Phosphaturic mesenchymal tumours (PMT) in the sinonasal region are rare. Patients can present with local nasal symptoms or with systemic symptoms of tumour induced osteomalacia. Distinctive histological features and biochemical derangements aid clinicians in the diagnosis. We report a case of a 45 year old female who presented with sinonasal PMT and consequent tumour induced osteomalacia in our institution. The patient was diagnosed to have sinonasal PMT in the left nasal cavity after presenting with epistaxis. She subsequently defaulted clinical follow-up and re-presented 2.5 years later with symptoms of tumour induced osteomalacia including immobility & multiple atraumatic fractures. Resolution of her clinical symptoms and metabolic abnormalities were seen after endoscopic resection of PMT. She remains disease free as of 1 year follow-up. This case highlights the challenges in diagnosing sinonasal PMT & clinical considerations in the management of PMT. Surgical resection remains the mainstay of treatment with adjuvant radiotherapy in cases of incomplete resection or recurrence. Post-operative surveillance includes clinical and biochemical surveillance with repeat FGF-23 levels.