An exercise in radiologic-pathologic correlation.

Abstract

In Bone the roentgenogram is in fact the gross specimen and may offer more information about the nature of the disease than does the actual gross material in the pathology laboratory. The diagnosis may be suggested by the kinds and degree of mineralization, for example. Radiographs of bone give five major types of information: the location of the lesion within the bone, the broad category to which the disease process belongs (trauma, inflammation, anomalies, neoplasms, metabolic disease, circulatory disturbances, mechanical adaptations), the presence or absence of mineralization, the degree and pattern of destruction of bone (a clue to the rate at which the disease is progressing), and the degree and pattern of bone repair seen in the form of mineralized material. The case presented this month will be analyzed on the basis of such findings. Radiology The findings in Figures 1, A and B, can be outlined as follows: The lesion is located in the lower diaphysis of the ulna and does not involve either epiphysis or metaphysis. The border between disease and normal bone is sharply defined (there is no ragged, ill-defined periphery as might be seen in a rapidly invasive lesion). The bone is obviously destroyed over a fairly wide area, and the laminagram demonstrates that the intraosseous portion of the lesion is fairly extensive. The lesion is expansile, eccentric, devoid of any mineralized matrix, and it expands the bone in every direction except dorsally. On the radial side it has outrun the formation of new cortex. Buttresses at either end indicate the limits of the expansion mechanism, while the gap between the buttresses indicates the lesion expanded faster than the new periosteal bone could form in the middle of the lesion. A few coarse perpendicular streamers signal the direction of growth outward from within the bone and represent thickened areas of nearly successful attempts to contain the lesion. Differential Discussion of the Radiographic Findings: These data indicate a disease beginning within the bone which is breaking out at moderate speed, but not spreading rapidly up or down the bone. There is no evidence of trauma. The lesion is too recent and incomplete for a developmental anomaly. Most metabolic diseases would show more diffuse findings. An inflammation of this magnitude, breaking out at this rate, would have provoked a much greater bone sclerosis and periosteal reaction. Thus, a neoplasm that has arisen within the diaphysis is the favored diagnosis. Diaphyseal lesions include chondromas, osteoblastomas, chondromyxoid fibromas, angiomas, cysts, lipomas, central (desmo-plastic) fibromas, nonossifying fibromas, and fibrous dysplasia. But none of these benign lesions usually breaks out of bone as this one has. Therefore, metastatic tumors or malignant variants of some of the above categories must be considered.