Mantle Cell Lymphoma Misdiagnosed as Chronic Lymphocytic Leukemia: Optimization of Diagnostic Approach

Mantle cell lymphoma (MCL) is a mature B-cell non-Hodgkin lymphoma that is relatively uncommon. MCL is an aggressive lymphoma and at times can share many features with chronic lymphocytic leukemia (CLL). CLL is positive for CD5+ (in 80% of cases), CD20+ (95%) and CD23+ (85%). MCL is also positive for CD5+ (80%) and CD20+ (94%), but generally negative for CD23-. However, there are cases of CD23 positive MCL which can lead to misdiagnosis. Cyclin D1 is more specific than CD markers, but is positive in approximately 85-90% of cases. Thus for 15% of cases this test is also not reliable to diagnose MCL. For example, there are reports of Cyclin D2 and Cyclin D3 involvement instead of the more commonly known Cyclin D1. The same is true for t (11;14) studies by Fluorescence in situ hybridization (FISH) for MCL. Though it is a rare entity, there are known cases of t (11;14) negative MCL. In cases such as these, it may be difficult to correctly diagnose MCL. Therefore, it is important to have an understanding of the similarities and differences of these two diseases and to be aware of the less commonly used tests to help differentiate between MCL and CLL.