Epididymal cyst

Last revised by Jeremy Jones on 6 Apr 2023

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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