Correspondence

Radiofrequency Ablation of a Tumor Causing Oncogenic Osteomalacia

N Engl J Med 2007; 357:422-424July 26, 2007

Article

To the Editor:

Oncogenic osteomalacia is a rare syndrome that is usually driven by small, mesenchymal tumors that express phosphatonins, proteins that decrease the abundance of sodium–phosphate cotransporters in the proximal renal tubule. This decrease causes renal phosphate wasting and leads to the clinical features of oncogenic osteomalacia, which include hyperphosphaturia, hypophosphatemia, reduced or abnormal serum 1,25-dihydroxyvitamin D levels, and osteomalacia.1,2

The standard treatment of oncogenic osteomalacia is surgical excision of the mesenchymal tumor, which rapidly and permanently abrogates all symptoms. However, tumor removal can be complicated, because the lesion is usually small and difficult to distinguish from the surrounding tissue. Complete excision is necessary, because the syndrome typically persists if any tumor tissue remains. To ensure complete excision, surgery may require wide resection margins, causing iatrogenic tissue damage that is disproportional to the tumor, which is small and benign in most cases.

We present the case of a 40-year-old woman with an acquired hypophosphatemic, vitamin D–resistant osteomalacia due to a tumor in the right femoral head that was detected on coregistration of positron-emission tomography and computed tomography (known as PET–CT).3 Laboratory analyses revealed hypophosphatemia (serum phosphate level, 0.45 mmol per liter; normal range, 0.83 to 1.67) and a reduced renal tubular maximum for the reabsorption of phosphate normalized to the glomerular filtration rate (0.2 mmol per liter; normal range, 0.8 to 1.4). In our patient, complete tumor removal by means of an open surgical procedure would have required total hip arthroplasty. Because of her age, we attempted to preserve the healthy hip joint, which was not affected by the tumor. Multiple tissue samples were obtained with the use of needle biopsy guided by CT. Histologic analysis revealed a benign mesenchymal tumor, confirming the diagnosis. We performed CT-guided radiofrequency ablation to destroy the lesion, thereby avoiding arthroplasty. Complete tumor ablation was achieved 6 days later, after a second round of radiofrequency ablation, and was confirmed on the following day by magnetic resonance imaging (MRI) (Figure 1Figure 1MRI and CT Scans of the Tumor before, during, and after Radiofrequency Ablation.). A few weeks later, levels of biochemical markers returned to normal, and all symptoms resolved. Clinical follow-up at 1 year was unremarkable.

Radiofrequency ablation is a well-established procedure for selectively removing small volumes of tissue and is an effective palliative treatment for skeletal metastases. Radiofrequency ablation of benign primary bone tumors is generally restricted to osteoid osteoma and is the standard of care in many centers.4,5

This case demonstrates that CT-guided radiofrequency ablation may be used to treat a tumor causing oncogenic osteomalacia. We believe that radiofrequency ablation may broaden the scope of treatment options for oncogenic osteomalacia and may offer an effective, less invasive alternative to classic surgery.

Eric Hesse, M.D.
Yale University School of Medicine, New Haven, CT 06520-8044
eric.hesse@yale.edu

Herbert Rosenthal, M.D.
Hannover Medical School, 30625 Hannover, Germany

Leonard Bastian, M.D.
Klinikum Leverkusen, 51375 Leverkusen, Germany

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Citing Articles (9)

Citing Articles

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   Bergwitz, Clemens, Collins, Michael T., Kamath, Ravi S., Rosenberg, Andrew E., . (2011) Case 33-2011. New England Journal of Medicine 365:17, 1625-1635
   Full Text

2. 2

   Varsha S. Jagtap, Vijaya Sarathi, Anurag R. Lila, Gaurav Malhotra, Shilpa S. Sankhe, Tushar Bandgar, Padmavathy Menon, Nalini S. Shah. (2011) Tumor-Induced Osteomalacia: A Single Center Experience. Endocrine Practice 17:2, 177-184
   CrossRef

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   Steven W. Ing, O. Hans Iwenofu, Joel L. Mayerson, Nathan C. Hall. (2010) Tumor-induced Osteomalacia Localization by Whole-body Sestamibi Scan. The Endocrinologist 20:6, 267-270
   CrossRef

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   P. A. Daolio, S. Bastoni, M. Ferraro, F. Lazzaro, P. Zacconi, R. Zorzi, S. Mapelli, S. Casari, M. Laccisaglia. (2010) Fratture patologiche in paziente con tumore mesenchimale fosfaturico. Archivio di Ortopedia e Reumatologia 121:2-3, 32-33
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   Hakan Ilaslan, Jean Schils, Michael Joyce, Kenneth Marks, Murali Sundaram. (2010) Radiofrequency ablation: another treatment option for local control of desmoid tumors. Skeletal Radiology 39:2, 169-173
   CrossRef

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   M Odette Gore, Brian J Welch, Weidong Geng, Wareef Kabbani, Naim M Maalouf, Joseph E Zerwekh, Orson W Moe, Khashayar Sakhaee. (2009) Renal phosphate wasting due to tumor-induced osteomalacia: a frequently delayed diagnosis. Kidney International 76:3, 342-347
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   Harald JÜppner, Anthony A. Portale. 2009. Endocrine Regulation of Phosphate Homeostasis. , 105-126.
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   Michèle Duet, Samar Kerkeni, Raja Sfar, Cécile Bazille, Frédéric Lioté, Philippe Orcel. (2008) Clinical Impact of Somatostatin Receptor Scintigraphy in the Management of Tumor-induced Osteomalacia. Clinical Nuclear Medicine 33:11, 752-756
   CrossRef

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   Christian Falck, Thomas Rodt, Herbert Rosenthal, Florian Länger, Thomas Goesling, Wolfram H. Knapp, Michael Galanski. (2008) 68Ga-DOTANOC PET/CT for the detection of a mesenchymal tumor causing oncogenic osteomalacia. European Journal of Nuclear Medicine and Molecular Imaging 35:5, 1034-1034
   CrossRef