The diagnosis of sarcoidosis.

The diagnosis of sarcoidosis depends on the clinical and radiologic features along with histologic evidence of epithelioid-cell granulomas on biopsy. The amount of histologic support required varies inversely with the certainty with which the pattern of clinical features is recognized. It is essential to exclude other recognized causes of granulomatous disease. On the basis of our experience and that of other workers, we believe that sarcoidosis must be considered in the differential diagnosis when optic nerve thickening is encountered on CT, MRI or echography. Chest roentgenography is the easiest way to confirm the diagnosis. However, as many as 15% of patients will have a normal x-ray film, and other tests may be needed to help confirm the diagnosis. Biopsy of the involved tissues may be the only way to make the diagnosis. Once a provisional diagnosis is made, investigation for systemic sarcoidosis should include chest roentgenography, determination of the serum ACE level, 67Ga scanning, pulmonary function studies, testing for delayed skin reactions (with tuberculin, C. albicans, Trichophyton and mumps virus) and blood studies (determination of the erythrocyte sedimentation rate and levels of immunoglobulins, albumin, calcium and alkaline phosphatase). Finally, conjunctival biopsy is simple to do and is quite useful in supporting the diagnosis if no other tissue is readily available.