Part of “CHAPTER 66 – RARE DISORDERS OF SKELETAL FORMATION AND HOMEOSTASIS“

Progressive diaphyseal dysplasia is a sclerosing bone disorder that is inherited in an autosomal dominant pattern, but with variable penetrance.1,6,37 Patients have defects in the gene that encodes transforming growth factor B.37a New bone formation occurs progressively along both the periosteal and endosteal surfaces of major tubular bones and is associated with pain and gait disturbance.

During childhood, the patient experiences leg pains and often has a limp.38,39 Muscle wasting and a paucity of subcutaneous fat in the extremities is common, and the gait may be waddling and broad-based. In severe cases, the axial skeleton (including the cranium) is affected. Patients may have an enlarged head, prominent forehead, proptosis, cranial nerve palsies, and a characteristic body habitus (Fig. 66-4). Sometimes puberty is delayed due to hypothalamic hypogonadotropic hypogonadism. Skeletal symptoms may remit during adolescence. Especially rare, mild, sporadic cases have been referred to as Ribbing disease.37 Such patients seem to represent new, relatively benign expressions of the disorder.