The Bone Changes of Leukemia in Children

Abstract

Leukemic bone changes are for many reasons more common, more extensive, and more varied in children than in adults. In children leukemia is usually of the acute lymphatic type, while in adults the chronic types are more common (3). The marrow of all the bones is hyperactive in childhood, but only that of the sternum, ribs, and vertebrae at a later age, so that there is numerically more opportunity for leukemic infiltration of the bones and periosteum in children. The periosteum is less firmly attached to the shafts of long bones in early life so that it is more easily elevated and stimulated to new bone production. Bone metabolism is more active and more readily disturbed in the growing bones of children. The reserve blood-forming capacity, beyond normal demands on the bone marrow, is comparatively less in children than in adults. This reduced “margin of safety” is said by Poynton and Lightwood (15) to account for some of the skeletal changes seen in children with leukemia. In attempting to meet the overload demands of the disease, the body tries to increase its blood-forming capacity by expansion of the bone marrow and subsequent atrophy and erosion of the cortex. Adults occasionally show leukemic bone changes. Craver and Copeland (5), in a radiographic study of 168 patients with leukemia, found 6 adults with demonstrable changes in the femur, sternum, humerus, pelvis, skull, metacarpals, ulna, and vertebrae in that order of frequency. Both osteosclerotic and osteoclastic changes were observed, although the latter predominated. Periosteal elevation and new bone formation were not seen. All the cases were of the leukopenic variety, and most were lymphatic in type. A few others in the series showed autopsy evidence of leukemic infiltration in the bones not demonstrable roentgenologically. Leukemic bone changes in adults have also been reported by Wintrobe and Mitchell (22), Craver (4), Forkner (9), and others. We have found in the available literature reports of 144 cases of leukemia in children with demonstrable bone changes: 138 cases were of the lymphatic type, 5 of the myeloid type, and 1 of the monocytoid type. In over 50 per cent of the series, the disease was of the leukopenic variety. The changes were of various kinds and occurred either singly or in combination in any given roentgen examination. One of the most common bone changes in childhood leukemia is periosteal elevation with new bone formation along the shafts of the long bones. This appears as a linear area of increased density parallel to the shaft but separated from it. The new bone may be smooth in outline and fairly uniform in density or it may be irregular. It may extend the entire length of the shaft or over only a small segment, and may be on one side or may completely encase the shaft. Multiple layers of new bone parallel to each other and to the shaft are sometimes present.