The recent publication reviewing the updated WHO classification commented on the presence of cyclin D1-positive cells in the proliferation centres (PC) of small lymphocytic lymphoma/chronic lymphocytic leukaemia (SLL/CLL). The figure quoted was 30%, which appeared higher than our experience. To assess cyclin D1 expression in PC of SLL/CLL cases, we performed a review of SLL/CLL cases diagnosed at the Royal Marsden Hospital between 1996 and 2009. Of 105 SLL/CLL cases, 16.2% showed expression of cyclin D1 in PC with none carrying the translocation t(11;14)(q13;q32). Our study and a review of the published literature suggest that this phenomenon occurs with a significantly lower prevalence than that described in the recent review of the updated WHO classification. We confirm that cyclin D1 expression is confined to PC with the typical small lymphocytes being negative. This finding is apparently unrelated to the translocation involving CCND1 and IGH genes.
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Handling editor Mary Frances McMullin.
Contributors LSTM and AW analysed the data and wrote the paper; ADA analysed the data and revised the manuscript critically; NP performed immunohistochemical staining, data collection and revised the manuscript critically.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Royal Marsden Hospital Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
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