CD5 and B-cell chronic lymphocytic leukemia: MCL cells overexpress cyclin D1 owing to a t(11;14) chromosomal DNA translocation, although there also exist few MCL cases lacking these biomarkers.1 MCL co-express CD19, CD20 and CD5 antigens with chronic lymphocytic leukemia (CLL), which has many more indolent clinical outcomes, and is typically marked with leukemization.