A male patient who presents with the complaint of a “swollen” scrotum is found t

1 -- A hydrocele, which is the most common cause of scrotal swelling, is a collection of fluid within the tunica vaginalis. A hydrocele may be differentiated from a solid mass by transillumination or ultrasound of the scrotum. A spermatocele is a mobile, usually painless mass that forms when efferent ducts in the epididymis dilate and form a cyst. A varicocele is an abnormal dilation of a vein within the spermatic cord. It is caused by incompetent or congenitally missing valves that allow blood to pool in the spermatic cord veins. The dilated vein forms a soft mass that may be painful. Scrotal cancer would be manifested by a solid mass rather than a fluid-filled area.