Sinus histiocytosis with massive lymphadenopathy in a Japanese adult with unusually elevated EBV antibody titers.

A 35-year-old Japanese male was presented with massive lymphadenopathy in bilateral preauricular and submandibular regions for five years' duration without any complaints despite of no specific treatments. Laboratory examinations revealed neurtrophilia, elevated BSR, hypergammaglobulinemia with elevated IgG and IgM, positive CRP and RA, low percentage of T-cells in peripheral blood, impaired PHA blast transformation, and elevated EBV titers against viral capsid, early and nuclear antigens. Biopsy specimens demonstrated massive histiocytosis with hemophagocytosis in the sinuses and predominant mature plasma cells in the medulla, which were fairly well consistent with "sinus histiocytosis with massive lymphadenopathy" (ROSAI and DORFMAN). Ultrastructural study revealed histiocytes exhibiting avid phagocytosis of blood cells, epithelioid histiocytes with poor phagocytic activity, foamy storage histiocytes loaded with a large number of osmiophilic lipid granules and giant cells of various types. Pathogenesis of this apparently benign disease entity was briefly discussed, and its refractoriness against any specific therapy was emphasized.