Mesothelioma subtypes of the tunica vaginalis: a rare case report and review of histological criteria.

Well-differentiated papillary mesothelioma (WDPM) is a rare histological subtype of mesothelioma arising from the tunica vaginalis. We present a case of a 23-year-old male with a palpable para-testicular lump of 3 years duration. Scrotal exploration revealed a grossly abnormal cystic appearance of his tunica vaginalis. An excision biopsy confirmed WDPM of the tunica vaginalis. The three subtypes of mesothelial tumours of the tunica vaginalis are described by their distinct histological features, tumour growth and reported prognosis. A summary of immunohistochemistry and the surgical management across the disease spectrum is provided. Recent clarification of the histological criteria of WDPM provides the opportunity for surgeons to offer a limited approach to managing this indolent tumour that mimics malignant mesothelioma. However, the lack of evidence on recurrence and progression rates in WDPM restricts most surgeons to performing a radical orchidectomy, as was performed in this case.