NCIt definition : A rare, indolent, usually solitary mesothelial neoplasm that arises from the tunica
vaginalis. It is characterized by the presence of a papillary architecture in which
the papillae are lined by cuboidal mesothelial cells. Mitotic figures are usually
absent. Stromal invasion is absent or minimal. It usually manifests with a hydrocele
and less frequently scrotal mass.;