15 years old right epididymis head 3mm cystic echo generally consider epididymal cyst. Epididymal cyst, also known as semen cyst, is a relatively common cystic disease in the scrotum, which occurs in young men, usually without special clinical symptoms, mostly due to the sensation of scrotal swelling and accompanied by slight pain and discovery. This disease is mostly caused by inflammation or obstruction of the ducts in the epididymis, resulting in blockage of the ducts, so that semen cannot be discharged smoothly and is retained in the epididymis. Since semen is trapped in the head of the epididymis, it may appear as cystic echoes on ultrasound; if the cyst does not interfere with normal life, no special treatment is usually needed; if the cyst grows or interferes with normal life, cystectomy may be performed. As the prognosis of this disease is good, if this symptom is found during physical examination, there is no need to worry too much, and it is recommended that the patient should consult a doctor in time, and under the guidance of a professional doctor, treatment and regular review can be done.