Primary cutaneous T-cell-rich B-cell lymphoma. A case report with a 13-year follow-up.

Cutaneous B-cell lymphomas constitute approximately 20% of primary cutaneous lymphomas. Most histologic subtypes of nodal B-cell lymphomas also occur primarily in the skin. The recently described T-cell-rich B-cell lymphomas (TCRBCLs) manifest mainly in the lymph nodes. This article presents a case of TCRBCL arising primarily in the skin, the origin of which could be traced back 13 years. The patient is a 59-year-old man. Plaque-like and nodular skin infiltrates had first appeared in the left preauricular region. Repeated examinations never found any extracutaneous involvement. A skin biopsy and a retrospectively studied 10-year-old skin specimen showed identical histologic features. Immunohistochemistry identified the TCRBCL previously considered as cutaneous Hodgkin's disease or a diffuse centroblastic centrocytic non-Hodgkin's lymphoma. A clonal B-cell population was detected by polymerase chain reaction, showing a rearrangement of IgH gene. The case of this patient shows that primary cutaneous TCRBCLs, similarly to other B-cell lymphomas in the skin, may have a good prognosis, in contrast to their nodal counterparts.