Progressive diaphyseal dysplasia was found in a three-generation family including 13 affected individuals, the largest family reported to date. Our study confirms that progressive diaphyseal dysplasia, also known as Engelmann's or Camurati-Engelmann disease, is an autosomal dominant disorder with variable osseous and muscular manifestations. Disease distribution among patients, within a given patient, or even in individual bones is unpredictable. The femur is the most commonly and severely affected bone and hence most useful for radiographic screening of possible patients. Radiographs provide a meaningful assessment of disease activity and extent. The severity of symptoms is generally proportionate to severity of involvement shown by roentgenography. Exophthalmos due to osteosclerotic dysplasia of the skull occurred in more than half of the patients with progressive diaphyseal dysplasia. Twelve-year follow-up of this family, with affected individuals ranging in age from 6 months to 12 years, indicates that progressive diaphyseal dysplasia may progress or become quiescent and be remarkably inactive despite advanced osteosclerosis and structural deformity.
