CD5+ true SLL/CLL with plasmacytic differentiation and an unusual 1p36 translocation: case report and review of the literature.

Lymphoplasmacytic lymphoma (LPL) and small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL)are distinct clinicopathologic entities. Although some cases of SLL/CLL may show plasmacytic differentiation and be associated with monoclonal immunoglobulin in serum, such cases appear to be very rare, and if plasma cell differentiation were marked, differentiation of SLL/CLL from LPL could be difficult. We report a rare case of true CD5-positive small lymphocytic lymphoma/chronic lymphocytic leukemia with unequivocal plasmacytic differentiation. This case also showed an abnormality of chromosome 1p36 not previously described in small lymphocytic lymphoma/chronic lymphocytic leukemia.