Abstract

Primary cutaneous spindle cell B-cell lymphoma is a rare unique variant of B-cell lymphoma that is generally associated with follicular center cell origin and demonstrates an excellent prognosis in contrast to primary cutaneous diffuse large B-cell lymphoma, although very few cases have been described in the literature. We report a case of 79-year-old-male with a history of multiple basal cell carcinomas of skin. He presented with a 3-month history of a progressive non-healing nodular erythematous lesion at his scalp. The biopsy showed a dense, diffuse to nodular dermal infiltrate, which involved the subcutis but clearly separated from the epidermis by a distinct Grenz zone; it was mainly composed of spindle cells with condensed chromatin and abundant abnormal mitosis. A minor cell population with centroblast-like or a large centrocyte-like morphology was also seen with admixed lymphocytes. Immunohistochemically, both spindle cells and centroblast/centrocyte-like cells were stained positive for CD20, Pax5, BCL-6 & CD30. CD10 and BCL-2 showed weak staining but negative for CD3, MUM1, CD1a and additional epithelial, melanocytic and vascular markers performed. The morphologic and immunophenotypic findings were consistent with a primary cutaneous B-cell lymphoma, spindle cell variant with a germinal center phenotype. Staging procedures, including a bone marrow biopsy showed no involvement. The patient underwent complete excision of the lymphoma with adjuvant radiation therapy. No recurrence is reported to date. This is a rare variant of primary cutaneous B-cell lymphoma that should be considered in the differential diagnosis of spindle cell lesions involving the skin.

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