Paratesticular Papillary Mesothelioma: A Case With Borderline Features

Abstract

Abstract Most often, mesotheliomas involve the serosal (serous) membranes of the pleura and peritoneum. Sometimes, mesothelial proliferations are identified in other locations. On very rare occasions, a mesothelioma is found within the tunica vaginalis of the paratesticular region. We report a case of papillary mesothelioma of the tunica vaginalis in a 52-year-old man. Although this lesion had papillary structures lined by a single layer of mesothelial cells with predominantly bland nuclear and cytologic features, there was evidence of a minimal presence of mesothelial cells in the underlying stroma. This combination of benign and semimalignant characteristics can make the diagnosis of such a lesion problematic. We think that a diagnosis of “borderline papillary mesothelioma” can be considered for similar mesothelial proliferations to allow for a possible increase in diagnostic accuracy and provide an enhanced informational platform from which patients and clinicians can benefit.