Summary

A 51-year-old man presented with generalised bone pain. Initial evaluation revealed a low serum phosphorus level and elevated urinary phosphorus excretion. Aminoaciduria was normal. Standard imaging showed only minimal changes. The patient was treated with daily oral supplementation with phosphate (1 g/day) and 1,25-dihydroxyvitamin D3 (1 μg/day) to maintain euphosphataemia. In spite of the fact that this treatment was maintained for 3 years, there was no modification of renal phosphate clearance. A diagnosis of hypophosphataemic osteomalacia with renal phosphate wasting was proposed. Therefore, tumour-induced osteomalacia was suspected, triggering a diagnostic workup to find the primary tumour. These tumours are known to express somatostatin receptors, so whole body positron emission tomography (CT) imaging was performed after intravenous administration of ⁶⁸Ga-DOTA-TOC (⁶⁸Ga-DOTA-D-Phe1-Tyr3-pentreotide). A solitary intense hot spot was detected in soft tissue near the right femoral internal condyle. Based on this result, curative resection of the tumour was performed.