Spinal involvement in Pyle's disease.

Abstract

Pyle's disease is a rare skeletal dysplasia involving the metaphyses of long bones. To date, spinal involvement has been only rarely described in the literature. To show that spinal changes, which are an expression of the same growth defect of the long bones, are an important and constant sign of the disease in the families studied. The radiographic skeletal changes in five patients have been observed. The pathognomonic metaphyseal widening of tubular bones (known as the 'Erlenmeyer flask sign') was associated with the spinal changes in all cases. Radiographic findings in the spine varied from moderate platyspondyly to the bodies having the appearance of a biconcave lens. This may be attributed to two main causes: (1) a defect in the modelling process of the vertebrae (comparable to that observed in the metaphyses) and (2) chronic pathological fractures secondary to osteoporosis (a typical feature of Pyle's disease). The finding of platyspondyly of varying severity widens the spectrum of radiographic findings in this disease and can assist in diagnosis.