Detection of the primary tumor site in tumor-induced osteomalacia by indium-111 octreotide scintigraphy: A case report

Abstract

We report a 31-year-old woman with tumor-induced osteomalacia suffering from slowly progressive bilateral muscle weakness predominantly in the proximal muscles and multiple bone pains for the past 2 years. She was unable to walk or raise her arms above the shoulder. We suspected tumor-induced osteomalacia due to decreased serum phosphate and 1α, 25 (OH)₂-vitamin D3 levels, low percentage of tubular reabsorption of phosphate (%TRP), adult onset, and no family history of osteomalacia. Regular imaging examinations could not detect the location of the primary tumor; however, indium-111 octreotide scintigraphy detected the causative primary mesenchymal tumor in the right sole. Pain and muscle weakness improved promptly after tumor resection, and she was able to walk 6 d postoperatively. This is the first case report in Japan describing the detection of the primary tumor site by indium-111 octreotide scintigraphy.