Malignant mesotheliomas of the tunica vaginalis are extremely rare tumors, especially in young patients. We report a case of a 15-year old patient presenting with clinical signs of hydrocele. Preoperative ultrasound scanning revealed two papillary lesions. Initially, before mesothelioma was suspected, the patient was submitted to focal resection of the macroscopic lesions. Following diagnosis by histopathology, the patient was submitted to radical orchiectomy and hemiscrotectomy. The patient presents no signs of local or systemic recurrence at the time of writing. A review of the literature on the subject has been included.