CD5-negative mantle cell lymphoma shows a less aggressive outcome and variable SOX11 staining

Abstract

Mantle cell lymphoma (MCL) is an uncommon B-cell lymphoma that prototypically expresses CD5, but a small subset is CD5 negative. The clinical significance of CD5 negativity is not yet well-elucidated. This case series aims to contribute to the understanding of CD5-negative MCL by looking at specific markers and outcome in our cases with long-term follow-up. Eight cases of CD5-negative MCL were identified in the case files at the Massachusetts General Hospital from 1978 to 2016. Clinicopathological characteristics were evaluated, including immunohistochemical stains for cyclin D1, SOX11, Ki67, and p53. Patients initially presented with involvement of lymph nodes and spleen (n = 4), sinonasal or oral mucosa (n = 2), orbital soft tissue (n = 1), and salivary gland (n = 1). On histology, the cases all showed classic MCL morphology, with a monotonous population of medium-sized cells with irregular nuclear contours. The cases were positive by immunohistochemistry for cyclinD1 (8/8 cases), essentially negative for p53 staining (8/8 cases), and mostly positive for SOX11 (5/8 cases). All cases had a low Ki67 proliferation rate (<5%). Long-term clinical follow-up on five cases showed that four patients had a clinical course complicated by multiple relapses to the skin, soft tissue, liver, and bone marrow. Seven cases with available follow-up showed an average survival of 121 months (SD 86 months), with no detectable survival difference between the SOX11 positive and negative cases. CD5-negative MCL is an uncommon subtype of MCL that overall appears to have a better prognosis and longer overall survival than classic MCL, despite SOX11 expression. The cases also show little p53 expression and a low Ki67 proliferation index.

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