Primary testicular diffuse large B-cell lymphoma (PT-DLBCL) represents a rare and aggressive extranodal non-Hodgkin's lymphoma (NHL) with some specific features that differ from other NHLs. Formalin fixed, paraffin wax embedded (FFPE) samples of 21 PT-DLBCLs and 30 comparative patients with DLBCL were analysed. All PT-DLBCL patients were treated with rituximab-containing regimens, intrathecal prophylaxis (10 patients), and irradiation of the contralateral testis (9 patients). FFPE samples were additionally analysed by immunohistochemistry (Bcl-2, c-Myc protein expression) and fluorescence in situ hybridisation (FISH) (BCL2 and MYC). The patients with PT-DLBCL (median age 48.5 years), had low frequency of B symptoms (28.6%) and were often diagnosed in I and II Ann Arbor clinical stage (66.0%). The majority of PT-DLBCL (80.9%) had a non-germinal centre B-cell-like immunophenotype. Immunohistochemical staining showed increased c-Myc protein expression in the PT-DLBCL group compared to the control group (p = 0.016). MYC rearrangement was detected in 1 of 14 (7.0%), and MYC amplification in 3 of 14 (21.0%) patients. One of the 14 cases (7.0%) in the PT DLBCL group showed BCL2 rearrangement, and four of 14 (28.05%) cases showed BCL2 amplification. Complete remission (CR) was achieved in 75.0% of PT-DLBCL patients who had superior survival compared to those who did not achieve CR (median 48 vs. 21 months, p = 0.012). Patients with PT-DLBCL express some immunohistochemical, biological, and clinical features that might differentiate them from nodal and extranodal DLBCL patients, indicating the need for a more personalised treatment approach.
Keywords: diffuse large B cell lymphoma; primary testicular lymphoma.