Phosphaturic mesenchymal tumour in the temporal bone : a rare presentation

Abstract EN

Background : Tumour-induced osteomalacia (TIO) is a rare clinical entity in which secondary osteomalacia is induced by tumour-related products.

There is impaired reabsorption of phosphorus in the renal tubules and hypophosphatemia as a result of over expression of FGF-23 mRNA.

Treatment of choice is considered to be total or near total resection of the tumour.

Methods and results : A 49-year-old man had experienced systemic bone pain and bilateral limb weakness for several months.

He had refractory hypophosphatemia and marked elevation of serum FGF-23 level.

Magnetic resonance imaging (MRI) of the lumbar spine showed a focal lesion in the left temporal bone which was hyper metabolic on positron emission tomography (PET) scan, leading to a diagnosis of TIO.

He underwent lateral skull-base surgery after thorough evaluation of the tumour.

After the en bloc resection, FGF-23 became gradually undetectable, phosphate reabsorption normalised, and all symptoms were resolved.

Conclusions : We present the clinical features and treatment options for this most unusual manifestation of phosphaturic mesenchymal tumour in the temporal bone.