Primary cutaneous mantle cell lymphoma of the leg with blastoid morphology and aberrant immunophenotype: a diagnostic challenge.

Mantle cell lymphoma rarely affects the skin and is usually a secondary involvement. The present case illustrates a primary cutaneous mantle cell lymphoma of the leg, with blastoid morphology and aberrant expression of CD10 and bcl-6, which was misinterpreted at the beginning as diffuse large B-cell lymphoma. A larger panel of immunohistochemical markers, including cyclin-D1, and molecular investigation showing the typical translocation (t11;14), pointed toward the correct diagnosis. Cutaneous diffuse B-cell lymphomas with unusual morphology should be interpreted cautiously, and the diagnosis made on the basis of an appropriate panel of antibodies and molecular studies.