The cytomorphological spectrum of mantle cell lymphoma is reflected by distinct biological features

Mantle cell (centrocytic) non-Hodgkin's lymphoma (MCL) is a malignant tumour with unique biological features. The pathogenesis of MCL seems to be strongly associated with aberrant function of the cell cycle. 110 cases of MCL have been analysed for their cytomorphological features, mitotic and proliferation indices, bcl-1 rearrangements, p53 expression patterns and DNA content by both interphase cytogenetic as well as DNA flow cytometric analyses. According to cytomorphology, three subtypes were recognized: a common, a lymphoblastoid and a pleomorphic variant of MCL. Blastic MCL subtypes were characterized by distinctly elevated mitotic and proliferation indices, frequent bcl-1 rearrangements at the MTC locus, and overexpression of p53. The most interesting finding, however, was a striking tendency of blastoid MCL subtypes to harbour chromosome numbers in the tetraploid range, a feature clearly separating these neoplasms from other types of B-cell NHL and possibly being related to its unphysiological expression of cyclin D1. Although characterised by a uniform immunophenotype and common biological background, MCL shows a broad spectrum of morphological features ranging from small cell to blastic types, and this spectrum is mirrored by distinct biological features.