A comparative study of periosteal new-bone response in metastatic bone tumors (solitary) and primary sarcomas.

Abstract

The radiographic appearance of a solitary metastatic focus in bone is frequently mistaken for a primary malignant bone tumor. As Lodwick pointed out, “the solitary metastatic lesion of bone is the one which usually offers the real challenge in differential diagnosis” (3). Often, the distinguishing feature of a primary sarcoma is the presence of an associated periosteal reaction which authors have stated to be absent or scant in metastatic bone lesions. This investigation was initiated to determine if periosteal new-bone formation is in fact rare in metastasis and, therefore, a roentgenographic finding of value in differentiating primary from secondary bone tumors. Clinical Material A. Metastatic Tumors: In a period of six years, 35 patients with solitary metastatic lesions in bone were studied. This study was a selective review as only patients with isolated metastatic foci in bone were included. These included primarily lesions involving the appendicular skeleton, those most difficult to differentiate from primary bone sarcomas. Histologic documentation of the lesion was available in most cases. The presence and type of periosteal reactions were recorded from the roentgenograms. The types of periosteal responses were classified into one of four categories: (a) the lamellated reaction (onion peel), (b) a perpendicular or spiculated sunburst appearance, (c) a dense periosteal reaction which is difficult to differentiate from thickened cortical bone and often associated with osteoblastic metastases, and (d) the Codman or reactive triangle at the margin of the lesion. Patients with callus formation at the site of pathologic fracture were excluded from the clinical study because it was difficult to decide from the radiographs what represented normal fracturehealing and what represented periosteal response to tumor. There were a variety of primary sites in the metastatic series; 13 in all. When periosteal reaction was present, however, the most frequent primary tumors noted were in the gastrointestinal tract, prostate, kidney, lung, and adrenal gland. In fact, the finding of a solitary metastasis to the femur from a latent primary focus in the lung masquerading as a reticulum-cell sarcoma stimulated this study (Fig. 1). Only after biopsy was the true nature of the lesion disclosed. Thirteen of 35 patients in this group showed radiographic evidence of one or more types of periosteal reaction. In most instances the new-bone responses were varied, but in patients with osteoblastic metastasis a dense periosteal reaction was frequently noted (Fig. 2). The most pronounced periosteal responses were in metastases from the colon, prostate, and adrenal glands (neuroblastoma) (7). The incidence of reaction was 37 per cent, and the distribution of cases is illustrated in Figure 3. B. Primary Bone Tumors: A comparative study of 41 patients with primary bone a periosteal reaction. Because osteosarcomas can produce tumor bone in the soft tissues, however, it is difficult to be certain if one is dealing with periosteal non-tumor bone or tumor bone o