Tumor-induced osteomalacia.

Area of Science:

• Endocrinology
• Oncology
• Nephrology

Background:

• Tumor-induced osteomalacia (TIO), or oncogenic osteomalacia, is a rare paraneoplastic syndrome.
• It presents with hypophosphatemia due to impaired renal phosphate reabsorption and abnormal vitamin D levels.
• Tumors often secrete fibroblast growth factor 23 (FGF23), disrupting phosphate and vitamin D metabolism.

Purpose of the Study:

• To summarize the understanding of TIO, including its pathophysiology, diagnosis, and management.
• To highlight the diagnostic challenges and effective localization techniques for TIO-associated tumors.
• To discuss treatment strategies and patient prognosis.

Main Methods:

• Review of literature on TIO, focusing on clinical presentation, biochemical findings, and tumor characteristics.
• Discussion of diagnostic approaches, including laboratory tests, imaging, and specialized techniques like somatostatin-receptor functional scintigraphy.
• Analysis of treatment outcomes following tumor resection and alternative management for unresectable cases.

Main Results:

• TIO is characterized by hypophosphatemia and osteomalacia, often caused by small, difficult-to-locate tumors producing FGF23.
• Differential diagnosis is crucial, distinguishing TIO from inherited and acquired phosphate disorders.
• Somatostatin-receptor functional scintigraphy significantly aids tumor localization.
• Complete tumor removal generally leads to favorable prognoses, though recurrence is possible.

Conclusions:

• TIO diagnosis requires considering hypophosphatemia and osteomalacia, necessitating differentiation from other phosphate-wasting disorders.
• Effective tumor localization is critical and can be facilitated by advanced imaging techniques.
• Surgical resection offers the best prognosis, while medical management with phosphate and vitamin D is an option for unresectable tumors.