Well differentiated (benign) papillary mesothelioma of the tunica vaginalis.

An unusual mesothelial lesion occurred in the tunica vaginalis of the testis. It conformed histologically and immunohistochemically to well differentiated papillary mesothelioma of the peritoneum. Its aetiology remains uncertain, but this lesion, more than likely, is innocuous. It is important to recognise this entity, which is not well documented in the tunica vaginalis, because it may be misdiagnosed as a malignant mesothelioma and the patient may be subjected to unnecessary treatment.