Malignant Mesothelioma of the Tunica Vaginalis Testis. A Clinicopathologic Analysis of Two Cases with a Review of the Literature.

Paratesticular malignant mesothelioma is an extremely rare type of mesothelioma with only a limited number of reported cases. Its clinical differentiation is challenging, and its diagnosis is almost exclusively accidental. The major risk factor is exposure to asbestos, typically with a long latency between exposure and diagnosis. The current study presents the clinical data of two patients diagnosed with paratesticular malignant mesothelioma. We evaluated a large spectrum of risk factors in the patients histories. The histomorphological and immunohistochemical characteristics were analysed and put into the perspective of a broad differential diagnosis. Both cases of malignant epithelial mesothelioma of the tunica vaginalis testis clinically presented as unilateral hydroceles. Patients underwent surgery with the perioperative finding of a tumour. Radical inguinal orchiectomy was the treatment of choice for both patients. After comprehensive staging, the second patient underwent a second step of inguinal and pelvic lymph node dis- section. Follow-up visits revealed recurrence of the disease in the first patient. Resection of the tumour was performed. The histology confirmed the relapse of a tumour with identical features to those of the first tumour. Chemotherapy and radiotherapy were not indicated. Both patients are currently in complete remission. In conclusion, surgical treatment had a determinative role in the prognosis of these patients. Radical orchiectomy is the treatment of choice for localized disease. Lymph node dissection can be considered in the case of lymph node enlargement. There is a lack of evidence-based data for adjuvant chemotherapy and radiotherapy. Patients should be referred to experienced multidisciplinary cancer centres for a second opinion on histology, treatment, and a follow-up plan.Key words: mesothelioma - tunica vaginalis testis - hydrocele - asbestos exposure.