Report of a Rare Case of Primary Malignant Mesothelioma of the Perineum Presenting as a Scrotal Abscess

A 57-year-old man presented with erythema and pain in the scrotum for 1 week, with pus exuding from the ruptured scrotum for 1 day. Physical examination showed an enlarged left scrotum, with a small area of ruptured skin, and yellowish-white discharge from the rupture was visible in the lower posterior part of the testes near the perineum, with slightly high local skin temperature, tenderness, and fluctuating sensation. The initial reproductive system ultrasound and pelvic CT were suggestive of inflammatory infection, which was confirmed by histology following two surgeries. The patient's condition did not show improvement for a long period of time, and repeat pelvic CT suggested multiple enlarged inguinal lymph nodes. Fine needle aspiration cytology suggested metastatic cancer. Histopathological examination and immunohistochemistry of the perineal scrotal area showed malignant mesothelioma, and whole-body PET-CT suggested pulmonary metastases and invasion into the surrounding tissues, such as the organs of the reproductive system. The patient received chemotherapy and immunotherapy, but the disease progressed rapidly, and he ultimately died of respiratory failure.