Primary cutaneous B-cell lymphoma in Japanese patients.

Primary cutaneous B-cell lymphoma (PCBCL) is a rare group of lymphoproliferative disorders. There have been few reports of Japanese patients with PCBCL, so the present study investigated the clinicopathological and immunological features and Bcl-2 gene rearrangement and protein expression in 28 Japanese patients with PCBCL. According to the Revised European-American Lymphoma (REAL) classification, there were 25 diffuse large B-cell lymphomas (DLBCL), one Burkitt type lymphoma, one lymphoblastic lymphoma and one marginal zone cell lymphoma. Of the 25 DLBCL, 17 were in males and eight in females, with an average age of 69.4 years. Follow-up data were available in 19 cases of DLBCL of which seven died and 12 were alive. The overall 5-year survival rate was 61%. Cases of DLBCL involving the legs were found to have poorer clinical outcomes; two of four cases with leg lesions died, with a mean survival of 13 months. Of 14 cases with non-leg lesions, four died, and the mean survival was 38.9 months. Only one case of Burkitt type lymphoma was CD10 positive. Bcl-2 rearrangement was not observed in 13 cases studied by polymerase chain reaction. Bcl-2 expression was observed in nine of 13 cases studied. All five cases with leg lesions exhibited Bcl-2 expression, but four of six cases with non-leg lesions also expressed the protein. These results show that DLBCL is the most frequent subtype of PCBCL in Japanese patients and that the prognosis of Japanese patients with DLBCL is worse than that of reported European cases. The study also found that PCBCL was frequently associated with Bcl-2 expression, which was not site-confined, and that there was no evidence for a follicular center origin of PCBCL.