Osteitis Deformans (Paget's Disease of Bone)

The roentgenologist and the orthopedist are so familiar with the radiologic picture of osteitis deformans that in most cases the diagnosis is made easily from the film. The purpose of this communication is to review the microscopic features of the disease and to correlate the conventional histologic and microradiographic appearances. The few microradiographic studies that have been reported (2, 11) have concerned only fully developed Paget's disease. Since the original description (1, 8, 12, 13) of osteitis deformans, its histologic aspects have been described by Schmorl (10), Knaggs (7), and Jaffe (5). The classic morphologic appearance is that “in which tiny fragments of lamellar bone are fitted into one another like a very irregular mosaic with little tendency for the bone fragments to be arranged about vessels to form haversian systems” (5). Materials and Method of Study Fourteen specimens (5 humeri, 6 tibiae, 1 femur, 1 skull, and 1 iliac crest) were available for study. Five specimens (4 humeri and the femur) were removed from amputated limbs in which malignant changes had occurred. In 2 cases specimens of adequate size were obtained at necropsy and the remaining 7 were removed at operation for some complication of osteitis deformans or to rule out malignancy. Blocks of bone 1 × 2 cm. were removed from the specimen with a coping saw, and sections were cut from these on a milling machine for microradiography. These sections were 150 micra thick and were further ground by the method of Frost (3) to a thickness of 75 micra or less. Two specimens were embedded in methyl methacrylate so that they could be ground to a thickness of less than 50 micra. Specimens that were to be submitted to microradiography were stored in absolute alcohol to prevent decalcification. The larger block was marked so that after decalcification in formic acid the prepared histologic specimens could be sectioned in such a way that they would be separated from the parts examined by microradiography only by the thickness of the saw cut. After decalcification the large block was embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Polarized light was used to study unstained sections; in addition, the sections examined by microradiography were decalcified and then studied under polarized light. The technics were identical with methods we have reported previously (6). Classification of Morphologic Findings For convenience we have classified the morphologic findings into three types. The first is sclerotic-appearing Paget's disease, called by Jaffe “fully developed osteitis deformans.” The roentgenologist recognizes this as the most common type (Fig. 1, a). The second is early or porotic osteitis deformans, usually recognized radiologically as an early form of the disease (10). Jaffe referred to the new osseous trabeculae of this type as connective-tissue bone (Fig. 1, b). The third form we prefer to call “presarcomatous osteitis deformans.”