Testicular lymphoma--a retrospective, population-based, clinical and immunohistochemical study.

From a population-based registry, 35 patients with histologically verified testicular lymphomas were identified: diffuse large B-cell lymphomas (DLBCL) in 33 and peripheral T-cell lymphomas in two cases. Twenty-two patients had localized disease (Pe stage I and II). Twenty-eight patients received systemic chemotherapy, 17 of whom also received intrathecal prophylaxis, and 12 out of these 17 also received radiotherapy to the contralateral testis. In the Pe stage I/II group, 7 out of 21 patients in complete remission (CR) relapsed. In 5 of them the CNS was involved (isolated CNS relapse in three). Remarkably late relapses occurred (up to 127 months). Intrathecal prophylaxis seemed to reduce the frequency of relapses involving the CNS, but the relatively short follow-up (median 45 months, range 34-88, for censored patients) prevents firm conclusions regarding efficacy. The outcome for the stage IV patients was poor, with only 1 out of 11 patients in continuous CR. Immunohistochemical analysis of the DLBCL tumours revealed that 31% had the germinal centre B-cell-like phenotype. CD44 was expressed in all the tumours of stage IV patients but in less than half of the Pe stage I/II patients. A high intratumoural microvessel density was correlated with a high degree of Ki-67 positive tumour cells and an inferior overall survival.