Sinus histiocytosis with massive lymphadenopathy. A nodal and extranodal proliferation of S-100 protein positive histiocytes?

Four cases of sinus histiocytosis with massive lymphadenopathy (SHML) from Finland were studied clinically and immunohistologically. Three patients had histologically verified extranodal manifestations that often caused the most prominent clinical symptoms. Upper respiratory tract obstruction resulting from SHML lesions was present in two cases, multiple bone lesions in one case, and skin lesions in one case.