Plasma cell myeloma with lymphoplasmacytic morphology and cyclin D1 expression, an uncommon variant.

The genetic complexity of multiple myeloma is due in part to the accumulation of mutations, with primary and secondary events. One such secondary event is the development of a gene mutation that may result in overexpression of cyclin D1. The pathway involving cyclin D1 is intricately involved in cell cycle regulation from the G1 to S phase, and alterations may contribute to tumorigenesis. We present a case of cyclin D1-positive multiple myeloma with lymphoplasmacytic morphology and discuss potential diagnostic pitfalls and effects on prognosis.