Malignant mesothelioma of the tunica vaginalis testis: A case report and literature review.

Malignant mesothelioma of the tunica vaginalis testis is an extremely rare tumor without specific clinical manifestations, mainly including hydrocele formation and a painless mass. We herein present the case of a patient with hydrocele of the left testis, without any other complaints. Tunica vaginalis subinvolution was performed, and postoperative pathological examination revealed a malignant mesothelioma arising from the left tunica vaginalis testis. Whole-body positron emission tomography-computed tomography (PET-CT) and subsequent abdominal and pelvic magnetic resonance imaging (MRI) revealed no evidence of local lymphadenopathy. Radical left orchiectomy was performed after the pathological diagnosis. The pathological examination after the second surgery demonstrated that the tumor had invaded the adjacent periorchium and spermatic cord, but there was no evidence of local lymph node metastasis. Pemetrexed and cisplatin were administered at a dose of 900 and 130 mg, respectively, on the first day of a 28-day cycle. After 6 months of therapy, the disease had not progressed on abdominal and pelvic PET-CT and MRI. The patient was still followed up in our urology outpatient clinic at the time of the present report. Although testicular hydrocele is a common and easily diagnosed condition, detailed medical history and physical examination are required. Thus, when clinicians encounter patients with testicular hydrocele, a variety of possible causes must be considered, including testicular or paratesticular tumors, even rare tumors such as mesothelioma of the tunica vaginalis testis.