Spermatocele

Spermatoceles are a common type of extra-testicular cyst, and represents cystic dilatation of tubules of the efferent ductules in the head of the epididymis.

Clinical presentation

Usually a painless, incidental finding but can present as a mass lesion if large ³.

Pathology

Spermatoceles are usually unilocular but can be multilocular and may be associated with a prior vasectomy. They are more common than epididymal cysts, but can appear very similar. 

Aetiology

The exact cause of spermatoceles remain unclear but is thought to be due to blockage of the epididymal ducts with proximal dilatation. This may be idiopathic or secondary to an infectious or inflammatory process ³. 

Radiographic features

Ultrasound

At sonographic examination, spermatoceles are well-defined epididymal hypoechoic lesions usually measuring 1-2 cm and demonstrating posterior acoustic enhancement. They are usually irregular, with fine low-level internal echoes and sometimes septations.

Differential diagnosis

General imaging differential considerations include:

• epididymal cyst
  • unlike epididymal cysts, spermatoceles often contain low-level echogenic proteinaceous fluid and spermatozoa
  • spermatoceles can be septate
  • they can however be anechoic and thus indistinguishable from epididymal cysts
• ectasia of rete testes: intratesticular spermatocele communicates with the seminiferous tubules, however ectatic rete testes do not communicate directly
• intratesticular simple cyst: simple cysts are usually smooth walled-walled and anechoic, while spermatocoelesspermatoceles show irregular wall with low level-level echoes

See also

• paratesticular lesions