An 11-year-old boy came with a swelling over the right wrist since two years.
The swelling was painless and hard.
Frontal and lateral radiographs of the right wrist in an immature skeleton show an markedly expansile, lytic lesion with a 'black' matrix in the distal metaphysis of the radius. The zone of transition is narrow. The lesion has multiple septations and extensive cortical thinning. There is no periosteal reaction.