Surgically curable hypophosphatemic rickets. Diagnosis and management.

Childhood hypophosphatemic rickets (HR) is most often caused by a defect in renal tubular resorption of filtered phosphorus. However, HR can also be caused by secretion of a phosphaturetic factor from a tumor. The presentation of patients with the different HR syndromes may be identical. Distinguishing between the HR syndromes is essential, however, because HR caused by renal defect requires life-long therapy with Vitamin D and phosphate replacement, but tumor-associated HR is cured by removal of the tumor. A case of hemangiopericytoma occurring in bone and causing HR is reported. Children with HR typically have normal levels of serum calcium and parathyroid hormone but very low levels of serum phosphorus. In a child with HR, the following features should prompt a thorough evaluation for a causative tumor: lack of other family members who have hypophosphatemia; presence of aminoaciduria, particularly glycinuria. Causative lesions are most commonly found in the bone or skin.