EYES2024 ESE Young Endocrinologists and Scientists (EYES) 2024 Calcium and Bone (9 abstracts)
1Department of Endocrinology, Saint Spiridon Emergency Hospital, Iaşi, Romania; 2University of Medicine and Pharmacy "Grigore T. Popa", Iaşi, Romania
Introduction: Tumor-induced osteomalacia (TIO), is a rare paraneoplastic syndrome caused by mesenchymal tumors which are typically benign, small and slow-growing. They express and secrete fibroblast growth factor 23 (FGF23), leading to decreased reabsorption of phosphate and production of 1,25-dihydroxyvitamin D by the kidney. The resulting hypophosphatemia causes osteomalacia, bone pain, muscle weakness, and fractures.
Case presentation: This is the case of a 50 year old woman, referred to our department with a long history of diffuse bone pain and progressive muscle weakness, which finally led to the impossibility of walking without support. She associated vertebral osteosclerosis with spinal disc herniation and spinal stenosis from the age of 44, as well as multiple fragility fractures of the vertebrae, hips, femur, ribs and even scapula due to hypophosphatemic osteomalacia. FGF 23 levels were elevated, along with low serum phosphate, normal vitamin D, and normal serum calcium which implied necessary finding the secreting tumor. Multiple imagistic techniques were used in the attempt of localizing the source (repeated CTs, 18F-FDG PET-CT) with no specific results. Five years after the onset of symptoms, a tumor was localized in the left ethmoidal region of the skull using Tektrotyd scintigraphy followed by cerebral MRI. Excision of the tumor led to normalization of FGF-23 and phosphate levels, as well as complete resolution of all musculoskeletal symptoms.
Conclusion: TIO is a rare syndrome with non specific symptoms, which is often misdiagnosed with a variety of skeletal, rheumatologic or neuro-psychiatric diseases, leading to a significant decrease in quality of life and severe functional impairment, as we can see in our patient. FGF23 secreting tumors are difficult to find, therefore definitive treatment is delayed. These facts highlight the importance of considering TIO and including the measurement of serum phosphate in any patient with fractures, persistent bone pain and muscle weakness.