Oncogenic Osteomalacia: A Case Report and Literature Review

Abstract

Oncogenic Osteomalacia or Tumor Induced Osteomalacia (TIO) is a rare paraneoplasmatic syndrome characterized by multiple automatic pathological fractures as well as by severe hypophosphatemia. The etiology is not known, but its pathophysiology is associated with a very small mesenchymal tumor which is related to the Fibroblast Growth Factor 23 (FGF 23). Clinically the patient has numerous automatic fractures of the upper and lower limbs and of the spine, with bone and muscular pains. Hypophosphatemia, phosphaturia and increased alkaline phosphatase are the laboratory findings. Finding the tumor can be a major diagnostic challenge and the radical excision is the treatment of choice. A female patient, 47 years old, senior nurse, healthy in general, revealed a progressive weakness of the lower legs during the last two years, generalized myopathy and pathological fractures in pelvis, hips, humerus, sternum, clavicles, spine, radius and knees, symmetrical in both sides, left and right. Phosphorus and vitamin D were found very low and FGF 23 very high. Scan, CT and MRI were normal. The PET revealed a very small lesion in the base, under the tongue. The tumor was removed and the biopsy confirmed the phosphaturic mesenchymal tumor. Very soon the patient recovered, the fractures were united and today five years postoperatively, she is very well and free of the disease.