Cutaneous Involvement by Mantle Cell Lymphoma: Expanding the Spectrum of Histopathologic Findings in a Series of 9 Cases.

Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm with cutaneous involvement in ∼1% of cases. We present a single institutional series of nine patients (12 specimens) with cutaneous involvement by systemic MCL and review the clinicopathologic features. Six males and 3 females (age range 55-87 years) were included. Sites of involvement were head and neck (n = 3), trunk (n = 5), and extremities (n = 4). Histopathologically, 3 showed classic cytomorphology, 2 were blastoid, 3 pleomorphic, and 1 showed features resembling marginal zone lymphoma. Two cases presented with cutaneous lesions as the first tissue manifestation of the disease. A second malignancy was identified in 3/9 cases (2 melanomas and 1 papillary thyroid carcinoma). In one patient, MCL was juxtaposed with metastatic melanoma within the same biopsy specimen. Fluorescence in situ hybridization studies, when available, demonstrated the characteristic t(11,14) translocation. Direct immunofluorescence was performed on one case and showed immunoglobulin M (IgM) expression on the tumor cells. Follow-up was available in 7 cases (mean 42 months, range 6-78 months) and revealed death from disease for 6 patients that occurred within 1 week to 11 months (mean 4 months) after cutaneous involvement. In our series, 6/9 cases demonstrated blastoid, pleomorphic, or marginal zone lymphoma-like morphologies that could potentially mimic other hematolymphoid neoplasms. MCL may show surface IgM expression on DIF or may occur in association with other solid tumors. Immunohistochemistry for cyclin D1 and/or SOX-11 may be helpful for diagnosis, and imaging studies may be necessary to detect systemic involvement when cutaneous involvement is the first manifestation of the disease.