Epineural Ganglion Cyst of the Sural Nerve at the Foot: A Case Report

Purpose: Ganglion cysts of peripheral nerve are uncommon. Ganglion cysts located within the nerve and extraneural ganglia that cause symptomatic nerve compression have been reported. We report an unusual case of epineural ganglion cyst confined to the epineurium of the sural nerve at the foot. Methods: A 45-year-old woman was referred because of a mass on the foot. She had six months' history of pain and numbness in the right small toe. During the examination of the lesion, multinodular cystic mass was identified arising from the epineurium of the sural nerve. The nerve fascicles were compressed by the cyst, but the cyst wall clearly did not invade the fascicle. With the aid of surgical microscope, the epineural cyst was completely excised along with epineural tissue to which it was attached, and the sural nerve was decompressed. There was no relationship between the cyst and either the joint capsule or tendon sheath. Since the cyst was on the periphery of the nerve it was possible to remove the cyst intact without damaging the underlying fascicles. Results: The postoperative course was uneventful. Pathologic examination showed a ganglion cyst with a degenerated collagen fibers and contained a yellowish, jelly-like mucinous substance. No neural elements were identified within the cystic wall. Her sensory impairment improved progressively. At the 15 months follow-up, she was asymptomatic with no neurological deficits. Conclusion: Rarely, ganglion cysts can involve peripheral nerves, leading to varing degrees of neurological deficits. Intraneural intrafascicular ganglion may be difficult to separate from the neural elements without nerve injury. Epineural ganglion, subcategorized as intraneural extrafascicular ganglion, can be removed without damage to the underlying nerve.

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