Presentation
Pain and swelling after ankle sprain, 4 days prior
Patient Data
A high-T2 signal lesion is visualized, posterior to the flexor hallucis longus tendon, inside the tarsal tunnel, representing a tarsal tunnel ganglion cyst. Another ganglion cyst is noted, deep to the peroneus brevis tendon, just posterolateral to sinus tarsi. Another small ganglion cyst is seen inside the sinus tarsi. A multiloculated intraosseous ganglion cyst is visible at mid-calcaneus, beneath the angle of Gissane.
On the coronal view, valgus deformity of the hindfoot is seen. Associated edema is noted at the soft tissue interposed between the calcaneus and fibula. Bone marrow edema is visible along with the posterosuperior aspect of the calcaneum. Findings are suggestive of lateral hindfoot impingement, with the calcaneofibular impingement likely responsible for the ganglion cyst formation adjacent to peroneus brevis, and talocalcaneal impingement responsible for the ganglion cyst formation beneath the angle of Gissane.
Abnormal signal is visualized at the anterior talofibular ligament, associated with a multiloculated ganglion cyst, representing an old ATFL injury.
Subchondral cystic change is noted along the anterior border of the tibial plafond.
Os trigonum and fluid collection in the retrocalcaneal bursa are visualized.
Case Discussion
This case represents multi-focal ganglion cysts, associated with the ankle.
Ganglion cysts are benign lesions, occurring in association with different musculoskeletal structures. They are known to occur as a result of mucoid degeneration of connective tissues, mainly in association with degenerative changes.
One typical location of intraosseous ganglion cysts is mid-calcaneus, beneath the angle of Gissane.
Most of the time, ganglion cysts are incidental findings; however, they may cause entrapment nephropathy, when located in specific sites, such as tarsal tunnel.
Lateral hindfoot impingement is a type of ankle impingement, that occurs more commonly as a consequence of posterior tibial tendon insufficiency. As this tendon elevates the talonavicular joint, its insufficiency will result in a flat foot and heel valgus deformity (pes planovalgus). Characteristic imaging findings are seen, with talocalcaneal impingement causing changes of calcaneum at the angle of Gissane and calcaneofibular impingement causing changes in the opposed surfaces of fibula and calcaneum.
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