title: Immunoblastic sarcoma of T- and B-cell types: morphologic description and comparison.
abstract: Immunoblastic sarcoma (IBS) is a large cell lymphoma conceptually related to transformed T and B lymphocytes of the extrafollicular compartment of the immune system (immunoblasts). This light microscopic study of a series of 47 immunologically defined cases of IBS was undertaken in an attempt to define more precisely the morphologic features of the T- and B-cell subtypes. A remarkable morphologic spectrum characterized T-IBS (31 cases), which could be divided into two main groups: 1) tumors composed of varying mixtures of small, medium-sized, and large transformed cells; and 2) tumors with more homogeneous populations of medium-sized or large transformed cells. These cells, in all sizes, generally had abundant pale-staining cytoplasm, delicate nuclear membranes, finely dispersed chromatin, and one to several, small or medium-sized, prominent nucleoli. A distinctive background of small, irregular lymphocytes was frequently present. Plasmacytoid differentiation, seen most consistently as amphophilic staining of the cytoplasm, generally characterized B-IBS (16 cases). B-IBS similarly showed a morphologic spectrum that occurred in two main forms: 1) tumors consisting of a spectrum of transformed cells, with the smaller cells often showing the most striking plasmacytoid differentiation; and 2) tumors consisting predominantly of medium-sized to large transformed cells with varying degrees of plasmacytoid differentiation. With this constellation of features, all but two cases of T-IBS and one case of B-IBS were morphologically distinguishable.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000954:Antigens, Surface; D001402:B-Lymphocytes / Q000473:pathology*; D001706:Biopsy; D002471:Cell Transformation, Neoplastic; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000145:classification* / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D044469:Racial Groups; D013601:T-Lymphocytes / Q000473:pathology*
chemical_list: D000954:Antigens, Surface