A neuroendocrine cause of oncogenic osteomalacia

In our case, a 45-year-old male patient had multiple fractures accompanied by hypophosphatemia. FGF-23 levels were significantly increased, and total body magnetic resonance imaging (MRI) revealed a tumor mass located at the distal tibia leading to the diagnosis of tumor-induced osteomalacia (TIO). After resection of the tumor, hypophosphatemia and the increased levels of FGF-23 normalized within a few days. Subsequent microscopic examination and immunohistochemical analysis revealed a phosphaturic mesenchymal tumor mixed connective tissue variant (PMTMCT) showing a positive expression of somatostatin receptor 2A (SSTR2A), CD68, and Periostin. Electron microscopy demonstrated a poorly differentiated mesenchymal tumor with a multifocal giant cell component and evidence of neurosecretory-granules. However, the resected margins showed no tumor-free tissue, and therefore a subsequent postoperative radiotherapy was performed. The patient is still in complete remission after 34 months. Tumor resection of PMTMCTs is the therapy of choice. Subsequent radiotherapy in case of incompletely resected tumors can be an important option to avoid recurrence or metastasis even though this occurs rarely. The prognostic value of expression of Periostin has to be evaluated more precisely in a larger series of patients with TIO.

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“…These findings are consistent with the majority of the literature [29–31]. However, some PMTs do not show neurosecretory granules [32].…”

Section: Discussionsupporting

confidence: 92%

“…In terms of ultrastructural features, neurosecretory granules were found similar to a neuroendocrine tumor [9, 29–31]. However, in these studies immunostaining for typical markers of neurosecretory tumors was negative.…”

Section: Discussionmentioning

confidence: 99%

Tumor-Induced Osteomalacia: Increased Level of FGF-23 in a Patient with a Phosphaturic Mesenchymal Tumor at the Tibia Expressing Periostin

Hautmann

Schroeder

Wild

et al. 2014

Case Reports in Endocrinology

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“…All cases, including ours, involved surgical intervention as a part of therapy. Chemo- and/or radiotherapy were used in less than half of spinal TIO cases [4, 6–8, 11]. In the present case, resection of tumor with spondylectomy using anterior retroperitoneal approach and L-4 corpectomy was curative.…”

Section: Discussionmentioning

confidence: 69%

“…The tumors responsible for TIO can be found anywhere in the body; however, only 11 prior cases have been described in the spine (Table 1) [4–14]. Only three spinal TIO cases, including ours, utilized RT-PCR to identify tissue expression of FGF-23 [10, 13].…”

Section: Discussionmentioning

confidence: 99%

Tumor-Induced Osteomalacia Caused by Primary Fibroblast Growth Factor 23 Secreting Neoplasm in Axial Skeleton: A Case Report

Gandhi

Shah

et al. 2012

Case Reports in Endocrinology

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We report the case of a 66-year-old woman with tumor-induced osteomalacia (TIO) caused by fibroblast growth factor 23 (FGF-23) secreting mesenchymal tumor localized in a lumbar vertebra and review other cases localized to the axial skeleton. She presented with nontraumatic low back pain and spontaneous bilateral femur fractures. Laboratory testing was remarkable for low serum phosphorus, phosphaturia, and significantly elevated serum FGF-23 level. Magnetic resonance imaging (MRI) of the lumbar spine showed a focal lesion in the L-4 vertebra which was hypermetabolic on positron emission tomography (PET) scan. A computed tomography (CT) guided needle biopsy showed a low grade spindle cell neoplasm with positive FGF-23 mRNA expression by reverse transcriptase polymerase chain reaction (RT-PCR), confirming the diagnosis of a phosphaturic mesenchymal tumor mixed connective tissue variant (PMTMCT). The patient elected to have surgery involving anterior resection of L-4 vertebra with subsequent normalization of serum phosphorus. Including the present case, we identified 12 cases of neoplasms localized to spine causing TIO. To our knowledge, this paper represents the first documented case of lumbar vertebra PMT causing TIO. TIO is a rare metabolic bone disorder that carries a favorable prognosis. When a lesion is identifiable, surgical intervention is typically curative.

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“…The rare literature reports show different histological types of mesenchymal tumours associated with paraneoplastic syndrome 12,13,15,21,23 . These are frequently tumours derived from vascular tissue (haemangiopericytomas) or bone (osteoblastoma-like tumours, non-ossifying fibroma-like tumours, ossifying fibroma-like tumours).…”

Section: Nonementioning

confidence: 99%