Demonstration of acid-fast rods in sarcoidosis.

In 30 consecutive cases of sarcoidosis, including 18 of American origin, acid-fast bacilli were found microscopically in every instance. Patients with progressive healing and patients with caseous necrosis were excluded. The acid-fast bacilli were seen either as isolated bacilli or in groups. The staining properties and morphologic features of the observed bacilli were representative of mycobacteria. In 17 cases, the diagnosis of sarcoidosis was based on involvement of at least two organ systems, usually lymph nodes and lungs, on lack of reaction to PPD, and on laboratory and histologic findings universally accepted as diagnostic of the disease. In 13 cases, the diagnosis was based mainly on histologic features, even though bilateral adenopathy existed in several of these patients and skin tests for tuberculosis gave no reaction. Cultural verification by modern methods and identification of the mycobacterial species should be attempted systematically.