The diagnosis and differential diagnosis of cutaneous sarcoidosis

Abstract

Sarcoidosis and the other granulomatous diseases, such as syphilis, are recognized as capable of many clinical and pathologic presentations. The capacity of the clinician to make a diagnosis depends upon the basic knowledge of the protean forms of the granulomatous diseases. Good examples of such diseases have been the recent cases of reported syphilis that presented as clinical and histopathologic sarcoidosis. 2–4 Recognition that systemic sarcoidosis may involve the skin secondarily and that no specific laboratory or other tests exist to make a specific confirmation of the diagnosis limits the capacity of the physician: all of the major granulomatous diseases (eg. syphilis, tuberculosis, leprosy, and the deep fungus infections) involve multiple organs with a granulomatous reaction. The diagnosis of sarcoidosis must be approached by eliminating specific infectious causes. Sarcoid-like changes in the skin with microscopic epithelioid granulomas are not sufficient for the diagnosis of systemic sarcoidosis. We will discuss both the clinical and histologic appearances of sarcoidosis. We also will outline the biochemical and immunologic abnormalities as they apply to the diagnosis of cutaneous sarcoidosis. A basic clinical skepticism concerning the diagnosis of sarcoidosis is always appropriate.