[Malignant histiocytosis simulating histiocytosis with massive sinusal lymphadenopathy, on the first lymph node biopsy (author's transl)].

The case of a 36 year old man who presented prominent bilateral cervical lymphadenopathies is reported. The diagnosis of sinus histiocytosis with massive lymphadenopathy (Rosai and Dorfman, 1969) was retained on account of a massive hyperplasia of foamy histiocytes with PAS + inclusions, lipidic storage and hemocytophagy in the sinuses and cords of the lymph nodes. The patient died after 34 months evolution. At the autopsy an important proliferation by large atypical sometimes multinucleated cells in the lymph nodes, liver, bone and spleen was found, as observed in malignant histiocytosis. The ultrastructural study confirmed the histiocytic nature of the cells. The interest of immunohistochemical studies on paraffin embedded material with characterization of tumor histiocytes with lysozyme and alpha 1 antichymotrypsin is discussed. This report described an unusual form of malignant histiocytosis simulating on his early phase sinus histiocytosis with massive lymphadenopathy.