spermatocele

Spermatoceles arise from cystic dilation of the epididymal ducts (usually the head/caput epididymis) or efferent ductules, resulting in retention of sperm and fluid within an epididymal segment. They are thought to result from obstruction or dilation of these small tubules, though exact etiology is often idiopathic; they are more common with advancing age. On physical exam, a spermatocele is felt as a distinct, freely mobile, non-tender, cystic nodule located above and posterior to the testicle, separate from the testis itself—this distinguishes it from testicular masses which should be considered malignant until proven otherwise. Transillumination is positive (fluid-filled), similar to a hydrocele, but a hydrocele surrounds the testicle diffusely while a spermatocele is a discrete mass attached to the epididymis. Scrotal ultrasound is the confirmatory diagnostic test, showing a well-circumscribed anechoic or complex cystic structure in the epididymis, sometimes containing internal echoes from sperm debris. Spermatoceles are typically asymptomatic and require no treatment unless large or symptomatic (causing discomfort or cosmetic concern), in which case surgical spermatocelectomy can be performed—though this carries a risk of epididymal injury and subsequent infertility, so it is generally avoided in men who desire future fertility. Clinically, spermatoceles must be differentiated from other scrotal masses: varicocele (soft, 'bag of worms', increases with Valsalva, does not transilluminate), hydrocele (transilluminates, surrounds testis), and testicular tumor (solid, does not transilluminate, associated with elevated tumor markers like AFP, hCG, LDH in germ cell tumors). This is a classic USMLE testable distinction in the scrotal mass differential diagnosis.