抄録
Synovial osteochondromatosis, a benign condition of unknown origin, is characterized by multiple cartilaginous and osteocartilaginous nodules arising from metaplasia of the synovial tissue. The most common sites are the knee, the elbow, and the hip joint; it rarely occurs in the ankle or foot. We report a rare case of synovial osteochondromatosis in the retrocalcaneal Bursa.
A 31-year-old woman suffered from an insidious pain and swelling around the insertion of the right Achilles tendon for about two years. Gradually the hindfoot pain became severe, especially on weight bearing, and the swelling enlarged. Physical examination revealed a hard 1 cm mass with a smooth surface attached to the insertion of the Achilles tendon, There was marked tenderness over the mass, and the patient complained of pain of the hindfoot while she was walking. Routine radiographs of the right ankle were almost normal. A computed tomography scan revealed a f aintsof t tissue mass with a granular shadow at the anterolateral aspect of the Achilles tendon. A magnetic resonance image with T1-weighted sequences and T2-weighted sequences showed an image suggestive of multiple cartilaginous shadows with effusion in the retrocalcaneal Bursa. The mass was removed. There was an elastic, hard mass with a fibrous capsule situated at the anterolateral border of the right Achilles tendon, which was contiguous with the paratenon of the Achilles tendon. Several hard whitish fragments, like cartilaginous nodules, were connected by fibrous tissues. Histopathological examinations showed proliferative hyaline cartilages in the hypertrophied synovial bursa with fibrous degeneration. These findings were compatible with a diagnosis of synovial osteochondromatosis of the retrocalcaneal Bursa. Nine months after the operation, she was still free from symptoms. One should consider synovial osteochondromatosis of the retrocalcaneal Bursa as a differential diagnosis of hindfoot pain.
