Twenty-one patients, two months to seventy-eight years old, with
clinically diagnosed osteopetrosis showed radiographic and histological
variations in the formation of radiodense skeletal tissue at all ages.
Pathologically the abnormal tissue was composed of both lamellar bone and
calcified cartilage. We deduced that the abnormality or abnormalities of
osteoclast function that cause the observed changes vary in severity from
time to time in individual patients. Periods of remission in the less
severely affected patients apparently had permitted the formation of
bone-marrow spaces and allowed hematopoietic tissue to form in these
patients. The patients who died of the disease did so because of anemia or
its resulting complications. Some children with a lethal form of the
disease had rickets and epiphyseal fractures in addition to the
osteopetrosis. Focal areas of osteomalacia were observed in two specimens
from adults. Traumatic and stress fractures were frequent complications at
all ages.