Plasmablastic lymphoma of the right testis

Abstract

Plasmablastic lymphoma (PBL) is a very rare disease. In 1997 Delecluse et al. reported a series of aggressive nonHodgkin’s lymphomas arising in the oral cavity of HIVpositive patients. In terms of clinical behavior, PBL is highly aggressive with short survival. This is the first report of PBL of the testis in Japan. A 76-year-old man had notable right-side scrotal swelling in September 2009 and underwent a medical examination in our hospital in October of the same year. Ultrasonographic examination demonstrated an enlarged right testis with a heterogeneous echo pattern. Levels of serum testicular tumor markers, including b-human chorionic gonadotrophin, a-fetoprotein and lactate dehydrogenase were all normal. We suspected that it might be a testicular tumor, so right high orchiectomy was performed in October 2009. Macroscopically, the tumor was ash gray in color, and there was no presence of bleeding or necrotic tissue (Fig. 1a). It consisted of diffusely proliferative, relatively uniform large cells with abundant cytoplasm. In particular, the tumor cells were plasmablastic-like and there were almost no mature plasma cells (Fig. 1b). Immunohistochemistry revealed the tumor cells to be positive for CD138, CD56 and epithelial membrane antigen; and negative for CD20, CD79a, CD3, CD10, CD30, cytokeratin and S100 protein. The pathological diagnosis was PBL. There was no evidence of human herpes virus-8 infection (according to polymerase chain reaction analysis), Epstein–Barr virus (according to in situ hybridization) and HIV. Pathologically, PBL is characterized by an immunoblastic or plasmablastic morphology and a plasma cell immunophenotype, and thus, its differentiation from other large B cell lymphomas or plasmablastic plasma cell neoplasms is often problematic. The immunophenotype of PBL tumor cells is almost identical to that of plasma cells; in particular, the expression of leukocyte common antigen and CD20 is absent or weak, but that of plasmacytic markers, such as CD138, is strongly positive. PBL has a well-established association with immunosuppression, and most particularly with HIV infection: approximately 80% of PBL patients are HIV-infected. Cases of PBL have also been reported after solid organ transplantation and in association with steroid therapy for autoimmune disease. PBL typically occurs in the oral cavity. However, PBL of the testis is very rare. Schichman et al. reported the first case. This report documents the third case of PBL of the testis in the world. Although cases of PBL have been reported from countries across the world , there has been only one report from Japan in the English-language published work. This may be because HIV infection is less prevalent in Japan than in other countries. The number of PBL cases in Japan may increase in the future.