Intravascular B-cell lymphoma: the role of skin biopsy.

Intravascular B-cell lymphoma is a rare aggressive systemic neoplasm with cutaneous and neurological presentations, which commonly eludes the diagnosis ante mortem. First reported in 1959 as "angioendotheliomatosis proliferans" by Pfleger and Tappeiner, it is a subtype of extranodal diffuse large-B-cell lymphoma defined by an intravascular proliferation of clonal lymphocytes. We describe a case of intravascular lymphoma in a 68-year-old female who presented with altered mental status and indurated, erythematous, ecchymotic plaques with overlying telangiectasia and ulceration. The diagnosis was made by skin biopsy of an abdominal plaque revealing large hyperchromatic cells filling the lumina of several small blood vessels within the dermis and subcutis. CD20 and CD79a immunostains were strongly positive, confirming the diagnosis of intravascular large-B-cell lymphoma. On review of a previous biopsy from another institution, which was reported to be nondiagnostic, we were able to find tumor cells in the blood vessels but only very focally. The presence of a brisk, perivascular, nonneoplastic lymphocytic infiltrate may have obscured the identification of tumor cells. This case illustrates an unusual subtype of extranodal diffuse large-B-cell lymphoma, which demonstrates protean clinical presentations, requires microscopic examination for diagnosis, but can be easily overlooked on skin biopsy.