Pyle disease (metaphyseal dysplasia) presenting in two adult sisters

Abstract Pyle's disease is an extremely rare skeletal disorder characterized by a benign course and an autosomal recessive genetic pattern of inheritance. Its causal mutation is still unknown. In the medical literature, fewer than 30 cases have been described to date. We report the case of two female siblings, daughters of consanguineous parents, referred to the radiology department complaining of genu valgum. Laboratory tests showed no other relevant findings. Conventional radiography plain films revealed Erlenmeyer flask deformity in bilateral femorotibial metaphyses, metaphyseal flaring of long bones, and mild sclerosis of the skull base. The clinicoradiological dissociation, along with the characteristic imaging findings, was consistent with the diagnosis of Pyle's disease. Intervention is not required in most cases, but orthopedic treatment may be required for genu valgum or fractures. Therefore, these cases emphasize the pivotal role conventional radiography plays in the correct diagnosis of this rare entity, allowing for appropriate genetic counseling.