[Epidermoid cyst of the testis. A case of difficult preoperative diagnosis].

Epidermoid cysts os the testes have an incidence between 1-2% of total tumours in that organ. The embryonary origin of this benign neoplasia is unknown, although the most widely accepted theory is they are monodermal teratomas. Differential diagnosis with germinal cells is established through the characteristic dartboard-like ultrasound image, which allows testicular conservant surgery though only in the case of certainty about the lesion. Since that was not the case and given the ultrasound variability recorded in the literature, radical orchiectomy was performed to overcome the persistent doubt at staging the tumour's benignancy.