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Beitragstitel FGF-23 transmitted tumor - induced hypophosphatemic osteomalacia: a rare case of a young woman with recurrent fractures
Beitragscode P64
  1. Florian Frank Kantonsspital Aarau AG Vortragender
  2. Lukas Gerber Kantonsspital Aarau AG
  3. Alexander Cornelius Kantonsspital Aarau AG
  4. Daniel Baumhoer Universitätsspital Basel (USB)
  5. Andreas Heinrich Krieg Universitäts-Kinderklink (UKBB)
Präsentationsform Poster
  • A07 - Spezialgebiet 3 | Tumore
Abstract Introduction
Tumor-induced osteomalacia (TIO) is a rare form of acquired hypophosphatemia which was first described in 1959. In TIO a mesenchymal tumor produces phosphaturic fibroblast growth factor 23 (FGF 23) and causes hypophosphatemia in adults which has been reported in about 500 cases.
Algorithms for diagnosis and treatment were established, but TIO is often diagnosed with extensive delay leading to unnecessary diagnostic and interventional procedures. Detecting the tumor remains a challenge due to small size and variable location. A genetic etiology must be excluded once TIO is suspected.
We present a case of tumor-induced osteomalacia (TIO) in a young woman of 22 years. The fibroblast growth factor 23 transmitting tumor in her left foot remained undetected for several years. She suffered multiple fractures including insufficiency fractures of both femoral necks requiring bilateral proximal femoral nailing. After phosphaturia was diagnosed any known genetic etiology was excluded. Even advanced imaging modalities (including FDG-PET) were unable to detect the clinically silent tumor until an 68Ga-DOTA-TOC-PET/CT-scan revealed a mass with paraneoplastic activity in the left foot. Complete resection of the tumor proved to fully cure her condition after 9 years. Serum phosphate levels returned to normal within days and bone densitometry showed normal t-scores within months.
TIO is a rare but increasingly recognized condition, caused by mostly benign and slow-growing phosphaturic mesenchymal tumors secreting FGF-23 (~70-80% of all cases). In 60% of cases (including this one) a FN1-FGFR1 fusion transcript is detectable. This case illustrates the common difficulties in diagnosing and treating these tumors with a delay of nine years between the onset of symptoms and curative tumor surgery.
In a young patient with recurrent fractures and unknown cause of osteomalacia the index of suspicion should be set rather high, and all measures should be taken to establish an early diagnosis. This will spare the patient from long suffering as symptoms are fully reversible after tumor resection.