Chapter 153 – Choroidal Osteoma
JAMES J. AUGSBURGER
• Acquired benign bony tumor of choroid.
• Orange to pale yellow, geographic, plate-like juxtapapillary or circumpapillary choroidal lesion.
• Bone density of tumor detectable by ultrasonography or computed tomography.
• Bilateral in at least 20% of affected patients but unifocal in each affected eye.
• Progressive retinal degeneration that overlies the lesion.
• Secondary macular choroidal neovascularization.
The choroidal osteoma is an uncommon benign acquired bony tumor of the choroid. It was classified originally as a choristoma (a benign congenital tumor composed of normal tissue elements that do not normally occur at that site), but it is currently regarded as an acquired benign choroidal neoplasm. Its cause is unknown.
EPIDEMIOLOGY AND PATHOGENESIS
Choroidal osteoma appears to be extremely rare, but its precise frequency is unknown. It usually makes its appearance between the middle of the second decade and the end of the third decade of life. Lesions of this type occur in all ethnic groups, but over 90% of them occur in women. The stimulus for development of choroidal osteomas is not known. Affected patients do not appear to have abnormalities of calcium and phosphorus metabolism more frequently than would be expected in an unselected population of similar age and sex distribution. The fact that the vast majority of affected individuals are women suggests, however, that endocrine or hormonal factors may have a role in the development of these lesions. Occasionally, familial cases have been reported. In affected families, an autosomal dominant inheritance pattern has been observed.
Patients who have a choroidal osteoma usually present to the eye care professional with either painless progressive loss of vision over several months or years or abrupt recent blurring of central vision with micropsia and distortion. Some lesions of this type are detected initially on routine eye examination.
The typical choroidal osteoma appears as a yellowish to orange, well-defined, juxtapapillary or circumpapillary choroidal tumor ( Fig. 153-1 ). It involves one eye only in 70–80% of cases
Figure 153-1 Clinical appearance of choroidal osteoma. Note juxtapapillary location of tumor, its yellow-orange color, and prominent ramifying blood vessels on surface of lesion. The patient was a 12-year-old girl.
and both eyes in 20–30%. The surface of the tumor may be relatively flat or visibly uneven with depressions and elevations. The margins of the lesion are typically somewhat irregular in contour and sometimes have localized extensions that resemble pseudopods. Prominent inner choroidal blood vessels frequently ramify on the surface of the lesion.
If the lesion involves the macula, the visual acuity can be impaired on the basis of degeneration of the overlying retinal pigment epithelium and sensory retina. In other cases, a choroidal neovascular membrane arises from the inner surface of the lesion and produces a serous or serosanguineous macular retinal detachment that results in loss of vision.
DIAGNOSIS AND ANCILLARY TESTING
Ultrasonography and computed tomography are of particular value for confirming a presumptive diagnosis of choroidal osteoma. Because choroidal osteomas are composed of dense bone, they appear as highly reflective plate-like lesions that shadow the orbit on B-scan ultrasonography ( Fig. 153-2 ). Computed tomography accentuates the plate-like thickening of the posterior ocular wall, which is isodense with normal skeletal bone ( Fig. 153-3 ). Fluorescein angiography typically shows patchy early hyperfluorescence and late diffuse hyperfluorescence of choroidal osteomas. Indocyanine green angiography reveals generalized hypofluorescence of the mass with superimposed hyperfluorescent intralesional blood vessels in the early phase frames and diffuse hyperfluorescence of the mass in the late phase frames.
The most important lesions in the differential diagnosis of choroidal osteoma are listed in Box 153-1 .
Occasional patients with choroidal osteoma have been found to have hyperparathyroidism with secondary alterations of serum calcium and phosphorus levels. However, most individuals who
Figure 153-2 B-scan ultrasonography of choroidal osteoma. A, At 77?dB the osteoma appears as an intensely bright plate in the posterior eye wall. Note orbital shadowing behind mass. B, At 55?dB the lesion persists while most of the normal tissues are no longer evident.
Figure 153-3 Computed tomography of bilateral choroidal osteoma. Note bilateral bone-dense plate involving posterior pole of each eye. The patient was a 39-year-old woman.
Differential Diagnosis of Choroidal Osteoma
Circumscribed choroidal hemangioma
Metastatic carcinoma to choroid
Amelanotic choroidal nevus or melanoma
Neurilemoma (schwannoma) of choroid
Idiopathic or dystrophic sclerochoroidal calcification
Vitelliform macular dystrophy
Bone formation in phthisical eyes
Intrascleral cartilage in linear sebaceous nevus syndrome
Fundus lesions of Aicardi’s syndrome
Treatment Options for Choroidal Osteoma
No treatment available for tumor per se
Photocoagulation or photodynamic therapy for choroidal neovascularization associated with choroidal tumor
have a choroidal osteoma have no abnormalities of calcium and phosphorus metabolism.
Baseline Systemic Evaluation
Because of the occasional association with hyperparathyroidism, patients with choroidal osteoma should probably undergo blood testing for serum calcium and phosphorus levels.
The choroidal osteoma is composed of mature bone that replaces full-thickness choroid in a plate adjacent to or around the optic disc. The overlying choriocapillaris is sometimes preserved, but the retinal pigment epithelium and sensory retina overlying the lesion are typically disrupted. When choroidal neovascularization is present, ingrowth of a neovascular complex derived from the choroid is sometimes identified.
Lesions of this type appear to have no malignant potential. Consequently, patient management is directed at preservation of vision and, if possible, restoration of vision impaired by reversible mechanisms ( Box 153-2 ). If the mechanism of visual loss is a choroidal neovascular membrane causing an exudative macular retinal detachment, the vascular lesion may be treatable by focal retinal laser photocoagulation or photodynamic therapy. No known effective management exists for the retinal pigment epithelial and sensory retinal degeneration that occurs over macular lesions.
COURSE AND OUTCOMES
Choroidal osteomas have been recognized to enlarge slightly during several years of observation.  However, malignant transformation has not been reported.
1. Shields CL, Shields JA, Augsburger JJ. Choroidal osteoma. Surv Ophthalmol. 1988;33:17–27.
2. Cunha SL. Osseous choristoma of the choroid. A familial disease. Arch Ophthalmol. 1984;102:1052–4.
3. Guthoff R, Abramo F. Osteome der bulbuswand. Erscheinungsformen in abhängigkeit von Lage und Ausdehnung. Klin Monatsbl Augenheilkd. 1991;198: 124–8.
4. Lafaut BA, Mestdagh C, Kohno T, et al. Indocyanine green angiography in choroidal osteoma. Graefes Arch Clin Exp Ophthalmol. 1997;235:330–7.
5. Grand MG, Burgess DB, Singerman LJ, et al. Choroidal osteoma. Treatment of associated subretinal neovascular membranes. Retina. 1984;4:84–9.
6. Battaglia Parodi M, Da Pozzo S, Toto L, et al. Photodynamic therapy for choroidal neovascularization associated with choroidal osteoma. Retina. 2001;21:660–1.
7. Augsburger JJ, Shields JA, Rife CJ. Bilateral choroidal osteoma after nine years. Can J Ophthalmol. 1979;14:281–4.
8. Aylward GW, Chang TS, Pautler SE, Gass JD. A long-term follow-up of choroidal osteoma. Arch Ophthalmol. 1998;116:1337–41.