Sarcoidosis



Sarcoidosis is a systemic disease of unknown etiology characterized by abnormal T cell func­tion and noncaseating granulomas found diffusely throughout the body. It occurs most commonly in the third and fourth decades, is slightly more likely in women, and is approximately ten times more frequent in black people in the United States.

Most of the dysfunction associated with sar­coidosis results from the physical presence of the granulomas in the tissues, although systemic signs of inflammation may also be present. Organs commonly involved include the lungs, skin, lymph nodes, liver, spleen, eyes, joints, central nervous system, and muscle . The presenting symptoms are quite variable, although in the United States 50 per cent of patients will present with pulmonary disease, 25 per cent with constitutional symptoms, and 7 per cent with ex­trapulmonary involvement, and the remainder are asymptomatic and disease is discovered during routine examination.
Diagnosis depends on the finding of nonca­seating granulomata in the setting of a character­istic clinical picture with typical radiographic findings, in the absence of another specific cause of granulomatous disease, such as tuberculosis, fungal disease, carcinoma, and lymphoma. His­tological confirmation is most commonly ob­tained by a transbronchial biopsy during bron­choscopy. Conventional chest x-ray staging is as follows; stage O, normal film, stage 1, bilateral hilar adenopathy; stage 2, adenopathy plus pul­monary infiltrates; and, stage 3, pulmonary infil­trates alone. There is no evidence that staging has anv relationship to the natural progression of dis­ease. Rarely, the x-ray may show multiple nodules similar to those seen with a metastatic tumor or a pleural effusion. Nonspecific laboratory abnor­malities include hypercalcemia, anemia, hyper­gammaglobulinemia, and an elevated angioten-sin-converting enzyme level. Skin test anergy is usually present in association with lymphopenia and decreased number and function of peripheral blood T cells.

The disorder is usually self-limited, with com­plete resolution of symptoms and chest x-ray changes within a year or two. A minority have a persistent mild abnormality with some fibrotic changes on chest x-ray. Approximately 10 per cent develop severe progressive disease with pro­gressive pulmonary fibrosis or significant extra­pulmonary involvement.
Because of the self-limiting nature of the dis­ease, treatment is usually reserved for patients with significant symptomatic abnormalities of pulmonary function and with granulomas in the eye or central nervous system, where scarring will lead to significant problems. Corticosteroids are quite effective in ameliorating the acute granu­lomatous inflammation, but their efficacy in al­tering the long-term prognosis is unproven.