Oncogenic Osteomalacia Due to Recurrent Phosphaturic Mesenchymal Tumour in the Obturator Canal

Abstract

Phosphaturic mesenchymal tumour is a neoplasm which releases phosphaturic substances known as the fibroblast growth factor-23 (FGF-23). It results in increased renal excretion of phosphate, decreased blood phosphate levels, tumour-induced osteomalacia (oncogenic osteomalacia) and secondary hyperparathyroidism. A 61-year-old lady presented with complaints of generalised tiredness and body ache of 1-year duration. She had previous history of tumour-induced osteomalacia due to mesenchymal tumour in the right inguinal region and tumour excision in 2010. Biopsy at that time was suggestive of mesenchymal tumour. On further evaluation, she was found to have hypophosphatemia, phosphaturia and secondary hyperparathyroidism. Contrast-enhanced MRI showed a doubtful lesion in the right obturator canal, which was further confirmed by 68Ga-DOTATOC whole body PET/CT. She underwent complete excision of the lesion followed by Prolene mesh repair of the defect. Phosphaturia and hypophosphatemia improved after excision. She was symptom free after 1 month. She developed mild seroma over the surgical site after 1 month, which settled on radiological drainage. Phosphaturic mesenchymal tumour is a rare cause of oncogenic osteomalacia and secondary hypoparathyroidism. 68Ga-DOTATOC whole body PET/CT is helpful in localising the lesion. Complete excision of the tumour ensures complete recovery of the patient from the disease.