the lacrimal gland ( Fig. 95-13 ).

ECHOGRAPHY.

The lesion has a variable shape and borders, with a regular acoustic structure and low to medium reflectivity.

PATHOLOGY.

Infiltrative, anaplastic lymphocytes with large cleaved nuclei and frequent nucleoli are seen. Follicles are absent. Immunohistochemistry reveals a monoclonal proliferation of B cells.

TREATMENT AND PROGNOSIS.

If no systemic involvement occurs, observation is warranted for low-grade differentiated lesions. For less well-differentiated types, chemotherapy or radiotherapy at 2500–3000?cGy is recommended.

When the disease is confined to the orbit, the visual prognosis is excellent, but the overall prognosis for life is variable. A 60% chance exists of developing systemic lymphoma within 5 years.

HISTIOCYTIC TUMORS

Histiocytic tumors are rare proliferative disorders of histiocytes that range from solitary benign lesions to those that exhibit a more malignant course. A typical feature of all these lesions is the presence of Langerhans’ cells, a type of histiocyte normally found in the epidermis.

Eosinophilic Granuloma (Histiocytosis X)

KEY POINTS.

Eosinophilic granuloma is the most common and benign form of the histiocytosis X group.[56] The disease affects primarily children and teenagers (from birth to 20 years of age). It consists of a unifocal, granulomatous proliferation in the bone. Orbital involvement occurs in up to 20% of cases, most commonly in the superotemporal orbit.

Clinically, a rapid onset of abaxial displacement of the globe occurs, and painful superolateral swelling. Erythema and inflammatory signs are seen in the overlying skin.

ORBITAL IMAGING.

Typically, an osteolytic lesion is seen near the superotemporal bony rim. Usually an irregular contour is noted, with marginal hyperostosis. Occasionally, the lesion may extend into the cranial fossa.

ECHOGRAPHY.

A well-circumscribed mass with low internal reflectivity occurs in the superotemporal orbit. It typically is associated with a bony defect.

PATHOLOGY.

This is a soft, friable, tan–yellow tumor with sheets of binuclear histiocytes, eosinophils, and giant cells ( Fig. 95-14 ). Characteristic Langerhans’ granules are seen in the cytoplasm.

TREATMENT AND PROGNOSIS.

Surgical curettage generally is curative, but radiotherapy at 900–1500?cGy also may be used. The prognosis is very good.

INFLAMMATIONS AND INFECTIONS

Inflammatory diseases are common orbital lesions that may simulate neoplasms. They include a variety of acute and subacute idiopathic processes, chronic inflammations, and specific inflammations of uncertain etiology. Most notable among these

 

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Figure 95-14 Eosinophilic granuloma. A, A 4-year-old boy presented clinically with rapid onset of erythema and swelling over the lateral edge of the left orbit. Osteomyelitis versus rhabdomyosarcoma was diagnosed clinically; the area was explored surgically. B, Histological section shows large histiocytes (abnormal Langerhans’ cells) and numerous eosinophils characteristic of a solitary eosinophilic granuloma. (A, Courtesy of Dr. D.B. Schaffer. In: Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002. B, From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

lesions is Graves’ orbitopathy, which accounts for more than half of all such cases.

Diffuse Idiopathic Orbital Inflammation (Pseudotumor)

KEY POINTS.

Diffuse orbital pseudotumor is a nongranulomatous acute to subacute inflammatory disease with no systemic manifestations that may affect teenagers to the elderly.[57] Most commonly it occurs in the anterior or mid orbit, and it frequently involves the lacrimal gland. It is typically unilateral but rarely may be bilateral. Uveitis and retinal detachment may be associated with scleritis.

Symptoms include abrupt pain, conjunctival injection, chemosis, lid edema, exophthalmos, and motility restriction. A palpable mass is detected in 50% of cases.

ORBITAL IMAGING.

Posterior Tenon’s capsule shows thickening and enhancement. A shaggy orbital infiltrate or discrete mass is present, which may mold to the globe or optic nerve sheath. The lacrimal gland may be enlarged. On MRI the T1 signal is hypointense and the T2 signal is hyperintense to muscle. Moderate enhancement occurs with gadolinium.

ECHOGRAPHY.

The lesion has a variable shape and borders, with low to medium reflectivity, a regular acoustic structure, and weak sound attenuation. Edema in Tenon’s capsule may appear as an area of lucency behind the globe.

PATHOLOGY.

The pseudotumor is a gray rubbery mass composed of a polymorphic infiltrate of lymphocytes, eosinophils, plasma cells, and polymorphonuclear leukocytes. In the sclerosing type, the dominant feature is scarification and collagen deposition.

TREATMENT AND PROGNOSIS.

Systemic corticosteroids typically result in a dramatic improvement. Rarely, some lesions may require cytotoxic agents. The sclerosing type shows little or no response to treatment.

Prognosis generally is excellent, with complete resolution of disease.

Myositis

KEY POINTS.

An acute to subacute idiopathic inflammation of the extraocular muscles, myositis may affect teenagers to the elderly.[58] Typically, the disease is unilateral and involves only one muscle, most commonly the superior or lateral rectus.

Symptoms include pain, motility restriction, exophthalmos, and displacement of the globe.

ORBITAL IMAGING.

Enlargement of an extraocular muscle is seen, with involvement of the entire muscle from origin to insertion.

ECHOGRAPHY.

Echography shows a thickened muscle with low internal reflectivity and a regular acoustic structure.

TREATMENT AND PROGNOSIS.

Systemic corticosteroids generally result in prompt resolution. The prognosis is excellent.

Thyroid Orbitopathy (Graves’ Disease)

KEY POINTS.

Thyroid orbitopathy is an immunological disorder that affects the orbital muscles and fat.[59] Hyperthyroidism is seen with orbitopathy at some point in most patients, although the two are commonly asynchronous. Key features are:

• Middle-aged adults (30–50 years) are affected most frequently.

• The disease is seen in women more commonly than in men, in a ratio of 3–4:1.

• It is always a bilateral process but is often asymmetrical.

• Multiple muscles are involved simultaneously, most commonly the inferior and medial rectus.

Symptoms and signs include dry eyes, conjunctival injection, lid retraction, exophthalmos, diplopia, corneal exposure, and rarely optic nerve compression. Graves’ disease usually runs a progressive course for 3–5 years and then stabilizes.

ORBITAL IMAGING.

Increased fat lucency is seen, as well as extraocular muscle enlargement confined to the bellies, but with sparing of the insertions and origins. On MRI the T1 is isointense and the T2 isointense to slightly hyperintense to muscle.

ECHOGRAPHY.

Thickened muscles with medium to high internal reflectivity and an irregular acoustic structure are seen on echography.

PATHOLOGY.

The enlarged, rubbery muscles show variable amounts of edema and infiltration with inflammatory round cells ( Fig. 95-15 ). An increased amount of acid mucopolysaccharides infiltrates the orbital tissue.

TREATMENT AND PROGNOSIS.

Symptomatic therapy is given until the disease stabilizes. Systemic corticosteroids or radiotherapy may be indicated for acute orbital inflammation and congestion.

The orbital disease is usually progressive over 1–5 years, followed by stabilization. Eyelid recession, strabismus surgery, or orbital decompression may be offered after stabilization, as needed, to improve function and cosmesis.

Orbital Cellulitis

KEY POINTS.

The major causes of orbital cellulitis are sinusitis (58%), lid or face infection (28%), foreign body (11%), and hematogenous (4%). [60] Staphylococcus and Streptococcus are the most common causative organisms in adults, Haemophilus influenzae

 

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Figure 95-15 Graves’ disease. A, In Graves’ disease, exophthalmos often looks more pronounced than it actually is because of the extreme lid retraction that may occur. This patient, for instance, had minimal proptosis of the left eye but marked lid retraction. B, The orbital contents obtained post mortem from a patient with Graves’ disease. Note the enormously thickened extraocular muscle. C, Both fluid and inflammatory cells separating the muscle bundle may be seen. The inflammatory cells are predominantly lymphocytes, plus plasma cells. (A, Courtesy Dr. HG Scheie. In: Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002. B–C, Courtesy Dr. RC Eagle Jr. In: Hufnagle TJ, et al. Opthalmology. 1984; 91:1411.)

in children. Less common organisms are Pseudomonas and Escherichia coli.

Orbital symptoms are pain, lid edema and erythema, chemosis, and axial proptosis if diffuse disease occurs or abaxial displacement if an abscess forms. Decreased ocular motility is common, and intraocular pressure may be elevated. A rapid loss of vision from optic nerve compression, optic neuritis, or vasculitis may ensue. With posterior extension, cavernous sinus thrombosis, subdural empyema, and intracranial abscess may develop.

 

 

 

Common Cystic Lesions of the Orbit

Dermoid cysts

 

Conjunctival cysts

 

Sweat gland cysts

 

Microphthalmos with cyst

 

Lacrimal gland cysts

 

Lymphangioma

 

Schwannoma

 

Infectious abscesses

 

 

 

 

Systemic symptoms may include malaise and fever. If the cavernous sinus is involved, headache, nausea, vomiting, and decreased consciousness may supervene.

The warning signs of orbital cellulitis are a dilated pupil, marked ophthalmoplegia, loss of vision, afferent pupillary defect, papilledema, perivasculitis, and violaceous lids.

ORBITAL IMAGING.

Diffuse orbital infiltrate is seen, often with opacification of adjacent sinuses.

TREATMENT AND PROGNOSIS.

In children, treatment is with systemic antibiotics; sinus drainage is needed in only 50% of cases. In adults, the drainage of sinuses and abscesses may be needed in 90% of cases.

The prognosis is very good with prompt antibiotic therapy and surgical drainage when indicated.

Wegener’s Granulomatosis

KEY POINTS.

Wegener’s granulomatosis is a necrotizing granulomatosis of the upper respiratory tract, characterized by vasculitic pneumonitis, glomerulonephritis, sinusitis, and mucosal ulcerations of the nasopharynx.[61] A limited form does not involve the kidney. The cause is T-cell immune complex formation secondary to inhaled antigens. Key features are:

• Peak incidence is in adults 40–50 years of age.

• Men are more commonly affected than women, in a ratio of 2:1.

• Classic antineutrophil cytoplasmic antibody is positive in 80% of cases.

• 40–50% of patients may have ocular involvement (mostly contiguous from the sinus or pharynx, but it may be isolated).

• 18–22% of patients demonstrate orbital involvement, usually bilateral.

Symptoms are chemosis, exophthalmos, motility restriction, papilledema, and decreased vision. Ocular tissue involvement may include scleritis and episcleritis (20–38%), uveitis (10–20%), peripheral corneal guttering (14–28%), and retinal vasculitis (7–18%).

ORBITAL IMAGING.

A diffuse orbital mass may be bilateral and may involve the adjacent nasopharynx.

PATHOLOGY.

The pathology is necrotizing granulomatous vasculitis with giant cells.

TREATMENT AND PROGNOSIS.

Treatment consists of administration of systemic corticosteroids plus cyclophosphamide or azathioprine. Radiotherapy is of doubtful value. Improvement with systemic therapy is usual, with up to 90% remission.

Patients who have the more limited form of the disease have a better prognosis.

STRUCTURAL LESIONS

Structural lesions of the orbit include choristomatous lesions such as dermoid cysts, which arise from errors in embryogenesis, and anatomical abnormalities such as mucoceles, which result from local disease processes ( Box 95-3 ).

 

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Dermoid Cyst

KEY POINTS.

A dermoid cyst is a developmental choristoma, lined with epithelium and filled with keratinized material.[62] The majority of such cysts are located in the eyelids and orbit ( Fig. 95-16 ). These cysts represent 24% of all orbital and lid masses, 6–8% of deep orbital masses, and 80% of cystic orbital lesions. Dermoid cysts may lie latent for many years before growth and may be located superficially in the eyelid and anterior orbit or deep in the orbit.

SUPERFICIAL LESIONS.

Superficial lesions arise from a sequestration of epithelium during embryogenesis along bony suture lines. They are present in early infancy, typically in the superotemporal or superonasal quadrants. Clinically, they present as a slowly enlarging, unilateral, painless, firm mass; they may be mobile or fixed to underlying structures and are free from overlying skin.

ORBITAL IMAGING.

The round, well-defined lesions have an enhancing rim that may contain calcium, and a lucent center. They may be associated with a well-corticated bone defect.

ECHOGRAPHY.

The lesion is well defined, with medium to high internal reflectivity and a somewhat irregular acoustic structure; it usually shows some compressibility.

PATHOLOGY.

The cyst usually has a thin, fibrous capsule and a central lumen lined with keratinized stratified squamous epithelium. If derived from conjunctiva, the lining may be cuboidal with goblet cells. The cyst wall contains hair follicles and sweat and sebaceous glands. The cyst contains keratin debris, hair shafts, and oily material. About 38% of cysts are associated with chronic granulomatous inflammation.

TREATMENT AND PROGNOSIS.

Complete surgical excision in one piece is required. The prognosis is excellent, but recurrences with infiltration may follow incomplete excision or rupture of the capsule.

DEEP LESIONS.

Deep lesions are seen in both children and adults. They are associated with any bony suture in the orbit and may extend across bones into the frontal sinus, temporal fossa, or cranium.

Symptoms from the slow-growing mass include proptosis, occasionally motility restriction, and decreased vision. Spontaneous rupture produces marked orbital inflammation.

ORBITAL IMAGING.

The well-defined lesion has an enhancing rim that may contain areas of calcification. The central lumen is nonenhancing and of variable density, depending on its contents; it may show a fluid-fat interface. A bone defect may be seen.

ECHOGRAPHY.

A cystic mass with low to absent internal reflectivity is seen, but higher echoes occur when the cyst is filled with keratin debris and fat.

PATHOLOGY.

A smooth, thin rim of keratinized squamous epithelium, which may have goblet cells if derived from conjunctiva, lines the cyst. The cyst wall contains hair shafts, and sweat and sebaceous glands are characteristic.

 

 

Figure 95-16 Right superomedial superficial orbital dermoid cyst in a young child.

TREATMENT AND PROGNOSIS.

Treatment consists of total excision without rupture of the capsule. The prognosis is excellent.

Mucocele

KEY POINTS.

Mucoceles arise from a primary obstruction of a paranasal sinus following trauma, sinusitis, or, rarely, a tumor.[63] Frequently, they expand into the orbit by expansion of a bony wall. Mucoceles consist of a cystic mass filled with mucus and may be bounded by an eggshell layer of bone (when they become infected, mucoceles are referred to as pyoceles). The majority of mucoceles (70%) occur in adults (aged 40–70 years), and the frontal and ethmoid sinuses are most commonly involved—rarely the sphenoid sinus.

Symptoms include headache, exophthalmos, and a palpable fluctuant mass in the medial or superomedial orbit.

ORBITAL IMAGING.

An opacified frontal or ethmoid sinus, loss of ethmoid septae, and a bony dehiscence ( Fig. 95-17 ) are observed. The cystic content shows variable density and is nonenhancing.

ECHOGRAPHY.

Echography reveals a very well-defined mass with sharp surface spikes and low internal reflectivity. Mucocele is associated with a large bony defect adjacent to a paranasal sinus.

PATHOLOGY.

The lining is composed of pseudostratified, ciliated columnar epithelium with goblet cells. The cyst content is mucoid with chronic inflammatory debris.

TREATMENT AND DIAGNOSIS.

Treatment consists of surgical excision with restoration of sinus drainage. Obliteration of the sinus with fat or muscle may be necessary to treat recurrences.

The prognosis is very good, but there is a significant rate of recurrence.

VASCULAR NEOPLASTIC LESIONS

Neoplastic lesions that arise from the vascular system include both benign and malignant tumors ( Table 95-8 ). Unlike non-neoplastic vascular lesions, which usually reflect the hemodynamic functions of the underlying vascular structures, neoplastic lesions typically manifest only a mass effect, occasionally modified by some hemodynamic characteristics. They may be well circumscribed or infiltrative.

Capillary Hemangioma (Hemangioendothelioma)

KEY POINTS.

Capillary hemangioma is a congenital hamartoma of tightly packed capillaries that typically presents during the first 6 months of life.[2] [54] [64] It is generally unilateral and usually visible on the surface, but it may lie deep in the orbit ( Fig. 95-18 ). More common in the superonasal quadrant of the upper

 

 

Figure 95-17 Anterior ethmoid sinus mucocele eroding into the orbit.

 

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lid, capillary hemangioma appears as a fluctuant mass that may involve the overlying skin as a reddish lesion. Capillary hemangiomas show rapid growth over weeks to months, followed by slow spontaneous involution over months to years.

SUPERFICIAL LESIONS.

Also known as the “strawberry nevus,” capillary hemangioma is confined to the dermis. It may be single or multiple and is generally elevated.

Symptoms include ptosis, sometimes associated with astigmatism and amblyopia.

TREATMENT AND PROGNOSIS.

Observation is warranted in most cases, since involution usually occurs. For severe cosmetic deformity or deprivation amblyopia, intralesional (40?mg/ml triamcinolone plus 6?mg/ml betamethasone) or systemic corticosteroids (1–2?mg/kg/day prednisone) may be used. Radiotherapy, yellow dye laser, and, more recently, topical corticosteroids also have been advocated. Surgery is useful for small, circumscribed lesions, but for larger ones, this may result in cosmetic compromise.

The prognosis is good; 30% of cases involute by 3 years of age, 60% by 4 years, and 75% by 7 years of age. Large lesions may not completely disappear.

DEEP LESIONS.

Deep lesions occur most frequently in the lids or posterior to orbital septum and are more common in the superonasal quadrant.

Symptoms are proptosis, displacement of the globe, subtle pulsations as a result of high vascular flow, and increasing size with Valsalva’s maneuver or crying. Secondary amblyopia may result from distortion of the globe. Large lesions may sequester platelets.

ORBITAL IMAGING.

A well-defined to infiltrating intraconal or extraconal lesion is observed, with moderate to intense enhancement. On MRI the signals are homogeneous to heterogeneous, being hypointense on T1 and hyperintense on T2 images.

 

TABLE 95-8 — FREQUENCY OF THE MOST COMMON VASCULAR ORBITAL LESIONS

Lesion

Frequency (%)

Cavernous hemangioma

50

Capillary hemangioma

18

Hemangiopericytoma

13

Lymphangioma

10

Orbital varices

5

Other

5

(Modified from Shields JA, ed. Diagnosis and management of orbital tumors. Philadelphia: WB Saunders; 1989:291–315.)

 

 

 

 

Figure 95-18 Capillary hemangioma of the lower eyelid in a young child.

Flow voids appear as hypointense regions. Moderate enhancement is seen with gadolinium.

ECHOGRAPHY.

The lesion is poorly outlined, with an irregular shape, high internal reflectivity, and an irregular acoustic structure. Sound attenuation is variable.

PATHOLOGY.

A florid proliferation of capillary endothelial cells and small capillaries is seen, with few spaces ( Fig. 95-19 ). Mitoses are common, but this is not a malignant tumor.

TREATMENT AND PROGNOSIS.

Treatment consists of observation, since many lesions will involute, although few orbital lesions completely disappear. If the lesion is large or amblyopia is present, local radiotherapy (500?cGy) or corticosteroids (systemic or local) may be indicated. If the lesion is small and well defined, surgery may be attempted.

The prognosis is excellent for vision and for life.

Cavernous Hemangioma

KEY POINTS.

Cavernous hemangioma is a benign, noninfiltrative, slowly progressive tumor of large endothelial-lined channels.[1] [2] Although it is congenital, it typically becomes symptomatic in adults (aged 20–40 years). Cavernous hemangioma is usually found in an intraconal location, more commonly in the temporal quadrant. Rarely, it may be intraosseous.

Symptoms relate to its mass effect, which produces proptosis and late motility restriction. When cavernous hemangiomas are very large, choroidal folds and decreased vision may result. The lesions may enlarge during pregnancy.

ORBITAL IMAGING.

A well-defined, oval to round, typically intraconal mass is seen with minimal enhancement. With large, long-standing lesions, molding of bone and internal calcification may occur. On MRI the lesion is isointense on T1 and hyperintense on T2 with respect to muscle. Signal voids represent calcific phleboliths. Enhancement with gadolinium is moderate.

ECHOGRAPHY.

The lesions are well circumscribed and round to oval, with high internal reflectivity and a regular acoustic structure. Vascular flow is poor.

PATHOLOGY.

The encapsulated nodular mass is dilated, with vascular spaces lined by flattened endothelial cells ( Fig. 95-20 ). Septae may contain smooth muscles cells.

TREATMENT AND PROGNOSIS.

Surgical excision is required if the lesion is symptomatic—typically, there is little or no bleeding. There is no role for radiotherapy. The prognosis is excellent for vision and life.

Lymphangioma

KEY POINTS.

Lymphangioma is a rare vascular hamartoma of lymphatic channels that is hemodynamically isolated from the

 

 

Figure 95-19 Capillary hemangioma. The tumor is composed of blood vessels of predominantly capillary size. (From Yanoff M, Fine BS. Ocular pathology, ed 5. St. Louis: Mosby, 2002.)

 

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Figure 95-20 Cavernous hemangioma. A, Clinical appearance of left exophthalmos. B, MRI shows optic nerve stretched over tumor that “lights up” in the T2-weighted image, characteristic of a hemangioma. (From a presentation by Dr. WC Frayer to the meeting of the Verhoeff Society, 1989.)

vascular system.[65] It occurs in children and teenagers, but most frequently in the first decade of life. The size of the lesion fluctuates with posture and Valsalva’s maneuver, and with upper respiratory infections.

SUPERFICIAL LESIONS.

Superficial lesions occur in the conjunctiva or lid and are visible as cystic spaces with clear fluid; they may be partially filled with blood.

DEEP LESIONS.

Symptoms with deep lesions are proptosis and diplopia. Spontaneous hemorrhage may lead to sudden enlargement and orbital pain and possible visual loss, with the formation of “chocolate cysts.”

ORBITAL IMAGING.

The orbital lesion is seen as a low-density cystic, intra- and extraconal mass, with variable enhancement. There is no vascular component on angiography. On MRI the lesion is hypointense on T1; on T2 the signal is hyperintense but may be variable, depending on the state of hemoglobin degeneration.

ECHOGRAPHY.

The orbital lesion is outlined poorly and of irregular shape, with low internal reflectivity but highly reflective internal septa.

PATHOLOGY.

Lymphangiomas show infiltrative endothelium-lined channels, with a sparse cellular framework and lymphocytes. Lymphatic follicles often are seen in the walls of the tumor. Red blood cells are not present.

TREATMENT AND PROGNOSIS.

Observation is justified in most cases. Surgery may be hazardous and lead to poor cosmetic results. If acute hemorrhage causes severe symptoms, the lymphangioma may be evacuated and partial resection or ligation attempted. Recurrences are common. The lesion shows limited radiosensitivity. The prognosis is variable. Amblyopia is common from globe compression and recurrent hemorrhage.

Arteriovenous Fistula

KEY POINTS.

Arteriovenous fistulas can be traumatic (more common in males than females, age range 15–30 years) or spontaneous (more common in females than males, age range 30–60 years).[1] [2] Symptoms depend on blood flow rate—most fistulas are associated with venous dilatation, fluid transudation, sludging, and thrombosis.

LOW-FLOW TYPE.

Low-flow fistulas usually result from dural artery–to–cavernous sinus shunts. Symptoms are chemosis, increased episcleral venous pressure, and venous dilatation.

HIGH-FLOW TYPE.

High-flow fistulas usually result from carotid artery–to–cavernous sinus shunts. Symptoms are chemosis, orbital edema, proptosis, pulsatile exophthalmos, audible bruit, secondary glaucoma, retinal vascular dilatation, papilledema, afferent pupillary defect, decreased vision, and cranial nerve palsies (third and sixth nerves most common).

PRIMARY SHUNT.

Primary shunts (mainly congenital malformations) are rare in the orbit and are usually associated with syndromes (e.g., Wyburn-Mason and Osler-Weber-Rendu).

SECONDARY SHUNTS.

Secondary shunts are located outside the orbit, usually in the cavernous sinus. Retrograde blood flow is directed forward into the orbital veins. Secondary shunts may be spontaneous (from venous thrombosis or hypertension) or secondary (from trauma). The latter are usually of the high-flow type, 40–50% causing visual loss.

ORBITAL IMAGING.

A dilated superior ophthalmic vein with enlargement of the superior orbital fissure is seen; erosion of the anterior clinoid processes occurs.

ECHOGRAPHY.

Echography shows a dilated superior ophthalmic vein and mild thickening of the extraocular muscles, with medium to high internal reflectivity from edema.

TREATMENT AND PROGNOSIS.

Resolution of small, spontaneous low-flow shunts frequently occurs from thrombosis and is seen in up to 40% of cases. Embolization is not indicated unless visual loss, glaucoma, or severe pain is present. With traumatic, high-flow shunts, spontaneous resolution is less common. The rate of visual loss is 40–50%, and intervention is therefore required. Balloon or other embolization is the treatment of choice.

With treatment, the prognosis is generally good for vision.

 

 

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743

 

 

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