Small B-cell neoplasms with typical mantle cell lymphoma immunophenotypes often include chronic lymphocytic leukemias

Area of Science:

• Hematology
• Oncology
• Immunophenotyping

Background:

• Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) are CD5+ small B-cell neoplasms (SBCNs).
• Flow cytometry immunophenotyping aids in differentiating CLL from MCL.
• The diagnostic accuracy of a typical MCL immunophenotype for distinguishing MCL from CLL is not well-established.

Purpose of the Study:

• To evaluate how well a typical MCL immunophenotype distinguishes MCL from CLL.
• To investigate the cytogenetic and immunophenotypic characteristics of SBCNs with MCL immunophenotypes.

Main Methods:

• Analysis of 28 SBCN cases with typical flow cytometry-determined MCL immunophenotypes.
• Fluorescence in situ hybridization (FISH) for t(11;14) translocations and other cytogenetic abnormalities.
• Morphologic and immunophenotypic comparison between t(11;14)-positive and negative cases.

Main Results:

• 57% of cases had t(11;14) translocations, consistent with MCL.
• 32% lacked t(11;14) but had CLL-associated cytogenetic abnormalities.
• No significant morphologic or immunophenotypic differences were observed between t(11;14)-positive and negative cases.

Conclusions:

• A significant proportion of blood-based SBCNs with typical MCL immunophenotypes may represent phenotypically atypical CLL.
• These findings have important clinical implications for accurate diagnosis and patient management.