Epididymal cyst

Epididymal cysts are the most common epididymal mass.

Epidemiology

Epididymal cysts have been reported in ~30% (range 20-40%) of asymptomatic individuals ⁵.

Pathology

They are usually of lymphatic origin ². The cysts contain clear serous fluid, lymphocytes, spermatozoa and debris.

Clinical presentation

Often manifests as a palpable mass. Approximately one-third of patients can be asymptomatic. It may be more prevalent in mountain bikers ³.

Radiographic features

They can be solitary or multiple with ~30% having more than one cyst ⁵.

Ultrasound

• cyst contents in uncomplicated cases are anechoic with no internal echoes
• posterior acoustic enhancement may be seen
• well-defined anechoic lesions
• larger cysts may contain septations
• larger cysts may displace the testis
  • this is a differentiating point from hydrocele which envelops the testis

Differential diagnosis

Imaging differential considerations include:

• spermatocele
  • usually has some internal echotexture, but may be indistinguishable from an epididymal cyst
  • epididymal cysts may arise throughout the epididymis, while spermatoceles almost always arise in the epididymal head ⁴
• tunica vaginalis cyst
• paratesticular abscess
  • will tend to show surrounding inflammatory changes
  • clinical context is different
• small hydrocele to be differentiated from large epididymal cyst with septations

See also

• paratesticular lesions