Imaging of mesothelioma of tunica vaginalis testis

Objectives: To describe the imaging findings in a series of patients with mesothelioma of the tunica vaginalis testis. Methods: We reviewed clinical data, imaging findings and follow-up information in a series of 10 pathology-proven cases of mesothelioma (all had US; 2 had MR) of the tunica vaginalis. Results: A variety of patterns could be observed, the most common (5/10) being a hydrocele with parietal, solid and hypervascular vegetations; one patient had a septated hydrocele with hypervascular walls; one had multiple, solid nodules surrounded by a small, physiological quantity of fluid; one a cystic lesion with thick walls and vegetations compressing the testis; two had a solid paratesticular mass. MR showed multiple small nodules on the surface of the tunica vaginalis in one case and diffuse thickening and vegetations in the other one; lesions had low signal intensity on T2-w images and were hypervascular after contrast injection. Conclusions: A preoperative diagnosis of mesotheliomas presenting as solid paratesticular masses seems very difficult with imaging. On the contrary, the diagnosis must be considered in patients in whom a hydrocele with parietal vegetations is detected, especially if these show high vascularity. Key Points: • Mesotheliomas of the tunica vaginalis are rare, often challenging to diagnose preoperatively. • Most common finding is a complex hydrocele with hypervascular parietal vegetations. • Septated hydrocele, nodules without hydrocele, a thick-walled paratesticular cyst are less common. • Preoperative diagnosis may allow aggressive surgical approach and, possibly, a better prognosis.