Hypophosphataemic Osteomalacia in Fibrous Dysplasia

We describe three patients with fibrous dysplasia of bone in whom there was evidence of hypophosphataemic osteomalacia or rickets. Two of the patients had polyostotic fibrous dysplasia and osteomalacia. The third was a child with fibrous dysplasia of the facial and cranial bones and rickets. In all cases the manifestations of osteomalacia or rickets were controlled with large doses of vitamin D. In the child the rickets and hypophosphataemia ceased when most of the bone affected by fibrous dysplasia was surgically resected. Previously reported cases of the association between fibrous dysplasia and hypophosphataemic osteomalacia are reviewed. We suggest that these cases are analogous to the syndrome of ‘tumour rickets’ where hypophosphataemia appears to be due to the presence of a mesenchymal tumour and regresses when the tumour is removed.