Abstract
BackgroundTumor-induced osteomalacia (TIO) is a rare, acquired disease of renal phosphate wasting and disturbed vitamin D homeostasis as a result of the action of a phosphaturic protein – FGF-23, produced by a neoplasm. Although the clinical and biochemical profile of the syndrome is characteristic, it remains underreported and unrecognized by clinicians. Hyperparathyroidism is rarely associated with oncogenic osteomalacia, but it should be considered because of potentially life-threatening hypophosphatemia caused by both conditions.Case presentationWe report a case of a 42-year-old woman admitted to the Department of Otolaryngology of the Military Institute of Medicine in Warsaw for the endoscopic resection of hormonally active glomangiopericytoma extending into the anterior skull base. She presented with a 5-year history of musculoskeletal pain and progressive weakness of the extremities which finally led her to become bedridden. After the excision of the tumor her symptoms and laboratory results gradually improved except increasing PTH serum levels. Further examination revealed a parathyroid proliferative tumor, which was surgically removed. The patient walked without aids at follow-up 16 months after the surgery.ConclusionsThis case is unusual because of tumor-induced osteomalacia and parathyroid adenoma occurring concomitantly. Further investigations of FGF-23 and PTH interplay should be conducted to elucidate the pathogenesis of hyperparathyroidism and tumorigenesis in some cases of TIO. By presenting this case, we wanted to remind clinicians of a rare and misdiagnosed paraneoplastic syndrome and highlight the importance of monitoring PTH concentrations during the follow-up of patients with TIO.
Highlights
Tumor-induced osteomalacia (TIO) is a rare, acquired disease of renal phosphate wasting and disturbed vitamin D homeostasis as a result of the action of a phosphaturic protein – fibroblast growth factor (FGF)-23, produced by a neoplasm
Tumor-induced osteomalacia (TIO), known as oncogenic osteomalacia (OOM), is a rare paraneoplastic syndrome resulting from impaired phosphate and vitamin D metabolism and caused by tumors secreting fibroblast growth factor 23 (FGF-23)
We report a case of a woman with a metabolically active sinonasal glomangiopericytoma causing advanced TIO, with concurrent hyperparathyroidism in the course of parathyroid adenoma, and her clinical and laboratory response to surgical treatment
Summary
TIO is an uncommon and acquired paraneoplastic condition developing due to the production of phosphaturic factor by the neoplasm, leading to impaired phosphate and vitamin D metabolism. The uniqueness of the presented case is the very rare coexistence of tumorinduced osteomalacia and parathyroid adenoma, most likely being a consequence of tertiary hyperparathyroidism. Further investigations of FGF-23 and PTH interplay should be conducted to elucidate the pathogenesis of hyperparathyroidism and tumorigenesis in some cases of TIO. By presenting this case, we wanted to highlight the importance of monitoring PTH concentrations in patients with TIO, as there is a possibility of masked hyperparathyroidism
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