Tenosynovitis of the peroneal tendons due to hypertrophic peroneal tubercle
Imaging Findings:
 • Large volume ofT2-hyperintense fluid signal within the tendon sheath of the peroneal tendons.
 • Marked marrow edema of the calcaneus with a hypertrophic peroneal tubercle and vertical non-displaced fracture of the tubercle on the Coronal PD fat saturated sequence.
 • The thickened peroneus brevis lies superior and the peroneus longus inferior to the peroneal tubercle.
Case description:
 • Enlarged peroneal tubercle can impinge the peroneal tendons and result in stenosis tenosynovitis due to chronic friction and increased tension on the tendons.
     - Thickened tendons with fluid-signal in the sheath.
 • Can result in bone marrow edema of the calcaneus at the tubercle.
 +/- adventitial bursitis adjacent to the peroneal tubercle.
 +/- thickening of the inferior peroneal retinaculum.
Differential diagnosis for similar location of pain:
 • Peroneal tendon subluxation/dislocation or tear.
 • Talar osteochondral lesions.
 • Calcaneal stress fracture.

Dr. Donald von Borstel @DrvonBorstel

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