Scrotal hematocele is defined as retention of blood in the tunica vaginalis. Although it is usually an acute change, it can also have a chronic course. A 55-year-old man was being treated for hypertension and diabetes in the Department of Internal Medicine at our hospital. He visited the hospital’s Department of Urology because 3 months earlier he had noticed enlargement of the right scrotum without trauma to the perineum. The right scrotum was swollen to the size of a small child’s head. Imaging examination showed no testicular tumor. Puncture yielded 550 ml of bloody fluid. Surgery was performed to find and treat the source of bleeding. The tunica vaginalis was highly irregular and thickened. Considering the possibility of mesothelioma or other malignancy, we removed the testis after transection of the spermatic cord as proximally as possible. The histopathological diagnosis was encapsulated hematoma with cholesterin granuloma, which was diagnosed as chronic scrotal hematocele.

Small cell carcinoma of the prostate is a rare, highly malignant disease with a poor prognosis that often presents with metastatic lesions at the time of diagnosis. A previous study reported that neuroendocrine differentiation occurred during hormonal therapy for prostate cancer and progressed to small cell carcinoma. We encountered one case in which small cell carcinoma was diagnosed at the first visit and another case involving possible neuroendocrine differentiation.