200 Section - An Unusual Case of Intraneural Ganglion Cyst of the Cutaneous Branch of the Superficial Peroneal Nerve: A Case Report

This case report describes an intraneural ganglion cyst involving the cutaneous branch of the superficial peroneal nerve (SPN).

To our knowledge, no indexed reports describe isolated involvement of the cutaneous branch of the SPN.

Case Description:

A 28-year-old male presented with one-week history of right lateral ankle pain with electric-like radiation to the dorsum of the foot. He had a history of recurrent ankle inversion injuries with chronic right ankle sprain confirmed on musculoskeletal ultrasound (MSUS). Examination revealed a tender 3×3cm anterolateral distal leg mass, pain-limited inversion and eversion, and sensory deficit over the dorsum of the foot. MSUS and MR Neurography demonstrated a well-circumscribed cystic mass inseparable from the SPN. The patient underwent surgical excision with intraoperative neuromonitoring and histopathology, which confirmed the diagnosis. Postoperative rehabilitation focused on pain control, mobilization, sensory re-education, strengthening, and gait training, resulting in complete symptom resolution by seven weeks. At three months, symptoms recurred, with imaging suggesting possible recurrent ganglion cyst.

Discussions:

Pathology involving the cutaneous branch of the SPN may result in pain and paresthesia over the anterolateral leg and most of the dorsum of the foot, sparing the first interdigital space. Diagnostic evaluation involves the use of MRI and MSUS for visualization of peripheral nerve structures and identification of ganglion cysts. Although ganglion cysts may resolve spontaneously, surgical excision remains the gold standard due to lower recurrence rates compared with non-surgical management. There is no standardized postoperative rehabilitation protocol. Thus, management must be individualized.

Conclusions:

This case highlights the role of rehabilitation medicine in the diagnosis and postoperative recovery of a patient with an atypical ganglion cyst. It demonstrates ganglion cyst recurrence, even after surgical excision. The rarity of this case adds insight to the limited existing literature, raises awareness of uncommon presentations of ganglion cysts, and may help guide future clinical decision-making.