Diastropic dwarfism: a histochemical and ultrastructural study of the endochondral growth plate.

Chondro-osseous tissue from five patients with diastropic dwarfism was studied by histologic, histochemical, and electron microscopic methods. The major abnormalities observed were: 1) irregular distribution of chondrocytes undergoing degeneration in the resting cartilage; 2) abnormal distribution of collagens in the resting cartilage; 3) a spectrum of fibrous matrix lesions in the resting cartilage which ranged from focal areas of aggregated collagen fibrils to large cystic lesions in which intracartilagenous ossification occurred; and 4) shortened, irregular cellular columns within the growth plate which were occasionally disrupted by matrix lesions extending from the resting cartilage. These alterations in chondro-osseous morphology have not been observed in any of the other skeletal dysplasias examined to date and appear to be pathognomonic for this disorder.