Mantle Cell Lymphoma Involving Skin: A Clinicopathologic Study of 37 Cases.

Mantle cell lymphoma (MCL) rarely involves the skin and the histologic and immunohistochemical features of this neoplasm at this site are under described. In this study, we report 37 skin specimens involved by MCL, representing 1.4% of total MCL biopsy specimens in our institution. The median age at time of skin involvement was 66 years (range, 36 to 85 y) and there was a male predilection of 2.7 to 1. The most frequently involved site was the skin of extremities, in 59.3% of patients, and 30 (81.1%) patients had advanced stage (III/IV) disease. Eleven (29.7%) patients presented with skin lesions as the first manifestation of MCL and 26 (70.3%) patients presented as relapse or progression of previously documented MCL and despite therapy for systemic MCL. Multiple skin lesions were more common (81.8%) in the former group whereas a solitary skin lesion was more frequent (65.4%) in the relapse/progression group (P=0.01). Thirty (81.1%) patients had skin nodules. Microscopically, the epidermis was spared with a grenz zone in all cases. A diffuse pattern of involvement was the most common architectural pattern (66.7%). In 27 (72.9%) patients, the MCL was either blastoid or pleomorphic variant, in 9 (24.3%) patients classic variant, and the disease was not further classified in 1 (2.7%) patient. The Ki-67 proliferation rate was higher in aggressive variants as compared with classic variant MCL (median 90% vs. 20%, P <0.01). In patients who presented skin lesions as a manifestation of disease relapse or progression, 16 patients initially had classic variant MCL and in 10 of the patients the MCL evolved over time (median interval: 4.1 y) to an aggressive variant at progression or relapse. The overall survival of patients with aggressive variant MCH was inferior to that of patients with classic variant MCL (median: 59 vs. 155.8 mo, P<0.05). In summary, MCL rarely involves the skin and correlates with relapse or progression of disease, aggressive morphologic features, and a poorer prognosis.