MUCOSAL MANTLE CELL (CENTROCYTIC) LYMPHOMAS

The morphology, phenotype, genotype and clinical behaviour oi. four ca ses of mantle cell lymphoma (centrocytic lymphoma) presenting primaril y in mucosa (two gastric, one in large bowel and one tonsillar) are re viewed. Their relationship with the broader group of mantle cell and m ucosa-associated lymphoid tissue (MALT) lymphomas is also discussed, A ll four tumours showed a monomorphic picture of mantle cells (centrocy tes) arranged in a diffuse, or vaguely nodular, pattern, Scattered non -neoplastic germinal centres were entrapped within the tumour cells, a lthough there was no follicular colonization, in two cases distinct ep ithelial infiltration by tumour cells was observed, All four tumours h ad a CD19, CD20, CD5, IgD, Leu8 immunophenotype, whereas KiM1P and CD1 0 expression were absent, DRC antibody showed loose aggregates of dend ritic cells in three of four cases, Three cases showed PRAD-1/Cyclin D 1 overexpression by Northern blot analysis. Although we were not able to detect bcl-1 rearrangement in the major translocation cluster (MTC) breakpoint, the possibility of bcl-1 rearrangement involving other cl uster breakpoints cannot be ruled out, The four cases evolved as a dis seminated disease, involving either peripheral lymph nodes, spleen or bone marrow, The biological behaviour of mantle cell lymphoma presenti ng in mucosa appears, irrespective of localization or macroscopic pres entation, similar to that of nodal mantle cell lymphoma, Their tendenc y to dissemination contrasts with MALT lymphomas, which tend to remain localized, and from which mucosa mantle cell lymphoma must be disting uished. The presence of lymphoepithelial lesions does not seem to be a useful differential feature, since occasional epithelial infiltration was seen in two cases, Reactivity with CD5 appears to be especially u seful in distinguishing these, since all four cases were clearly posit ive, in contrast with what is usually found in MALT lymphomas.