Pyle disease

Definition

A rare bone dysplasia characterized by long bones with wide and expanded metaphyses, thin cortical bone and bone fragility. The metaphyseal widening and undermodeling extends well into the diaphysis and causes in the distal femur the typical ''Erlenmeyer flask'' or ''paddle'' appearance. Bone undermodeling is also seen in the tubular bones of the hands where there is lack of diaphyseal constriction. Common clinical features include genua valga, big clavicles and dental anomalies. Mild hyperostosis of the skull and mild platyspondyly can also be observed on radiographs.