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

Endosteal hyperostosis is inherited either as a clinically severe autosomal recessive disorder (sclerosteosis or van Buchem disease) or as a relatively benign autosomal dominant condition (Worth type).6 The clinical and radiographic manifestations, however, are similar.1,6,45 During puberty, progressive asymmetric enlargement of the mandible occurs. Occasionally, facial palsy or deafness is caused by cranial nerve entrapment, but the head circumference is normal. Serum alkaline phosphatase activity may be increased in van Buchem disease. Radiographic abnormalities include sclerosis of the axial skeleton and the skull (where the table may be wide), mandibular enlargement, and thickening of the diaphyses of long bones due to selective endosteal hyperostosis (bones remain properly shaped).5 Some cases reported as van Buchem disease have features suggesting sclerostenosis or craniodiaphyseal dysplasia.46 Previously, sclerostenosis had been differentiated from van Buchem disease because patients with the former condition were of excessive height and had syndactyly; however, both conditions map to chromosome 17q12-q21; thus, they may be allelic disorders.47 No effective medical treatment exists.