We present the case of an 85-year-old man with a history of prostate adenocarcinoma treated with LHRH analogues, maintaining adequate biochemical control of the disease, who consulted for a picture of 2 months' evolution consisting of an enlarged left hemiscrotal, in the absence of pain, fever or other symptoms. Physical examination revealed a larger than normal left hemiscrotal, under tension, with a mass that prevented identification of the left testicle. Blood tests were requested, confirming beta-HCG and alpha-fetoprotein within the reference ranges, and scrotal ultrasound, reported as: "large cystic mass in the left scrotum, measuring 10x8.3 cm, compressing and displacing the testicle, compatible with a large cyst dependent on the epididymis, although other possibilities, such as cystadenoma, cannot be ruled out". Based on the clinical data, and assessing the differential diagnoses and the patient's situation, he was offered a bilateral orchiectomy, the right subalbuginea and the left inguinal, which he accepted.

The surgical specimen weighed 550 g, measured 11x11x9 cm and had a brownish-haemorrhagic colouring; when cut, a cystic cavity compressing the testicular parenchyma was evident. Microscopic pathological study, including sections of the cyst wall and the rest of the teste, revealed a cystic lesion lined with flat epithelium, with areas of ulceration, haemorrhage and necrotic tissue; the testicular parenchyma showed intense signs of atrophy, fibrosis and vascular congestion, with an almost total absence of germ cells in the seminiferous tubules.

The anatomopathological diagnosis was: benign testicular cyst compatible with cystic dilatation of the rete testis.