Osteoid osteoma--osteoblastoma.

Abstract

In view of the clinical and pathological similarities, osteoid osteoma and osteoblastoma can be considered variants of one benign osteoblastic process. We suggest classifying these lesions according to their location in the bone, for that location determines the nature of reaction evoked. For lesions arising within compacta, we suggest the name cortical osteoblastoma (synonymous with osteoid osteoma). For lesions arising in the spongiosa, we propose the term spongious osteoblastoma (synonymous with benign osteoblastoma). A series of 24 cases is reviewed. Eleven were of the cortical type, characterized by a striking perifocal bone reaction with nidus size averaging 1.3 cm. Thirteen were classified as a spongious osteoblastoma, with slight or no perifocal bony reaction. Frequently the nidus showed calcification and a thin ring of sclerotic-appearing trabeculae. The nidus size averaged 2.5 cm. The cortical type was more frequent in the diaphysis of long bones while the spongious type was more common in the spine, metaphyses, and short bones. Cancer 33:1075-1081,1974. N 1935, JAFFE~~ DESCRIBED A NEWLY RECOGI nized bone lesion, occurring in both spongy and cortical bone, which he named “osteoid osteoma.” In 1954, Dahlin and Johnson4 called attention to an uncommon benign bone tumor that they called “giant osteoid osteoma,” involving cancellous or medullary bone, large in size and often eccentrically located within the medullary cavity. Those arising in long bones were associated with considerable cortical thickening. They remarked on the histologic similarities between this lesion and the secalled osteoid osteoma. These authors differentiated the two lesions according to size, tendency to erode through the cortex, the presence of striking bony sclerosis, and the associated histologic patterns. Jaffel3 and LichtensteinZ2 in 1956 independently proposed the term “benign osteoblastoma” for a rather vascular, osteoid- and boneforming lesion. In discussing the differential diagnosis, Jaffe stated: “There can be no doubt that the histologic tissue pattern of the benign osteoblastoma bears a certain similarity to that of the osteoid osteoma. The only