[Morphological, morphometrical, and immunophenotypic characteristics of primary mediastinal B-cell lymphosarcoma].
AIM: To define histological, cytological, computer-morphometric and immunophenotypical features of primary mediastinal B-cell lymphosarcoma. MATERIAL AND METHOD: The study enrolled 43 patients with primary mediastinal B-cell lymphosarcoma (PMBCL) treated in Hematological Research Center from 1994 to 2002. The examination included morphological and immunophenotypical tests, computer morphometry of the cells by histological sections. RESULTS: PMBCL is represented by a composite population of cells of a giant, large and small size (nuclear areas 76.24 +/- 19.99, 37.77 +/- 8.0 and 17.12 +/- 4.34 mcm2. Three types were identified: giant-cell, large-cell and small-cell. A giant-cell type is represented by large and giant cells comprising, on the average, 44 and 31% of overall number of lymphoid cells. A large-cell type is primarily represented by large lymphoid cells (62% of the lymphoid population). Small-size type is represented by small cells (72% of cells). Frequent histological signs are diffuse sclerosis and focal necrosis. Tumor cells have B-cell nature. In the giant and large cell type more than 70% cells express PCNA, in the small cell type--less than 30%. Expression of activation marker CD30 is observed in 18% cases in the giant and large cell types. CONCLUSION: PMBCL is a morphologically heterogenous disease represented by combination of giant, large and small cells with immunophenotypically B-cell nature characterized in a giant cell and large cell type by prominent but in a small cell and large cell type by insignificant proliferative activity. CD30 expression is observed only in giant cell and large cell types.