The Importance of Molecular Imaging Characteristics for the Diagnosis and Management of Tumor-induced Osteomalacia

Objective: Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome associated with the overproduction of fibroblast growth factor 23 secondary to phosphaturic mesenchymal tumors (PMT). Our goal was to describe the morphometabolic characterization and histopathological correlation of images obtained from patients with suspected TIO using gallium-68 (68Ga) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate(68Ga‑DOTATATE) positron emission tomography/computed tomography (PET/CT) in a referral center in Argentina. Methods: A prospective, descriptive study with patients suspected of TIO who were referred to confirm the presence of primary lesions by 68Ga-DOTATATE PET/CT. Results: Eighteen patients were included (female: 72.22%; median age: 47.5 years [range: 41.5–54]). The median maximum standardized uptake value (SUVmax) was 17.2 (interquartile range: 6.27–30.6). Lesions diagnosed by 68Ga-DOTATATE PET/CT were predominantly localized in the appendicular skeleton. Most patients had one identifiable lesion. Lesions were focal and well-limited in 66.67% of cases. Histopathological data were available for 13 patients. PMT was diagnosed in 61.54% of cases; in this subgroup, 25% had lesions showing ill-defined borders and confirmed bone erosion. A numerically, non-significant higher SUVmax was found in patients with PMT. Also, a trend towards isolated soft tissue involvement was more commonly observed among these patients. Conclusion: In our patients with suspected TIO evaluated by 68Ga-DOTATATE PET/CT, a greater number of lesions were unique, well-defined, and localized in the appendicular skeleton. Nevertheless, ill-defined borders, including bone erosion, were reported in 25% of patients with confirmed PMTs. 68GaDOTATATE PET/CT is a valuable diagnostic tool for patients with suspected TIO. Further research is warranted.