Sinus histiocytosis with massive lymphadenopathy: A pseudolymphomatous benign disorder.Analysis of 34 cases

Thirty-four cases of sinus histiocytosis with massive lymphadenopathy (SHML) are analyzed. Most of the cases involved Negro children and were characterized by cervical lymphadenopathy, which was often bilateral, painless, and of massive proportions. Other lymph node groups were sometimes involved. Fever, leukocytosis with neutrophilia, elevated erythrocyte sedimentation rate, and hypergammaglobulinemia were common features. The involved lymph nodes showed pericapsular fibrosis; dilation of sinuses; presence of numerous intrasinusal histiocytes with abundant clear cytoplasm, occasionally multinucleated, foamy or atypical; and large collectiions of plasma cells. A striking and constant finding was the presence of many lymphocytes and other hematopoietic cells within the cytoplasm of the sinus histiocytes. The diease characteristically followed a protracted clinicl course, with eventual spontaneous regression of the lymphadenopathy and total recovery in most cases. The etiology and pathogenesis are unknown. In this regard, the most likely possibilities include a specfic infectious process and a status resulting from an immunologic deficit.