Summary Mantle cell lymphoma (MCL) is an aggressive lymphoid tumour characterized by the translocation t(11;14)(q13;q32) and a poor clinical outcome (median survival: 3–4 years). Recent studies revealed that increased proliferation of the tumour cells and certain chromosomal aberrations, such as deletions of 17p13 and 9p21 represent major adverse biological markers in this disease, although the molecular targets of chromosomal imbalances in MCL have not been identified for the large majority of loci affected. To correlate histomorphological and proliferation features of MCL with genetic findings, we investigated 223 MCL by fluorescence in situ hybridization (FISH) (n = 157) and/or classical cytogenetic banding analysis (n = 129). FISH analysis turned out to be distinctly more sensitive in the delineation of aberrations. Complex karyotypic alterations were associated with higher proliferation indices and inferior prognosis. A comprehensive analysis of biological features including genetic alterations in MCL by hierarchical clustering resulted in the delineation of four tumour subgroups differing with respect to their genetic constitution and suggesting different transformation or progression pathways. Moreover, in one of the groups identified, a more indolent clinical behaviour was associated with few secondary aberrations and fewer known high‐risk chromosomal aberrations, which points to the importance of the quality of karyotypic evolution in MCL tumours.

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