Malignant mesothelioma of the tunica vaginalis.

Introduction: Malignant mesothelioma involving the tunica vaginalis is an extremely rare tumor.

Case: We describe a case of a 39-year-old man who initially presented with discomfort in the left testis and underwent resection of a hydrocele in the left testis. A pathology examination of a frozen section of a lesion on the tunica identified the lesion as mesothelioma, which was confirmed by a second pathology examination. No metastatic disease was found. The patient subsequently underwent a left radical orchiectomy and a partial scrotectomy, and has been disease free for 7 years.

Discussion: The first case of malignant mesothelioma involving the tunica vaginalis, a structure embryologically derived from a layer of reflected peritoneum known as the "processus vaginalis," was reported in 1957. Only 73 cases were reported in the literature between 1966 and 1997. In up to 41% of cases, there is a positive history of asbestos exposure. Young age and localized disease are associated with a better prognosis. Radical orchiectomy limits recurrence, which usually occurs within 2 years, but may occur up to 15 years after surgery.