Epididymal cyst

Last revised by Dr Jeremy Jones on 20 Sep 2021

Epididymal cysts are the most common epididymal mass.

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

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

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

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

  • 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

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

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3: with spermatic cord cyst
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