The coexistence of scleroderma and malignancy is well documented. The case presented here is unique, however, as it is the first report of the occurrence of diffuse histiocytic lymphoma and pemphigus vulgaris in a patient with scleroderma. Because of this unusual triad of diseases, the possibility of a common pathogenetic basis was examined. A review of the literature confirms that each disorder does have immunologic abnormalities. It is suggested that an aberrant immune response, specifically impaired T-cell function, is responsible for the emergence of disease of this patient.