Case report 622. Multiple cartilaginous exostoses.

The case is presented of multiple cartilaginous exostoses involving the right and left metatarsals and phalanges, left scapula, ends of several distal ribs, and the spinous processes of several thoracic and lumbar vertebrae in a 3-month-old female Scottish terrier dog. Radiographical studies showed circumscribed expansile lesions in the affected bones. The dog developed neurological deficits 3 weeks later. Myelography displayed extradural compression of the opaque column at several thoracolumbar vertebrae. The biopsy specimen from an affected phalanx consisted of trabecular bone and hemopoietic tissue covered by a thin cap of hyaline cartilage. The dog was euthanized due to the poor prognosis. At autopsy, the surface of the affected bones was covered by a bluish-white, smooth, undulating cartilage cap. Histopathologically, the cartilaginous cap consisted of hyaline cartilage without a reserve zone, and abnormal endochondral ossification. The hereditary nature and the malignant transformation of multiple cartilaginous exostoses in the dog have been considered.