Extranodal CD20-positive peripheral T-cell lymphoma presenting with adrenal and testicular masses.

We report a case of extranodal CD20-positive peripheral T-cell lymphoma (PTCL). A 59-year-old man was admitted because of a right testicular mass in April 2006. CT scan revealed bilateral adrenal masses and he underwent right orchiectomy. The enlarged testis showed diffuse infiltration of large CD20-positive lymphocytes with slight CD3-positive cells. These cells were negative for CD10 and showed a high MIB-1 index. The pathological diagnosis was diffuse large B-cell lymphoma. He received R-CHOP, but developed brain involvement. He received whole brain radiotherapy following high-dose methotrexate, but he died of disease progression in August 2007. At autopsy, lymphoma cells were definitely positive for CD3 and negative for CD20. Monoclonal TCR gamma gene rearrangement was detected in the brain specimen without IgH rearrangement by PCR. The testicular tumor also showed the same clonal bands. Immunohistochemical re-evaluation of the testis showed CD20+, CD79a-, PAX5-, MUM1-, CD3 p+, CD5 p+, CD4-, CD8-, CD7 p+, granzyme B+, and TIA1+. Based on the clinical course and immunohistology, we finally diagnosed this case as extranodal PTCL-nos (not otherwise specified) with aberrant CD20 expression, which is extremely rare. The detection of gene rearrangement, plural immunohistochemical markers and knowledge of the possibility of CD20+ PTCL-nos are necessary for such cases.