title: Immunohistology and aetiology of histiocytic necrotizing lymphadenitis. Report of three instructive cases.
abstract: Three cases of histiocytic necrotizing lymphadenitis are reported. Two patients came from Vietnam and the third from Greece. In all cases there was infection with yersinia enterocolitica of serogroup 9 or 3. Cervical lymph nodes were examined. Histologically, the characteristic necrosis developed in large foci of so-called T-associated plasma cells. Immunological analysis showed that these cells have characteristic markers of helper/inducer T cells, but do not express sheep erythrocyte receptors. The T-associated plasma cells perished by pyknosis and were then phagocytosed and digested by macrophages, which were present in large numbers. The necrotic areas were exclusively located in hyperplastic T regions. The B-cell system did not play a role in the reaction. T-associated plasma cells have been renamed 'plasmacytoid T cells' because they contain abundant rough endoplasmic reticulum ('plasmacytoid') and show immunological features of T cells. It appears likely that plasmacytoid T cells are the counterparts of plasma cells of the B-cell system that secrete lymphokines instead of immunoglobulin.
mesh_terms: D000328:Adult; D005260:Female; D005860:Germany, West; D006115:Greece / Q000208:ethnology; D006644:Histiocytes; D006801:Humans; D007124:Immunoenzyme Techniques; D008199:Lymphadenitis / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*; D008297:Male; D010950:Plasma Cells / Q000473:pathology; D006377:T-Lymphocytes, Helper-Inducer / Q000473:pathology; D014744:Vietnam / Q000208:ethnology; D015009:Yersinia Infections / Q000453:epidemiology / Q000473:pathology*; D015008:Yersinia enterocolitica