Cyclin D1-negative blastoid mantle cell lymphoma exhibiting cleaved to bilobated cytomorphology.

A 66-year-old man presented with a white blood cell count of 62.63 10 /L. Peripheral blood (PB) smear showed 80% smallto medium-sized atypical lymphoid cells with irregular to cleaved (panel A; original magnification 3500, Wright-Giemsa stain) or binucleated nuclear contours, and slightly condensed chromatin (panel B; original magnification 31000, Wright-Giemsa stain). Bone marrow (BM) aspirate (panel C; original magnification 3500, Wright-Giemsa stain) and biopsy (panel D; original magnification3400, hematoxylin and eosin stain) showed ;70% atypical lymphoid cells with similar features to those of PB. These lymphoid cells were positive for CD20 (panel E; original magnification 3200) and CD5 (panel F; original magnification 3100), negative for CD3 (panel G; original magnification3100) and cyclin D1 (not shown), but showed strong nuclear immunoreactivity for SOX11 (panel H; original magnification3400) and;70% proliferation index by Ki-67 (panel I; original magnification3200). Flow cytometry of PB and BM showed l-restricted monotypic B cells, positive for FMC-7 but negative for CD23. Conventional karyotyping showed 46,XY[20], and fluorescence in situ hybridization analysis of BM showed no cyclin D1 orMYC rearrangements. A diagnosis of cyclin D1–negative blastoid mantle cell lymphoma (BMCL) was established.