A syringotropic variant of cutaneous sarcoidosis: Presentation of 3 cases exhibiting defective sweating responses

BackgroundAlthough nodular collections of epithelioid histiocytes and multinuclear cells can be present at all levels of the dermis in cutaneous sarcoidosis, sarcoidal granulomas characterized by marked syringotropism of epithelioid histiocytes have not been previously reported to our knowledge.ObjectiveWe sought to determine whether syringotropic sarcoidosis bears characteristic clinical and histologic features and exhibits defective sweating responses.MethodsWe investigated the clinical, histologic, and immunohistochemical features of syringotropic sarcoidosis, and sweating responses to thermal stress in 3 patients.ResultsMultiple erythematous patches/plaques predominantly affected the extensor aspect of the lower legs and thighs. Immunohistochemical analyses of the sweat glands surrounded by syringotropic granulomas exhibited profoundly decreased expression of dermcidin and aquaporin 5, both of which are constitutively expressed in sweat glands of control subjects, suggesting functional defects. Indeed, sweating responses to thermal stress were markedly decreased in the involved area, as compared with those in the uninvolved area and in healthy control subjects.LimitationsThere were a limited number of cases in our study.ConclusionA syringotropic variant of cutaneous sarcoidosis might be a distinct entity clinically and histologically or represent an abortive variant.