Abstract: Introduction: Extra Skeletal Chondroma (ESC) is a benign, slow-growing cartilaginous tumour arising from tenosynovial sheaths. The aim of this article is to report and discuss a case of ESC affecting Ring finger flexor tendon Sheath, rare presentation. A 11-year-old female presented with a swelling in the volar aspect a of the right middle finger flexor tendon sheath. On clinical examination, there was a 4cm/ 1cm non-tender, hard, ill-deï¬ned mass. Ultrasound showed a large well deï¬ned thick wall mass, located inside flexor tendon sheath. Magnetic Resonance Imaging showed a large well deï¬ned mass involving the flexor tendon sheath of Ring finger. The patient underwent wide local excision under regional block. The histopathological examination of the specimen revealed binucleated chondrocytes with dots of calciï¬cation conï¬rming Extra Skeletal Chondroma.
Discussion: There are many theories trying to explain the origin of ESC, as some authors think that it originates from the pluripotent cells of the tenosynovium, while others state that it may be derived from metaplasia of the tendon sheath. In this case, the lesion was completely surrounded by ï¬bers away from the nearby tendons sheath, and periosteum.
Conclusion: Extra skeletal chondroma is a rare benign lesion, although mostly affect the upper extremities, it can be found anywhere in the body, histopathological examination of the specimen is the diagnostic method of choice.
