Posttraumatic cyst-like lesions of cortical bone in children.

Cyst-like cortical defects appearing after minor greenstick fractures in children have occasionally been described. These lesions are asymptomatic and appear just proximal to the fracture line within the area of subperiostal new bone formation. Although the pathogenesis of these lesions remains conjectural, complete resolution occurs, without adverse effect on fracture healing. Only a few cases of these posttraumatic cysts have been previously reported, mainly in radiological literature. We present a case of cyst formation after a greenstick fracture of the distal radius. We discuss the evolution of these post fracture cysts and review the current theories on their pathogenesis.