Walsh & Hoyt: Sarcoidosis: Pathology

The primary pathologic feature of sarcoidosis is a noncaseating granuloma. The predominant cells within a sarcoid granuloma are epithelioid cells, which are arranged compactly ina whorled configuration. A small area of fibrinoid necrosis may be present in the center of the whorl. Also present in sarcoid granulomas are Langhans and foreign-body type giant cells. These cells result from fusion of macrophages and sometimes contain cytoplasmic inclusions. Some of the inclusions are composed of nonspecific crystalline material. Others lamellar concretions called Schaumann bodies (or conchoidal bodies) are composed of calcium and iron. They may enlarge up to 100 m in diameter and eventually burst out of the giant cell so that they lie within the intercellular space. Although Schaumannbodies may occur inother diseases, their presence in the appropriate clinical and radiographic setting is highly suggestive of sarcoidosis. Sarcoid granulomas are surrounded by a rim of lymphocytes, most of which are CD4 T-helper/inducer cells.