Clin Osteol 2026; 31(1): 36-44 | DOI: 10.36290/clo.2026.005

Tumor-induced osteomalacia - a rare cause of hypophosphatemia in patients at an osteology clinicMain theme

Henrieta Halmová¹, Filip Halm², Peter Sečník³, Andrej Vondrák⁴, Ján Koreň⁵, Mojmír Ducár⁵

¹ OSTEOMED, s. r. o., Endokrinologická ambulancia, Lučenec

² Nemocnice Na Homolce, Praha

³ SK-Lab, s. r. o., Lučenec

⁴ Izotopcentrum, s. r. o., Nitra

⁵ Unilabs Slovensko, s. r. o., Banská Bystrica

Tumour-induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by benign tumours of the mesenchymal origin. It is characterized by the excessive production of fibroblast growth factor 23 (FGF23), which subsequently leads to hypophosphatemia and osteomalacia. In the article, we present a case report of the 57-year-old female patient who, after a relatively protracted diagnostic process, was diagnosed with TIO caused by the benign tumor of mesenchymal origin, called sinonasal glomangiopericytoma. In this case report, we further discuss the pathophysiology of a hypophosphatemic osteomalacia, its differential diagnosis and the treatment options for the tumour-induced osteomalacia.

Keywords: tumor-induced osteomalacia, parathyroid hormone, fibroblast growth factor 23, fractional excretion of phosphate, sinonasal glomangiopericytoma, 68Ga DOTA-TATE PET-CT.

Accepted: March 25, 2026; Published: March 30, 2026  Show citation