Axial Osteomalacia

Axial osteomalacia is a rare osteosclerotic disorder first described by Frame et al. (1961). Characteristically, trabecular bone has 'a unique coarsening and spongelike appearance in the x-rays of the axial skeleton.' Radiographically, the skull and appendicular skeleton are normal. Vague chronic axial skeletal pain is the presenting symptom in most patients. Despite osteosclerosis and normal circulating levels of calcium, inorganic phosphate and alkaline phosphatase, bone biopsy specimens show osteomalacia. Until the report of Whyte et al. (1981), 10 cases had been described, all in middle-aged or elderly white men. Whyte et al. (1981) showed that it can occur in blacks, in females, in family clusters, and in association with polycystic kidney and liver disease. They reported affected mother and son. The son, who showed x-ray changes as early as age 22, had an unexplained myopathy characterized by proximal weakness, persistently elevated circulating creatine phosphokinase levels, and myopathic changes on muscle biopsy. The authors suggested that this is a disorder of vitamin D action. (Muscular weakness is conspicuous also in vitamin D deficiency.) It may be a pleiotropic disorder with polycystic kidney as a feature. This may be the same disorder as that described elsewhere under the designation osteomesopyknosis (166450).