Regression of an ossifying fibroma of the tibia after a fracture involving the lesion. Possible role of the periostina.

Ossifying fibroma (OF) of the long bones is a benign fibro-osseous lesion typically seen in the first decade of life. OF usually progresses until the age of 10 years, but is occasionally found to regress spontaneously after puberty. The pathogenesis of OF is unknown; however, it has been suggested that the basic defect is in the periosteum. We present the radiological course of an OF of the tibia in a young patient, showing a rapid almost complete regression of the lesion after a tibial fracture at the lesion site. We postulate that the fracture-induced activation of the periosteum in a growing skeleton was fundamental to the regression of the lesion.