Post-traumatic cystic lesion following fracture of the radius.

Post-traumatic cystic lesions are an uncommon complication of fractures in children. They are benign, asymptomatic, non-expansive and tend to resolve spontaneously. Their cause seems to be the invasion of bone-marrow fat by subperiosteal hematoma, which may be visible on radiographs during fracture consolidation of the newly formed subperiosteal bone. The case we present is of cyst formation following a fracture of the distal radius and we evaluate the role of yellow bone marrow in the pathogenesis of the cyst. Its typical features clear differentiation from other lesions, preventing unnecessary and, possibly, invasive examinations.