Tumour-like lesions in the femur with cementum-like material. Does a "cementoma" of long bone exist?

Five hundred and seventy nine juvenile bone cysts were analysed to evaluate the radiological and histological structures. Most of the juvenile bone cysts showed a typical appearance radiographically; histologically they had a cyst wall consisting of fibrous tissue without an epithelial lining. In many of these lesions newly formed bone trabeculae, granulation tissue, calcium deposits, and in some cases focal deposits of a homogeneous material resembling cementum of tooth were observed. In 28 lesions a well circumscribed, round focus was observed within the proximal femur or femoral neck radiologically, showing dense calcification with a small central radiolucency. In some cases, the intraosseous focus was almost solid without a cystic appearance. Histologically the unusual bone lesions consisted almost exclusively of calcified cementum devoid of cells. Lesions of this type were found exclusively in the proximal femur of patients between 47 and 56 years of age. Because of the radiological and histological appearance we would like to call this solid lesion "cementoma of long bones". Operative therapy is not necessary.