[Osteioid osteoma of the thumb: sub-periostal localization]

The case of a 19 year old man with a painful and swollen thumb is reported.Xrays showed a thickening of the cortex of the phalanx, and CT scan led to the diagnosis of osteoid osteoma, showing a typical aspect of a nidus.Pain stopped immediatly after surgical procedure, and the volume of the thumb became normal after 3 monthes.While the hand is not a frequent location for osteoid osteoma, the thumb, especially in the periostal region, is very rare.Contrary to the medullary spongy bone location, Xrays signs are modest, and the CT scan is of great value in diagnosis and specifies the localization.