A report of a patient with the rare syndrome of sinus histiocytosis with massive lymphadenopathy is presented here. This patient is unusual in several respects, including his longevity after diagnosis, the presence of a benign monoclonal gammopathy, and the characterization of his cutaneous infiltrates by immunofluorescent monoclonal antibody markers. A review of the literature on sinus histiocytosis with massive lymphadenopathy, with particular emphasis on cutaneous manifestations, is given.