Intratendinous ganglion cyst of the semimembranosus tendon

Abstract

Intratendinous ganglion cyst is a very rare lesion with an unknown aetiology that originates within the tendon. We encountered a case of 43-year-old woman who complained of a palpable, non-tender mass in the thigh with increasing swelling. An intratendinous ganglion cyst in the semimembranosus tendon of the lower extremity was diagnosed and located by ultrasound and MRI. Nine months after a surgical excision, there were recurrent ganglion cysts along the semimembranosus tendon. We describe this case with a review of the relevant literature.

Figure 1

Ultrasonography of the right posterior thigh shows a large (10 × 1.7 cm) tubular well-circumscribed intramuscular anechoic mass with tapering of the distal end. This lesion has an internal thin echogenic ridge.

Figure 2

(a) Axial T₁ weighted spin-echo image (repetition time (TR)/echo time (TE), 722/20) shows an isointense mass in relation to the signal intensity of skeletal muscle in the semimembranosus tendinous portion (arrow) at the level of the right distal posterior thigh. (b) Sagittal T₂ weighted fat-suppressed fast spin-echo image (TR/TE, 3000/99) shows a high signal intensity elongated tubular cystic mass-like lesion in the semimembranosus tendinous portion (13 cm in craniocaudal direction). (c) Gadolinium-enhanced coronal T₁ weighted fat-suppressed (TR/TE, 900/12) scan shows a thin peripheral rim-enhancing lesion within the semimembranosus tendon (arrow).

Figure 3

Nine months after surgery, the follow-up CT scan of the right thigh with enhancement (sagittal reformation) shows a thin tubular (arrowhead) and another larger (arrow, 2.8 × 1.9 × 2.8 cm) ovoid cystic mass with peripheral rim enhancement along the right semimembranosus tendon. These lesions are probably recurrent ganglion cysts due to post-operative leakage and partial resection.