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

Pycnodysostosis, an autosomal recessive disorder, perhaps affected the French impressionist painter Henri de Toulouse-
Lautrec.2,6 Patients present in childhood with disproportionate short stature, a relatively large cranium, frontooccipital prominence, small facies, obtuse mandibular angle, small chin, dental malocclusion, high palate, exophthalmos, blue-tinged sclerae, a pointed and beaked nose, and short, clubbed fingers with hypoplastic nails. Recurrent fractures, with deformity, scoliosis, kyphosis, and genu valgum, may occur. Generalized uniform osteosclerosis increases with age but is not accompanied by the modeling defects of osteopetrosis.5 Unlike in osteopetrosis, the fontanelles remain open (especially the anterior; Fig. 66-3), radiodense striations and endobones do not occur, wormian bones may be present near the parietal sutures, the mandibular angle is obtuse, and hypoplasia of the facial bones, clavicles, and terminal phalanges is present.