Harrison’s Manual of Medicine
A systemic granulomatous disease of unknown etiology. Affected organs are characterized by an accumulation of T lymphocytes and mononuclear phagocytes, noncaseating epithelioid granulomas, and derangements of normal tissue architecture.
Mononuclear cells, mostly T helper lymphocytes and mononuclear phagocytes, accumulate in affected organs followed by formation of granulomas. It does not appear that this process injures parenchyma by releasing mediators; rather, organ dysfunction results from the accumulated inflammatory cells distorting the architecture of the affected tissue. Severe damage of parenchyma can lead to irreversible fibrosis.
In 10–20% of cases, sarcoidosis may first be detected as asymptomatic hilar adenopathy. Sarcoid manifests clinically in organs where it affects function or where it is readily observed. Onset may be acute or insidious.
Acute sarcoid—20–40% of cases. Two acute syndromes: Lofgren’s syndrome: hilar adenopathy, erythema nodosum, acute arthritis presenting in one or both ankles spreading to involve other joints; Heerfordt-Waldenström syndrome: parotid enlargement, fever, anterior uveitis, facial nerve palsy.
Insidious onset—40–70% of cases. Respiratory Sx most common presenting feature with constitutional or extrathoracic Sx less frequent.
Disease manifestations of sarcoid include:
Constitutional symptoms—fever, weight loss, anorexia, fatigue.
Lung—most commonly involved organ; 90% with sarcoidosis will have abnormal CXR some time during course. Features include: hilar adenopathy, alveolitis, interstitial pneumonitis; airways may be involved and cause obstruction to airflow; pleural disease and hemoptysis are uncommon.
Lymph nodes—intrathoracic nodes enlarged in 75–90% of pts.
Skin—25% will have skin involvement; lesions include erythema nodosum, plaques, maculopapular eruptions, subcutaneous nodules, and lupus pernio (indurated blue-purple shiny lesions on face, fingers, and knees).
Eye—uveitis in ~25%; may progress to blindness.
Upper respiratory tract—nasal mucosa involved in up to 20%, larynx 5%.
Bone marrow and spleen—mild anemia and thrombocytopenia may occur.
Liver—involved on biopsy in 60–90%; rarely important clinically.
Kidney—parenchymal disease, nephrolithiasis secondary to abnormalities of calcium metabolism.
Nervous system—cranial/peripheral neuropathy, chronic meningitis, pituitary involvement, space-occupying lesions, seizures.
Heart— disturbances of rhythm and/or contractility, pericarditis.
Musculoskeletal—dactylitis, chronic mono- or oligoarthritis of knee, ankle, PIP.
Other organ systems affected: endocrine/reproductive, exocrine glands, GI.
Hx and physical exam to rule out exposures and other causes of interstitial lung disease.
CBC, Ca2+, LFTs, ACE, PPD and control skin tests.
CXR, ECG, PFTs.
Biopsy of lung or other affected organ.
Bronchoalveolar lavage and gallium scan of lungs may help decide when treatment is indicated and may help to follow therapy; however, these are not uniformly accepted.
Made on basis of clinical, radiographic, and histologic findings. Biopsy of lung or other affected organ is mandatory to establish diagnosis before starting therapy. Transbronchial lung biopsy usually adequate to make diagnosis. No blood findings are diagnostic. Differential includes neoplasms, infections, HIV, other granulomatous processes.
Many cases remit spontaneously; therefore, deciding when treatment is necessary is difficult and controversial. Significant involvement of the eye, heart, or CNS or progressive lung disease is the main indication for treatment. Glucocorticoids are mainstay of therapy. Usual therapy is prednisone 1 (mg/kg)/ d for 4–6 weeks followed by taper over 2—3 months. Anecdotal reports suggest that cyclosporine may be useful in extrathoracic sarcoid not responding to glucocorticoids.
Most pts with acute disease are left with no significant sequelae. Overall, 50% of pts with sarcoid have some permanent organ dysfunction; in 15–20% disease remains active or recurrent; death directly due to disease occurs in 10% of cases. Respiratory tract abnormalities cause most of the morbidity and mortality related to sarcoid.
For a more detailed discussion, see Crystal RG: Sarcoidosis, Chap. 318, p. 1969, in HPIM-15.