Oncogenic osteomalacia, or tumour-induced osteomalacia (TIO), is a rare paraneoplastic syndrome characterised by hypophosphataemia, phosphaturia, inappropriately low serum levels of 1,25-dihydroxyvitamin D for hypophosphataemia. TIO is caused by mesenchymal tumours that secrete phosphaturic substances, leading to increased renal wasting of phosphates. These tumours are very small in size and grow slowly. Localisation of these tumours has always been difficult with the available biochemical and imaging techniques. At times, despite all efforts, the tumour could not be localised. We report our experience with a 42-year-old woman with TIO where whole-body magnetic resonance imaging could not localise the tumour, a scapular haemangiopericytoma. PET/CT was helpful in the localisation of the tumour which, when surgically removed, resulted in the normalisation of biochemical parameters with clinical improvement.