Primary testicular lymphoma: a strictly homogeneous hematological disease?

Primary testicular lymphomas display mostly aggressive diffuse large cell B-cell lymphomas, which could be further subclassified into germinal center B-cell-like and an activated B-cell phenotype via immunohistochemistry. A retrospective analysis of primary testicular lymphomas diagnosed at the Institute of Pathology, Salzburger Landeskliniken (SALK) between January 1997 and December 2008 was done. Immunohistochemical staining and complete clinical data evaluation was carried out and linked to overall survival time. We found 18 cases of primary testicular lymphoma diagnosed in elderly patients showing no side predilection and having an aggressive clinical behavior with short overall survival independent of treatment. The lymphomas could for the most be classified into diffuse large cell B-cell lymphomas [15/18 (83.3%)] showing a non-significant prevalence of activated B cell phenotype [9/15 (60%)] compared to the germinal centre phenotype [6/15 (40%)]. Two of the cases were mantle cell lymphomas consisting of the infrequent pleomorphic subtype. The survival analysis revealed no significant difference for any of the investigated antigens. Primary testicular lymphomas are for the most DLBCL, but subtype classification reveal molecular heterogeneity inside this lymphoma entity. A distinction between those subtypes is necessary because of different clinical behavior and treatment.