Chondrodysplasia punctata--rhizomelic form. Pathologic and radiologic studies of three infants.

Pathologic, ultrastructural and radiologic studies are described on 3 infants with the rhizomelic form of chondrodysplasia punctata. Radiologic criteria in the young infant include radiolucent coronal clefts dividing all or most of the thoracic and lumbar vertebral bodies, short humeri with flared metaphyses and punctate calcifications commonly present adjacent to the ossified ischial and pubic bones and less commonly in other locations. In late infancy and childhood the radiologic criteria include demineralization in all bones with slow maturation, flat vertebral bodies, short humeri and femora, metaphyseal flaring, especially in the distal humerus, proximal femur and proximal tibia, immature shape of pelvis, and disappearance of the punctate calcifications with advancing age. The histologic changes of the resting cartilage include areas of degenerating cartilage which had become partially calcified, cystic changes with severe disturbance of the maturation of the cartilage at the physial plate, and the formation of cancellous bone directly on resting cartilage. Ultrastructural changes are characterized by degeneration of chondrocytes, delicate collagenous fibrils without visible periodicity, and the presence of flocculent material within greatly distended endoplasmic reticulum.