No abstract

Bone mineral measurements with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) were compared with chemical analysis (ChA) to determine (1) the accuracy and (2) the influence of bone marrow fat. Total bone mass of 19 human femoral necks in vitro was determined with QCT and DXA before and after defatting. ChA consisted of defatting and decalcification of the femoral neck samples for determination of bone mineral mass (BmM) and amount of fat. The mean BmM was 4.49 g. Mean fat percentage was 37.2% (23.3%-48.5%). QCT, DXA and ChA before and after defatting were all highly correlated (r > 0.96, p < 0.0001). Before defatting the QCT values were on average 0.35 g less than BmM and the DXA values were on average 0.65 g less than BmM. After defatting, all bone mass values increased; QCT values were on average 0.30 g more than BmM and DXA values were 0.29 g less than BmM. It is concluded that bone mineral measurements of the femoral neck with QCT and DXA are highly correlated with the chemically determined bone mineral mass and that both techniques are influenced by the femoral fat content.

The radiological appearance of giant cell tumors (GCT) in the developing skeleton was retrospectively assessed in 49 (10.6%) of the 462 patients with GCTs seen in consultation by the Netherlands Committee on Bone Tumors. There were 31 female and 18 male patients, all below 19 years of age. Thirty-four tumors were located in short and long tubular bones, two in the tarsus, while the others were in the pelvis, vertebral spine, and a rib. Involvement of the epiphysis in tubular bones was closely related to the age of the patient: the average age of the 3 patients with a lesion in the metaphysis was 11 years, that in the 6 patients with metadiaphyseal lesions 13 years, average age in the 10 patients with epimetaphyseal lesions 17 years, and it was also 17 years in the 17 patients with epimetadiaphyseal lesions. In tubular bones with the epiphyseal growth plates still open, the epiphysis was never involved, with the exception of two epimetadiaphyseal lesions in which closure of the growth plate was difficult to establish. Assessing GCT characteristics in this study population demonstrated that epiphyseal involvement increased with age and showed; to some extent, a predominance of female patients.

Desmoplastic fibroma is a rare benign primary bone tumor, histologically identical to the extra-abdominal desmoid tumor of soft tissues. The incidence in major series of bone tumors is 0.1%-0.3%. In the present study 18 cases from the files of the Netherlands Committee on Bone Tumors are reported, with an emphasis on the radiographic features. Eight female and ten male subjects were affected, with a fairly even age distribution from the second to the seventh decade of life. The most frequent sites of involvement were the femur and the pelvis. Radiographically the lesions nearly always demonstrated benign features with respect to pattern of destruction, margins, and reactive bone formation; however, soft tissue extension was sometimes present. Although desmoplastic fibroma usually presents with pain or swelling, in 5 of the 18 cases the existence of the lesion was an accidental finding, and in 2 cases the patient had long-standing, vague complaints of pain. Though overall benign radiographic features may support the final diagnosis, the main and often troublesome histological differential diagnosis is of a low-grade fibrosoma. En bloc resection is the treatment of choice in view of the high incidence of recurrence after curettage.

Seventeen patients with nonneoplastic osseous tumors in the soft tissues of the hands and feet were retrospectively studied. Three of the patients had a reliable history of trauma. Ten patients showed periosteal reaction associated with gradual formation of an osseous soft-tissue tumor, sometimes with a peripheral zone of bone density. Histologically (also radiographically), the lesions may be mistaken for malignant neoplasms such as osteosarcoma or parosteal osteosarcoma, especially when the pathologist does not receive representative material. In this series, malignancy was suspected in eight patients. Radiologic and pathologic criteria that may be helpful in the differential diagnosis of this lesion are presented. It is important that this nonneoplastic, benign, and self-limiting process in the hands and feet be recognized and treated accordingly. Local excision is adequate therapy in most cases, with little risk of local recurrence.