Ultrasound Presentation of Epithelioid Malignant Mesothelioma of the Tunica Vaginalis

Malignant mesothelioma of the tunica vaginalis (MMTV) is rare and accounts for less than 3% of all mesothelioma cases. Diagnosing MMTV is challenging because of its nonspecific clinical and radiological presentation. A 69-year-old male with no history of asbestos exposure, scrotal surgeries, or infections was initially suspected to have a large hydrocele on clinical examination. The ultrasound scan revealed turbid fluid with internal echoes and multiple hypoechoic, nodular adherent lesions in the tunica vaginalis. A subsequent MRI scan revealed a large complex encysted hydrocele with peripheral nodular opacities attached to the wall. Histopathology and immunohistochemistry confirmed a malignant epithelioid neoplasm that was positive for Pan-CK (AE1/3, calretinin, WT1, vimentin. CK5/6, CK7 and BerEP4), confirming the diagnosis of epithelioid MMTV. Consequently, MMTV should be suspected during scrotal ultrasound when multiple hypoechoic nodules accompanied by a chronic complex hydrocele are observed along the tunica vaginalis.