Mesothelioma of the tunica vaginalis testis.

Malignant mesothelioma arising from the serosal membranes of the tunica vaginalis testis (TVT) is rare. Most examples in the published medical literature are individual case reports. This study presents the clinicopathologic findings of mesothelioma of the TVT in one of the largest series to date. Design Individuals with mesothelioma of the TVT were identified from a database of more than 4000 mesothelioma cases and their clinicopathologic features were recorded. Eighteen men with malignant mesothelioma (MM) and two with well-differentiated papillary mesothelioma (WDPM) of the TVT were identified, which represented 0.6% of males with mesothelioma in study population. The median age at diagnosis was 72years (range, 32-85years). A neoplasm was not suspected preoperatively in 12 of the 17 (71%) men whose clinical presentation was known, seven of whom presented with hydrocele and five with inguinal hernia. The other five had a clinically recognized mass. Seven of the men underwent herniorrhapy, seven radical orchiectomy, three hydrocelectomy, and three paratesticular mass biopsy or excision as the initial diagnostic procedure. Twelve of the MM cases were epithelioid and six were biphasic. Among the six men with MM who had ≥6months follow-up, one was alive with no evidence of disease at six months and five were known to have died of disease 8-74months (median=31.5months) following diagnosis. Three men with MM had received either chemotherapy or radiation therapy. Of the two men initially diagnosed with WDPM, one was alive without evidence of disease five years after diagnosis, while the other had findings more compatible with MM with peritoneal involvement two years following initial diagnosis. In 15 of the 18 cases of MM (83%), there was documented occupational or paraoccupational exposure to asbestos, the average duration of which was 33years (range, 2-46years). Information regarding the presence or absence of pleural plaques was available in 5 of the MM cases and pleural plaques had been found in four. Lung tissue was not available for fiber analysis in any of the cases. One additional case originally diagnosed at another institution as MM of the TVT was reclassified as adenocarcinoma following performance of additional immunohistochemical testing. TVT is a rare site of MM, the diagnosis of which is often unsuspected preoperatively. Like its counterparts at other serosal sites, MM of the TVT is an aggressive tumor with a poor prognosis that evidence would suggest is etiologically associated with asbestos in at least some cases.