The case of oncogenic hypophosphatemic osteomalacia

Abstract

Osteomalacia is a systemic bone disease, characterized by an excessive accumulation of non-mineralized osteoid and an imbalance in the organic matrix formation and mineralization. A rare cause of disease is tumor-induced osteomalacia, most often due to phosphaturic mesenchymal tumors (PMT). Usually there are benign small tumors, affecting the soft tissues and bones of any location. The basic pathogenesis of underlying oncogenic osteomalacia is a decreased renal tubular reabsorption of phosphate consequent to hyperproduction of fibroblast growth factor 23 in PMT. Clinical features are nonspecific, the average period from the symptoms onset to diagnosis reaches 3 years and at least 5 years before surgical treatment. Finding the tumour is crucial, as complete removal is curative. We present a clinical case of tumor-induced osteomalacia due to PMT required the complex differential diagnosis with other rare diseases.