Osteosclerotic metaphyseal dysplasia: a skeletal dysplasia that may mimic lead poisoning in a child with hypotonia and seizures

Abstract

We report the case of a 23-month-old male with hypotonia, developmental delay, and complex seizures. Radiographs revealed profound sclerosis of the metaphyses and epiphyses of the long and short bones in the extremities, with a unique pattern of distribution. Sclerosis also involved the anterior ribs, iliac crests, talus, and calcaneus. The skull and vertebral bodies appeared unaffected. Blood lead levels were normal. We believe that this constellation of clinical and radiographic abnormalities closely resembles osteosclerotic metaphyseal dysplasia (OMD) due to an autosomal recessive defect. Characteristic skeletal findings were instrumental in determining the diagnosis. OMD is a very rare sclerosing bone disorder, first described in 1993. The syndrome is characterized clinically by developmental delay of a progressive nature, hypotonia, elevated alkaline phosphatase, and late-onset spastic paraplegia. We encountered a young child with these neurologic symptoms who displayed sclerotic metaphyseal changes on hand radiographs obtained to determine the bone age. Lead poisoning, a known cause of metaphyseal sclerosis, was initially suspected. Careful analysis of the metaphyseal bone changes helped to distinguish this bone dysplasia from lead poisoning and other causes of metaphyseal sclerosis.