Bone histomorphometry in children with newly diagnosed acute lymphoblastic leukemia.

The objective of this study was to obtain insight into bone formation and resorption in children with newly diagnosed untreated acute lymphoblastic leukemia (ALL). In 23 consecutive children with ALL, a bone biopsy was taken from the crista iliaca posterior under ketamine anesthesia, together with the diagnostic marrow aspiration, before any treatment was given. Histomorphometric assessment was done of bone volume, bone area, trabecular thickness, osteoid volume, osteoid area, osteoid width, number of osteoblasts, erosion area, and number of osteoclasts. Data were analyzed in age groups under and over 10 y and compared with biopsies from 15 children, obtained during the work-up for other malignancies (only patients without bone marrow involvement were included). In ALL patients, bone volume and trabecular thickness were decreased in children <10 y. In patients >10 y, these parameters were not significantly different from the controls; bone densitometry showed no significant loss of bone in patients >10 y as well. Numbers of osteoblasts and osteoid surface occupied with osteoblasts were reduced in both age groups, as was the number of resorbing osteoclasts. No indications of osteomalacia were found. Childhood ALL results in a reduced number of both osteoblasts and osteoclasts, with a subsequent reduced osteoid formation and reduced bone resorption. This leads to a reduced bone volume and trabecular thickness, especially in younger children. In adolescents, the disturbance of bone (re)modeling is less serious, probably because of the strong stimulus on bone formation of sex hormones. The skeletal impairment at diagnosis is potentially reversible.