Painful Snapping of Thumb Caused by Osteochondroma of Trapezium.

Osteochondroma is the most common benign bone tumor. Lesions occurring at the carpal bones are extremely rare. There are very few cases of osteochondroma at the trapezium had been reported in the English literature. We reported a 47-year-old patient with an osteochondroma of the left trapezium presented with painful snapping of abductor pollicis longus tendon.