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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:
- 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
- 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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