First described by Pyle, Metaphyseal dysplasia is a rare AR disorder characterized by splaying or fraying of the ends of the long bones due to failure of metaphyseal modeling.

It’s a benign condition; the affected individuals have a normal lifespan.Manifests most commonly in late childhood.

The skeleton of a newborn with Pyle’s disease may be overly radioopaque, simulating osteopetrosis. With growth, most bones assume a normal density, but there is failure of metaphyseal modeling, producing splaying or an Erlenmeyer flask deformity.The cortex in involved area is thinner and is predisposed to fracture.

The lower extremity is more markedly affected than upper extremity. The most commonly involved bones are distal femur, tibia (proximal and distal), and proximal fibula.

Craniofacial manifestations include hypoplasia of the sinuses and hyperostosis of the calvaria and mandible, with ocular hypertelorism.

Vertebra plana or platyspondyly with increased density of the central bodies is also associated.