Tumour-induced osteomalacia due to phosphaturic mesenchymal tumour of the ethmoid

Abstract

Tumour-induced hypophosphatemic osteomalacia is often due to mesenchymal tumours. Surgical resection of tumour gives complete relief. We present the case of a 66-year-old male who sustained fracture of the hip after a trivial fall. After hip replacement surgery his proximal muscle weakness did not improve. On evaluation he had hypophosphatemia with hyperphosphaturia, raised fibroblast growth factor-23 levels. A gallium 68 (68Ga) - radiolabeled somatostatin analogue 1,4,7,10 – tetra azacyclododecane – N,N1, N11,N111 – tetraacetic acid (DOTA) 1-NaI3 – octreotide (NOC) positron emission tomography computed tomography revealed a somatosatin receptor avid polypoidal lesion in left posterior ethmoid sinus measuring 1.5 ˣ 1.6 cm likely representing mesenchymal tumour and retention cyst/polyp in left sphenoid sinus. Patient underwent a navigation assisted minimally invasive sinus surgery for removal of polypoidal lesion. Histopathological examination confirmed phosphaturic mesenchymal tumour.

Keywords

• phosphaturic mesenchymal tumor
• fgf-23 levels
• hypophosphataemia
• proximal muscle weakness