Selective venous catheterization for the localization of phosphaturic mesenchymal tumors

Abstract

Tumor-induced osteomalacia (TIO) is characterized by renal phosphate wasting, hypophosphatemia, and aberrant vitamin D3 metabolism and is caused by fibroblast growth factor 23 (FGF-23)–producing mesenchymal tumors, which are often difficult to locate. We investigated the utility of selective venous sampling in tumor localization. The primary endpoint was identification of the FGF-23 concentration ratio between the venous drainage of the tumor bed and the general circulation that was diagnostic of the location of an FGF-23-secreting tumor. Fourteen subjects underwent 15 sampling procedures after functional and anatomic imaging studies. Subjects fit into three imaging categories: no suspicious site, multiple sites, and single site (positive controls). FGF-23 levels were measured by ELISA. Suspicious tumors were resected for diagnosis, confirmation, and cure. In subjects with a positive venous sampling study and subsequent cure, a minimum ratio of 1.6 was diagnostic. In 7 of 14 subjects there was suggestive imaging, a diagnostic ratio, and an associated TIO tumor (true positive). Four of these required complicated resection procedures. In 4 of 14 subjects with no suspicious site on imaging studies, an FGF-23 diagnostic ratio was not detected (true negative). Biopsy or resection of a single lesion in 2 of 14 subjects with a diagnostic ratio failed to identify a TIO tumor (false positive). A diagnostic FGF-23 ratio was absent in 1 of 14 subjects whose tumor was a single highly suspicious lesion on imaging studies (false negative). These data yield a sensitivity of 0.87 [95% confidence interval (CI) 0.47–0.99] and a specificity of 0.71 (95% CI 0.29–0.96). Selective venous sampling for FGF-23 was particularly useful in subjects with multiple suspicious sites or an anatomically challenging planned resection but not in the absence of a suspicious lesion on imaging studies. © 2011 American Society for Bone and Mineral Research.

The diagnostic dilemma of tumor induced osteomalacia: a retrospective analysis of 144 cases

“…Currently, it is advocated performing a step-wise approach including functional imaging (octreotide scanning, 18F-FDG PET/CT and Ga-68 DOTATATE PET/CT), followed by anatomic imaging (radiography, ultrasound, CT and MRI). And if needed, selective venous sampling for FGF23 is usually successful in locating the tumors [8,26,27]. Chong WH and his colleague reported a series of 31 TIO subjects regarding tumor localization and proposed a systematic approach to localizing tumors in tumor induced osteomalacia [26].…”

Clinical practice

“…Tumours generally arise in the neck and head regions or in the skeleton and are usually described as mixed connective tissue tumours, haemangiopericytomas or chondroblastic-osteoblastic fibromas. Localisation of the tumour using octreotide scintigraphy is often successful; however, in certain situations, selective venous sampling for FGF23 concentrations may assist [3]. Removal of tumour after successful localisation results in resolution of symptoms, normalisation of phosphate within hours postoperatively and a decrease in FGF-23 levels.…”

Definitive surgical treatment of osteomalacia induced by skull base tumor and determination of the half-life of serum fibroblast growth factor 23

“…Intracranial FGF23-producing PMTMCT is extremely rare and, to the best of our knowledge, only 17 cases have been reported in the literature to date (Table 1) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. It tends to affect sterically complicated areas such as the anterior skull base.…”