Among chronic lymphoproliferative disorders other than MCL, only 1 atypical chronic lymphocytic leukemia (CLL) with a t(11;14) translocation and bcl-1 rearrangement and the 2 hairy cell leukemias (HCLs) analyzed showed upregulation of PRAD-1 gene.
Data showed the transcriptional levels of SOX11 and cyclin D1 were higher for the mantle cell lymphoma (MCL) samples compared with chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), hairy cell leukemia (HCL), splenic marginal zone lymphoma (SMZL), and healthy collators.
In contrast, one case of small lymphocytic lymphoma/chronic lymphocytic leukemia (1/18; 6%) and one case of hairy cell leukemia (1/5; 20%) expressed cyclin D1 protein.
Its expression is independent of cyclin D1 (except for weak expression in hairy cell leukemias) and unlikely to be due to translocations in lymphoid neoplasia.
Since expression of cyclin D1 in normal lymphoid cells is very low to undetectable, and only hairy-cell leukemia and very few other B-cell lymphomas show expression, immunohistochemistry for cyclin D1 provides an excellent marker for MCL.
Sox11 was then examined in plasma cell myeloma and hairy cell leukemia as a subset of plasma cell myeloma carry t(11;14) and overexpress cyclin D1, and cyclin D1 is overexpressed in a subset of hairy cell leukemia independent of t(11;14).
Strong cyclin D1 mRNA overexpression was detected in mantle cell lymphomas (23 of 23), hairy cell leukemias (5 of 19), and multiple myelomas (7 of 23) with particularly high levels in 2 of the latter cases.
To investigate whether the CCND1 gene is involved in HCL, we performed IHC on a series of 22 cases using formalin-fixed paraffin embedded splenectomy specimens.