Lethal osteosclerotic osteochondrodysplasia with platyspondyly, metaphyseal widening, and intracellular inclusions in sibs.

We report on a previously undescribed form of lethal osteosclerotic skeletal dysplasia in sibs from nonconsanguineous parents. Radiographic findings included increased density in the base of the skull, clavicles, vertebrae, ribs, and the metaphyseal regions of the long bones. There was midface hypoplasia, a large anterior fontanel, micrognathia, and hypoplastic, wafer-thin vertebrae. The clavicles, ribs, metacarpals, metatarsals, and phalanges were especially thickened and widened. The long bones were shortened with flared metaphyses. Chondroosseous morphology of resting cartilage and growth plate was relatively normal, but there was hypercellular cortical and trabecular bone, and marrow fibrosis. Ultrastructurally, the resting chondrocytes, osteoblasts, and nonhematopoietic marrow cells had dilated rough endoplasmic reticulum (inclusion bodies). The radiographic and morphologic characteristics in this case are unique and differ from those seen in other previously reported lethal osteosclerotic skeletal dysplasias.