Cytogenetic studies of composite lymphomas: monocytoid B-cell lymphoma and other B-cell non-Hodgkin's lymphomas

Monocytoid B-cell lymphoma (MBCL) is a newly recognized, morphologically and immunologically distinct, low-grade B-cell neoplasm that may exist as a pure morphologic entity or as a component of a composite lymphoma. To determine whether cytogenetic abnormalities exist in cases of MBCL, fresh tissue from four lymphoma specimens in which MBCL was a substantial component were analyzed by classic cytogenetics; no pure MBCL cases were available for study. One monoclonal neoplastic population was found in each case by immunophenotyping studies and classic cytogenetics. Clonal cytogenetic abnormalities included -X or +X, t(14;18)(q32;q21), del(6q), t(11;14)(q13;q32), dup(12q), dup(1q), t(2;3)(q13;q29), and der(8)t(8;9)(p11.2;q13). The abnormal clone usually reflected the underlying lymphomatous process, namely, follicular lymphoma [t(14;18)], mantle cell lymphoma [t(11;14)], or small lymphocytic lymphoma (partial trisomy 12). There were no cytogenetic abnormalities common to all neoplasms. Taken together, the cytogenetic and immunologic data suggest that although MBCL may exist as a pure entity, it also may commonly represent a morphologic variant or a component of other primary lymphomatous processes.