Cutaneous diffuse large B-cell lymphoma, leg type, secondary to testicular diffuse large B-cell lymphoma

Abstract

Conflict of interest: none declared. Diffuse large B‐cell lymphoma (DLBCL) is the most common testicular lymphoma in adults. It usually occurs in men older than 60 years, and is an aggressive tumour with intermediate prognosis. Testicular DLBCL can disseminate to diverse extranodal sites, with the skin being a rarely affected site.1 2 An 80‐year‐old man presented with 1‐month history of multiple infiltrated violaceous nodules on his left leg (Fig. 1). He had previously been diagnosed as having a testicular DLBCL, and had been treated with orchidectomy, four courses of chemotherapy with R‐CHOP (rituximab, cyclophosphamide, doxorubicin and prednisone), prophylactic central nervous system chemotherapy, and radiotherapy to the testis and ipsilateral inguinal lymph nodes, which had resulted in complete response. The cutaneous tumours had first appeared 2 years after resolution. On histological examination of a skin biopsy, a diffuse dermal infiltration of atypical large lymphocytic cells was seen, composed mostly of immunoblasts and centroblasts (Fig. 2). Immunohistochemical markers were positive for CD20, CD45, Bcl‐2 and MUM1, and negative for Bcl‐6, CD3 and CD10. The same features were found in sections from the previous testicular lymphoma when these were re‐examined. Molecular analysis identified monoclonal rearrangement of the immunoglobulin heavy chain gene by the same clone in testis and skin.