Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease): diagnosis with fine-needle aspiration in a case with nodal and nasal involvement.

Sinus histiocytosis with massive lymphadenopathy (SHML) is a rare entity characterized by the proliferation of cells belonging to the macrophage-histiocyte family, but whose exact origin is unknown. A case of SHML occurring in a 62-yr-old female is described in which the diagnosis is initially suggested by fine-needle aspiration (FNA) of a cervical node. The smears show a background of lymphocytes and plasma cells and large histiocytes with well-preserved lymphocytes in their cytoplasm (emperipolesis or lymphophagocytosis). Both nodal and extranodal (nasal mass) involvement are confirmed by surgical biopsy. The immunohistochemistry suggests that SHML cells are functionally activated macrophages. Eight months after diagnosis, the patient is clinically well, with partial improvement of lymphadenopathy.