Octreotide Therapy for Tumor-Induced Osteomalacia
Jochen Seufert, M.D., Katja Ebert, M.D., Justus Müller, M.D., Jochen Eulert, M.D., Christian Hendrich, M.D., Edgar Werner, M.D., Norbert Schütze, Ph.D., Georg Schulz, M.D., Werner Kenn, M.D., Hubert Richtmann, M.D., Klaus-Dieter Palitzsch, M.D., and Franz Jakob, M.D.
Tumor-induced osteomalacia (also known as oncogenic osteomalacia)1 is a rare disorder characterized by phosphaturia, hypophosphatemia, and osteomalacia mimicking the clinical phenotype of either X-linked2 or autosomal dominant3 hereditary hypophosphatemic rickets. Tumor-induced osteomalacia develops because of tumors that are predominantly of benign mesenchymal origin4 but that may occasionally be malignant, as was recently reported.5 Surgical removal of the tumor relieves all symptoms. Hemangiopericytoma is the most dominant histologic entity in tumor-induced osteomalacia.4,6 Paraneoplastic secretion by the tumor of an unknown factor or factors — termed "phosphatonins" — causing renal tubular phosphate wasting has been proposed as the pathogenic mechanism.7
We describe an adult man who had hypophosphatemic osteomalacia for several years before an octreotide scan revealed a mesenchymal tumor in his left thigh. Moreover, subcutaneous administration of octreotide, a synthetic somatostatin analogue, abolished renal tubular phosphate wasting before subsequent surgical removal of the tumor.