Clapper, Patti, Schweizer and Mason

The most common types of mesothelioma that one reads about and is more often diagnosed are pleural, pericardial, and peritoneal.  There is another type, even rarer than the other three, called tunica vaginalis mesothelioma.  There are very few cases of this type of malignant mesothelioma reported and diagnosis usually doesn’t occur until discovered during surgery.

Exposure to asbestos is believed to be the main causative factor, and most patients are adults or elderly. As with other types of mesothelioma, tumors are formed in the mesothelium lining of the tunica vaginalis.  The tunica vaginalis forms when the outer portion of the processus vaginalis closes during embryonic development.  The features and understanding of this type of mesothelioma is very limited due to its rarity.  Radical inguinal orchiectomy (removal of one or both of the testicles) is one of the recommended modes of treatment.

Paratesticular mesothelioma is a type that arises out of the tunica vaginalis.  A recent study from the Oncology Department at Johns Hopkins Hospital compared data of paratesticular mesothelioma with cases of tunica vaginalis mesothelioma in an attempt to better understand the differences in prognostic and immunohistochemical features of these malignant lesions. 

Researchers discovered that these types of lesions behaved more benignly and prognosis with one patient was as long as nine years.  Median survival rates of other types of mesothelioma are less than a year, and a five year survival rate is extremely rare.  Therefore, this study raises questions about the nature of this type of cancer, which are more complex yet less histologically malignant than other mesotheliomas.  More investigation will need to be done to make definitive conclusions; yet such research is hampered due to the lack of cases available to study.