Hypophosphataemia-inducing mesenchymal tumour in the foot.

Tumour-induced (or oncogenic) osteomalacia is a paraneoplastic syndrome characterised by progressive fatigue, muscle weakness, bone pain, non-healing and recurrent fractures caused by mesenchymal tumours that secrete proteins that inhibit renal phosphate transport and 1α-hydroxylation of 25-OH-vitamin D. The potentially curative treatment of choice is complete surgical excision of the tumour.