S P E C I A L C l i n i c a l C a s e F E A T U R E S e m i n a r Radiofrequency Ablation, an Effective Modality of Treatment in Tumor-Induced Osteomalacia: A Case Series of Three Patients Swati Jadhav, Rajeev Kasaliwal, Nitin S. Shetty, Suyash Kulkarni, Krantikumar Rathod, Bhavesh Popat, Harshal Kakade, Amol Bukan, Shruti Khare, Sweta Budyal, Varsha S. Jagtap, Anurag R. Lila, Tushar Bandgar, and Nalini S. Shah rC DR Department of Endocrinology (S.J., R.K.), Seth G. S. Medical College and King Edward Memorial Hospital, Parel, Mumbai, 400012, India; Department of Radiodiagnosis (N.S.She., S.Ku.), Tata Memorial Centre, Parel, Mumbai 400012, India; and Departments of Radiology (K.R., B.P.) and Endocrinology (H.K., A.B., S.Kh., S.B., V.S.J., A.R.L., T.B., N.S.Sha.), Seth G. S. Medical College and King Edward Memorial Hospital, Parel, Mumbai, 400012, India po Context: Tumor-induced osteomalacia is curable if the tumors can be totally excised. However, when the tumors are present in locations that make surgery disproportionately risky, the need for less invasive strategies like radiofrequency ablation (RFA) is realized. or iza da Patients and Methods: We describe three patients with suspected tumor-induced osteomalacia who were treated in our department between 2006 and 2013 with tumors in surgically difficult locations and were subjected to single or multiple sessions of RFA. The response was documented in terms of symptomatic improvement, phosphorus normalization, and follow-up 99mTechnitiumlabelled hydrazinonicotinyl-Tyr3-octreotide (99mTc HYNIC TOC) scan. Co pi aa ut Results: Two of the three individuals, patient A (with a 1.5 ⫻ 1.2-cm lesion in the head of the right femur) and patient B (with a 1.3 ⫻ 1.2-cm lesion on the endosteal surface of the shaft of the left femur), achieved complete remission with single sessions of RFA. Three months after the procedure, 99mTc HYNIC TOC scans revealed the absence of uptake at the previous sites, corroborating with the clinical improvement and phosphorus normalization. Patient C had a large 5.6 ⫻ 6.5-cm complex lesion in the lower end of the left femur with irregular margins, loculations, and bone grafts placed in previous surgery. He failed to achieve remission after multiple sessions of RFA due to the complex nature of the lesion, although the tumor burden was reduced significantly as documented on serial 99mTc HYNIC TOC scans. Conclusions: Although surgery remains the treatment of choice, RFA could be an effective, less invasive, and safe modality of treatment in judiciously selected patients. (J Clin Endocrinol Metab 99: 3049 –3054, 2014) umor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome associated with predominantly benign tumors of mesenchymal origin. Less than 400 cases have been reported to date (1). It is a syndrome of acquired hypophosphatemic osteomalacia caused by “phosphatonins” like fibroblast growth factor (FGF) 23 (the most T well characterized), FGF7, secreted frizzle-related protein 4, and matrix extracellular protein (2, 3). Histopathologically, the tumors associated with TIO are classified as phosphaturic mesenchymal tumors (PMTs), the most common of which is the PMT mixed connective tissue variant, and others being PMT osteoblas- ISSN Print 0021-972X ISSN Online 1945-7197 Printed in U.S.A. Copyright © 2014 by the Endocrine Society Received December 25, 2013. Accepted June 6, 2014. First Published Online June 24, 2014 Abbreviations: CT, computed tomography; FGF, fibroblast growth factor; MRI, magnetic resonance imaging; PMT, phosphaturic mesenchymal tumor; RFA, radiofrequency ablation; SPECT, single photon emission CT; 99mTc HYNIC TOC, 99mTechnitium-labelled hydrazinonicotinyl-Tyr3-octreotide; TIO, tumor-induced osteomalacia; TMP/GFR, tubular maximum for phosphate corrected for glomerular filtration rate. doi: 10.1210/jc.2013-4515 J Clin Endocrinol Metab, September 2014, 99(9):3049 –3054 jcem.endojournals.org 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved. 3049 RFA in Tumor-Induced Osteomalacia J Clin Endocrinol Metab, September 2014, 99(9):3049 –3054 99m Tc HYNIC TOC scan Whole body planar acquisition was done 4 hours after iv injection of 15 mCi of 99mTc-HYNIC-TOC, followed by regional single photon emission CT (SPECT)/CT (Infinia Hawkeye; GE Healthcare). SPECT data were acquired in a 128 ⫻ 128 matrix through 360° rotation with 64 projections with an acquisition time of 20 seconds per projection in a step-and-shoot mode, with low-dose CT used for attenuation correction and anatomic characterization. Anatomical imaging Anatomical characterization of the lesions was done using CT or MRI scans. CT scans were obtained on a 64-slice Philips Brilliance CT scanner (Philips Healthcare), whereas MRI scans were performed on a 1.5 T Siemens Sonata MR scanner (Siemens Medical Solutions, Inc). DR Radiofrequency ablation rC After the procedure was explained to the patients and their informed consent was obtained, RFA was performed under general anesthesia. A multislice CT scanner machine was used, with the regional scan limited to the area of lesion using low radiation protocol (75 mA, 120 kV) to reduce the radiation exposure. An 11-gauge bone biopsy needle (Cook Medical) was used to enter the lesions using all aseptic precautions, and biopsy of the lesions was performed before ablation. All of the lesions were entered manually without the need of a drill. RFA was performed using multi-tined monopolar electrodes (RITA Medical Systems Inc, AngioDynamics), and ablation was performed for an adequate time (5–10 min), depending on the size of the lesion, with a target temperature of 90°C. Overlapping ablations were done to achieve complete ablation. Particular care was taken if the part of the lesion was adjacent to the joint surface or articular cartilage. Postprocedure physiotherapy was recommended for all patients. Patients who had lesions in weight-bearing areas were advised to rest and to refrain from carrying weights for 3 weeks. RFA was repeated after 1 month for the larger lesions in which residue was expected (patient C). iza toma-like variant, ossifying fibroma-like variant, and non-ossifying fibroma-like variant (4). Rare associations with malignant neoplasms like prostatic carcinoma and renal cell carcinoma have also been reported (5, 6). The localization of these tumors is often challenging because they can be present anywhere from the head to the toes, in soft tissues as well as in the bones, and are often small in size. Hence, the best strategy to localize them is to do functional imaging (with somatostatin receptor-based scans) first, followed by targeted anatomical imaging (computed tomography [CT] or magnetic resonance imaging [MRI]) (7). The patients with TIO can be cured completely if the tumor is properly localized and completely excised. Although surgery remains the treatment of choice, these tumors are often in difficult locations, deep in the bones or close to joints. In such circumstances, surgery might endanger the adjacent joints, or disproportionate tissue injury might occur in an attempt to access the tumor. These are the cases where less invasive modalities of treatment like radiofrequency ablation (RFA) are required. We describe our experience with RFA in three TIO patients with tumors in such difficult locations. po Jadhav et al da 3050 or Patients and Methods Co pi aa ut We describe three patients with suspected TIO who were treated in our department between 2006 and 2013 and were offered single or multiple sessions of RFA as a modality of treatment for various reasons (as described later). The details of clinical history, physical examination, biochemistry, functional imaging, anatomical characterization, and follow-up for clinical outcome were reviewed for each patient. The diagnosis of TIO was presumed based on clinical features, biochemical profile, imaging characteristics, and the response to treatment. Bone biopsy was not performed in any of the patients. Biochemical assays Routine biochemical evaluation included serum calcium, phosphorus, alkaline phosphatase, creatinine, albumin, 25hydroxyvitamin D, 1,25-dihydroxyvitamin D, PTH, tubular maximum for phosphate corrected for glomerular filtration rate (TMP/GFR), and FGF23. Tubular resorption of phosphate was measured from spot fasting urine and serum phosphorus and creatinine at baseline, and TMP/GFR was calculated with the use of a nomogram reported by Bijvoet et al (8). FGF23 was assessed by ELISA (FGF23 [C-terminal] kit; Immunotopics, Inc). The kit has a sensitivity of 3.0 RU/mL and intra-assay and interassay coefficients of variation of 5 and 7.3%, respectively. Functional imaging Each of the three patients was subjected to functional imaging with a 99mTechnitium-labelled hydrazinonicotinyl-Tyr3-octreotide (99mTc HYNIC TOC) scan. Results The baseline characteristics of the patients are given in Table 1. Patient A was a 38-year-old man who presented with a 6-year history of low backache, diffuse bony pains, and proximal muscle weakness gradually progressing to the extent that he had difficulty in performing daily activities. There was evidence on x-rays of osteomalacia with multiple pseudofractures. On evaluation, patient A was found to have hypophosphatemia with renal phosphate wasting and a high normal FGF23, which was inappropriate for low phosphorus. For a diagnosis of oncogenic hypophosphatemic osteomalacia, a 99mTc HYNIC TOC scan was performed, and the lesion was found to be localized to the tumor in the head of right femur. A corresponding contrast-enhancing lesion was 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved. doi: 10.1210/jc.2013-4515 3051 Baseline Characteristics: Symptoms, Biochemistry, Imaging, and Follow-Up Size of the lesion, cm Tc HYNIC TOC Anatomical imaging (CT/MRI) Histopathology Duration of follow-up after RFA, mo 38 M 6 LBP, PMW, LP 9.6 1.2 3.5 243 110 24 10.2 30 1.25 47.9 28 F 8 LBP, PMW, LP 8.4 1.4 2.6 207 55 27.7 9.39 35 0.68 54.1 49 M 17 LBP, PMW, LP, FR 8.1 1 2.03 261 198 30.3 19.6 0.25 45.5 144.9 23 162.4 41 6000 5500 Head of right femur Endosteal surface of proximal shaft of left femur 1.3 ⫻ 1.2 Positive CT and MRI NA 15 DR Patient C 1.5 ⫻ 1.2 Positive MRI NA 12 Lower end of left femur 5.6 ⫻ 6.5 Positive CT Non-ossifying fibroma 6 da 99m Patient B rC Age, y Sex Duration of symptoms, y Symptoms Calcium, mg/dL (9 –11) Phosphorus, mg/dL (2.5– 4.5) Post RFA (day 7) Alkaline phosphatase, U/L (20 –140) Post RFA (6 months) 25-hydroxyvitamin D, ng/mL (20 –70) 1,25-dihydroxyvitamin D, pg/mL (19.6 –54.6) Post RFA (6 mo) TMP/GFR PTH, pg/mL (15– 65) FGF23, RU/mL (0 –150) Pre RFA Post RFA (d 7) Localization Site of the lesion Patient A po Table 1. jcem.endojournals.org iza Abbreviations: M, male; F, female; LBP, low back pain; PMW, proximal muscle weakness; LP, limbs pain; FR, fractures; NA, not available. Normal range is given in parentheses. to the endosteal surface of the proximal shaft of the left femur, suggesting a diagnosis of TIO. In her case as well, it was anticipated that accessing the lesion via open surgery would lead to disproportionate tissue dissection, and hence she was offered a single session of RFA after discussion with orthopedic surgeons and the interventional radiology teams. The biopsy of the lesion Co pi aa ut or found on MRI scan. Owing to the location of the tumor, it was felt that accessing the tumor surgically would involve the probability of a breach of the hip joint. Hence, after discussion with the orthopedic surgeons and the interventional radiology team, the patient was offered a single session of RFA. The biopsy of the lesion was performed before ablation. However, it revealed only scanty fibrocartilaginous tissue, insufficient for opinion. The MRI scan performed 7 days after RFA confirmed complete ablation of the lesion, but there were postinflammatory changes. The phosphorus returned to normal (3.5 mg/dL) when evaluated 7 days after the RFA, and FGF23 decreased further from the baseline value (Table 1). His symptoms resolved completely within 3 months, and he resumed his job. Three months after RFA, a repeat functional scan with 99mTc HYNIC TOC showed an absence of uptake in the femoral lesion, further corroborating complete remission (Figure 1). Patient B was a 29-year-old woman, a homemaker who had been incapacitated by low back ache, proximal muscle weakness, and diffuse lower limb pain of 8-year duration. Skeletal survey revealed multiple pseudofractures suggesting osteomalacia. She had hypophosphatemia with inappropriately elevated FGF23 (Table 1). Considering a diagnosis of TIO, a 99mTc HYNIC TOC scan was performed, and the lesion was localized Figure 1. Patient A. A, 99mTc HYNIC TOC SPECT CT scan showing uptake in the head of right femur. B, Post contrast T1W fat-saturated sequence of MRI showing enhancing lesion in the same area. C, RFA needle in situ. D, Three months after RFA, 99mTc HYNIC TOC SPECT/CT scan showing the absence of uptake in the same area. 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved. 3052 Jadhav et al RFA in Tumor-Induced Osteomalacia J Clin Endocrinol Metab, September 2014, 99(9):3049 –3054 Figure 3. Patient C. A, CT scan showing tumor in the lower end of left femur. Long arrow shows the bone graft in place, and smaller arrows show the irregular margins and loculations. B and C, RFA needle placement during first and second sessions, respectively. D, Before RFA, 99mTc HYNIC TOC SPECT/CT scan showing diffuse uptake throughout the lesion. E and F, Sequential reduction in the uptake on 99m Tc HYNIC TOC SPECT/CT scan after first and fourth RFAs, respectively. rC po da be achieved after multiple sessions of RFA, and phosphorus as well as FGF23 failed to normalize. Discussion Co pi aa ut or iza performed before ablation yielded fibrocartilaginous tissue insufficient for any opinion. A MRI scan performed 3 days after RFA revealed no residual lesion, but there were postinflammatory changes. Seven days after RFA, her phosphorus and FGF23 had normalized (2.6 mg/dL and 41 RU/mL, respectively). She had complete resolution of symptoms within 3 months, and she could resume all of her previous activities. The 99mTc HYNIC TOC scan performed 3 months later demonstrated an absence of uptake in the previous site in the femur, thus underscoring complete remission (Figure 2). Patient C was a 48-year-old man who had a longstanding history of low backache and diffuse lower limb pain of 17-years duration. He had hypophosphatemia, multiple pseudofractures on x-rays, and an elevated FGF23. He was presumed to have hypophosphatemic osteomalacia and was on long-term phosphorus supplements. The lesion was localized to the lower end of the right femur when he presented with a pathological fracture. He underwent his first surgery in 2006, when bone curettage and grafting were done. However, complete excision could not be achieved due to the extensive nature of the lesion, and he continued to be on medical management. In 2013, after a joint consultation, he was offered RFA as an alternative mode of therapy because repeat surgery would have involved a high risk of amputation of the lower limb. Owing to the large and complex nature of the lesion with irregular margins and bone grafts in place, it was envisioned that he might require multiple sessions of RFA. After four sessions of RFA, the serial functional imaging with 99mTc HYNIC TOC scans revealed sequential reduction of uptake in the corresponding ablated areas, suggesting reduction in tumor load (Figure 3). However, remission could not DR Figure 2. Patient B. A and B, 99mTc HYNIC TOC SPECT/CT scans showing uptake in shaft of left femur. C, CT scan showing the lesion in the same area. D, RFA needle in situ. E and F, Three months after RFA, the absence of uptake on 99mTc HYNIC TOC SPECT/CT scan. TIO is a debilitating phosphate-wasting disorder caused by predominantly mesenchymal tumors producing phosphatonins like FGF23 and others. The intriguing feature of these tumors is that apart from the production of phosphaturic factors, they are otherwise largely benign, although rare associations with malignant tumors have also been reported (5, 6). These tumors require complete excision for cure of the underlying condition. However, as described above, these tumors are often present in difficult locations where the need for less invasive modality is realized. In our experience, RFA can be a useful modality for such situations. RFA was first described for the treatment of hepatic tumors in 1990 (9). Since then, its use has found wider application in the management of various tumors. It is based on the principle of achieving thermal ablation of the tissue by use of alternating electric current that operates in the range of 200 –1200 kHz. As the alternating electric current passes through the tissue, ions in the tissue attempt to follow the alternating direction of the current, frictional heat is generated that ablates the tissue in the vicinity of the electrode, and the conduction of heat causes farther tissue ablation (9). In the management of bone tumors like osteoid osteoma, RFA is now the preferred modality of treatment because it is associated with significantly less duration of hospital- 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved. doi: 10.1210/jc.2013-4515 jcem.endojournals.org phosphorus normalization, and the disappearance of uptake on functional imaging (99mTc HYNIC TOC scans). To the best of our knowledge, this is the first study to corroborate remission with functional imaging. One of the limitations of our study was that the biopsies performed before ablation in patients A and B could not yield sufficient tissue to give any conclusive opinion. However, in the absence of histopathology, the clinical and biochemical improvement after ablation provided convincing corroborative evidence to suggest that the targeted lesions were the causative ones. po rC DR Conclusions Although surgery remains the treatment of choice, RFA could be an effective, less invasive, and safe modality of treatment in patients with TIO having tumors in surgically difficult to access locations. The smaller size of the lesion, well-delineated margins, and expertise of the RFA team are the important determinants for a successful outcome of RFA in these patients. Hence, judicious selection of patients for RFA is important for the success of the procedure. da ization, no major complications, and a rapid convalescence (10, 11). The literature regarding the use of RFA as a treatment modality in TIO is scarce. To the best of our knowledge, there has been a singular case report where Hesse et al (12) subjected a 40-year-old woman with a lesion in the head of the femur to two sessions of RFA, resulting in remission that was demonstrated clinically, biochemically, and on MRI. The decision to use RFA in this patient was made to avert the risk of total hip arthroplasty. The use of a less invasive modality for the treatment of TIO was also described by Tutton et al (13) when they successfully treated a 51-year-old male patient with TIO, who had a tumor in the right iliac bone, with CT-guided percutaneous ethanol ablation and cryoablation. In our series, two patients (patients A and B) achieved complete remission after a single session of RFA, whereas patient C continued to have persistent disease after four sessions. The failure of RFA in patient C might be attributed to several factors. The lesion in patient C was much larger in size than the other two patients (Table 1). Size of the lesion is one of the important determinants for the success of RFA. It has been shown in patients with liver metastasis from colorectal cancers that the rate of recurrence after RFA increases with the increasing size of lesions, reflecting the difficulty in achieving complete ablation in larger tumors (14). In addition, patients A and B had tumors with well-delineated margins, whereas patient C had a lesion with irregular margins and loculations due to bone grafts placed during previous surgery. These factors precluded accurate placement of a needle and achievement of uniform and complete ablation. The secretory nature of the tumors associated with TIO makes the achievement of complete ablation particularly important. Hence, although the tumor burden was significantly reduced in patient C, as documented on serial 99mTc HYNIC TOC scans, FGF23 failed to normalize due to the persistent secretion from a small remnant that was inaccessible for ablation. Even with surgery, which is the preferred first line of treatment for TIO, resection with wide margins is necessary for ensuring remission (7). Extending the same principle to RFA, the importance of achieving complete ablation, including a rim of perilesional normal tissue, for achieving remission cannot be over emphasized. There were no reported side effects of the procedure, and the patients could be discharged within 24 hours of hospitalization. In our series, we attempted to demonstrate remission by multiple congruent parameters, ie, clinical improvement, 3053 Co pi aa ut or iza Acknowledgments Address all correspondence and requests for reprints to: Dr. Swati Jadhav, MBBS, MD, Senior Resident, Department of Endocrinology, Seth G. S. Medical College and King Edward Memorial Hospital, Parel, Mumbai. Maharashtra, 400012, India. E-mail: [email protected]. Disclosure Summary: The authors have no conflicts of interest to disclose. References 1. Jiang Y, Xia WB, Xing XP, et al. Tumor-induced osteomalacia: an important cause of adult-onset hypophosphatemic osteomalacia in China: report of 39 cases and review of the literature. J Bone Miner Res. 2012;27:1967–1975. 2. White KE, Larsson TE, Econs MJ. The roles of specific genes implicated as circulating factors involved in normal and disordered phosphate homeostasis: frizzled related protein-4, matrix extracellular phosphoglycoprotein, and fibroblast growth factor 23. Endocr Rev. 2006;27:221–241. 3. Habra MA, Jimenez C, Huang SC, et al. Expression analysis of fibroblast growth factor-23, matrix extracellular phosphoglycoprotein, secreted frizzled-related protein-4, and fibroblast growth factor-7: identification of fibroblast growth factor-23 and matrix extracellular phosphoglycoprotein as major factors involved in tumorinduced osteomalacia. Endocr Pract. 2008; 14:1108 –1114. 4. Weidner N, Santa Cruz D. Phosphaturic mesenchymal tumors. A polymorphous group causing osteomalacia or rickets. Cancer. 1987; 59:1442–1454. 5. Mak MP, da Costa e Silva VT, Martin RM, et al. Advanced prostate cancer as a cause of oncogenic osteomalacia: an underdiagnosed condition. Support Care Cancer. 2012;20:2195–2197. 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved. 3054 Jadhav et al RFA in Tumor-Induced Osteomalacia J Clin Endocrinol Metab, September 2014, 99(9):3049 –3054 6. Xie Y, Li HZ. Oncogenic osteomalacia caused by renal cell carcinoma. J Clin Endocrinol Metab. 2013;98:4597– 4598. 7. Chong WH, Molinolo AA, Chen CC, Collins MT. Tumor-induced osteomalacia. Endocr Relat Cancer. 2011;18:R53–R77. 8. Bijvoet OL, Morgan DB, Fourman P. The assessment of phosphate reabsorption. Clin Chim Acta. 1969;26:15–24. 9. Rhim H, Goldberg SN, Dodd GD 3rd, et al. Essential techniques for successful radio-frequency thermal ablation of malignant hepatic tumors. Radiographics. 2001;21:S17–S35. 10. Rehnitz C, Sprengel SD, Lehner B, et al. CT-guided radiofrequency ablation of osteoid osteoma and osteoblastoma: clinical success and long-term follow up in 77 patients. Eur J Radiol. 2012;81:3426 – 3434. Co pi aa ut or iza da po rC DR 11. Rosenthal DI, Hornicek FJ, Wolfe MW, Jennings LC, Gebhardt MC, Mankin HJ. Percutaneous radiofrequency coagulation of osteoid osteoma compared with operative treatment. J Bone Joint Surg Am. 1998;80:815– 821. 12. Hesse E, Rosenthal H, Bastian L. Radiofrequency ablation of a tumor causing oncogenic osteomalacia. N Engl J Med. 2007;357:422–424. 13. Tutton S, Olson E, King D, Shaker JL. Successful treatment of tumor-induced osteomalacia with CT-guided percutaneous ethanol and cryoablation. J Clin Endocrinol Metab. 2012;97:3421–3425. 14. Künzli BM, Abitabile P, Maurer CA. Radiofrequency ablation of liver tumors: actual limitations and potential solutions in the future. World J Hepatol. 2011;3:8 –14. 24/09/2014 The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 September 2014. at 13:50 For personal use only. No other uses without permission. . All rights reserved.
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