Oncogenic osteomalacia: case report and review of head and neck associated tumours

Intracranial Phosphaturic Mesenchymal Tumors: A Systematic Literature Review of a Rare Entity

BACKGROUND

Phosphaturic Mesenchymal Tumors (PMTs) are rare mesenchymal neoplasms known for producing Tumor-induced Osteomalacia (TIO). TIO is an uncommon paraneoplastic syndrome characterized by radiographic evidence of inadequate bone mineralization and analytical abnormalites.

METHODS

We sought to present a case of TIO caused by skull base PMT with intracranial extension, manifesting with pain, progressive weakness, and multiple bone fractures. Furthermore, a systematic review was performed, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. A search was conducted in PubMed database with title/abstract keywords "Phosphaturic mesenchymal tumor" and "Osteomalacia." Search results were reviewed looking for intracranial or skull base tumors.

RESULTS

Our systematic review included 29 reported cases of intracranial PMT. In the reviewed cases there was a significative female predominance with 22 cases (75,86%). Osteomalacia was presented in 25 cases (86,20%). Bone fractures were present in 10 cases (34,48%). The most common site of involvement was the anterior cranial fossa in 14 cases (48,27%). Surgery was performed in 27 cases (93,10%) with previous tumor embolization in 4 cases (13,79%). Total recovery of the presenting symptoms in the first year was achieved in 21 cases (72,41%). Recurrence of the disease was described in 6 cases (25%).

CONCLUSIONS

Skull base PMTs with intracranial extension are extremely rare tumors. Most patients are middle-aged adults with a PMT predominantly located in anterior cranial fossa. Surgery is the current treatment of choice with optimal outcome at 1-year follow-up, although recurrence could be present in almost 25% of the cases.

Sphenoid sinus is a rare site for tumor-induced osteomalacia: A case report and literature review

BACKGROUND

In this paper, we present a rare case of tumor-induced osteomalacia (TIO) and a literature review of this rare disease.

METHODS

A case of TIO of the isolated sphenoid sinus was reported. Furthermore, the clinical features of TIO in the sphenoid sinus and other sinonasal sinuses were also reviewed and summarized.

RESULTS

A 35-year-old man with muscle weakness and lower back pain came to the Department of Neurology. No obvious neurological disease was found; however, magnetic resonance imaging of the extremities accidentally showed a tumor in the axilla. Bone scintigraphy showed suspicious bone metastasis. Hypophosphatemia was neglected. Interestingly, 2-deoxy-2-[fluorine-18]fluoro-d-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) detected a tumor in the axilla and another in the sphenoid sinus, but only the tumor in the sphenoid sinus had somatostatin receptor (SSTR) expression in 68-gallium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid octreotate (Ga-68 DOTATATE) PET/CT. The sphenoid sinus tumor was proven to be a phosphaturic mesenchymal tumor (PMT), and the phosphate levels returned to normal after surgery. The literature review showed only 17 cases of TIOs that occurred in the sphenoid sinus, with an average age of 43.3 ± 13.7 years. Only three cases of TIOs in the sphenoid sinus did not invade the nasal cavity or other paranasal sinuses, which could be identified as isolated sphenoid sinus diseases. We compared the clinical features of sphenoid TIOs with those of non-sphenoid sinonasal TIOs, and it was found that the concentration of 1,25-dihydroxy vitamin D in the group with sphenoid TIOs was much higher than that in the group with non-sphenoid sinonasal TIOs. A total of 153 cases of TIOs in the sinonasal sinus were reviewed. The ethmoid sinus was found to be the major site (64.7%), followed by the nasal cavity (50.3%), maxillary sinus (19.0%), frontal sinus (16.4%), and sphenoid sinus (11.8%). There were 66 patients (43.1%) who showed tumors invading more than one sinus. Most of the tumors (69.3%) were diagnosed as PMTs by pathology, followed by hemangiopericytoma (14.3%). Immunostaining was beneficial in the differential diagnosis of these tumors; however, larger sample sizes are needed for better accuracy.

CONCLUSION

TIO in the sinonasal sinus, especially in the sphenoid sinus, is rare. Moreover, isolated sphenoid sinus disease can be easily misdiagnosed. When the clinical manifestation of osteomalacia is atypical, associating it with sphenoid sinus disease is even more difficult. Thus, TIO in the sphenoid sinus needs further exploration.

Intracranial phosphaturic mesenchymal tumors. A case report and review of literature

Most osteomalacia-inducing tumors (OITs) are phosphaturic mesenchymal tumors (PMTs) that secrete fibroblast growth factor 23 (FGF23). These tumors usually occur in the bone and soft tissues, and intracranial OITs are rare. Therefore, intracranial OIT is difficult to diagnose and treat. This paper presents a case of intracranial OIT and shows a review of previous cases. A 45-year-old man underwent nasal cavity biopsy and treatment with active vitamin D₃ and neutral phosphate for hypophosphatemia. Amplification of FGF23 mRNA level within the tumor was detected. Subsequently, the surgical specimen was diagnosed with a PMT and was considered the cause of the patient's osteomalacia. The patient was referred to a neurosurgery department for the excision of the intracranial tumor extending to the nasal cavity. After tumor removal, the serum levels of FGF23 and phosphorus were normalized as compared to preoperative those. The patient remains disease-free, without additional treatment, approximately 10 years after surgery, with no tumor recurrence. As per the literature, intracranial OITs usually occur in patients aged 8-69 years. Bone and muscle pain are major complaints. Approximately 60% of the patients reported previously had symptoms because of intracranial tumors. In some cases, it took several years to diagnose OIT after the onset of the osteomalacia symptoms. Laboratory data in such cases show hypophosphatemia and elevated FGF23 levels. Because FGF23 levels are associated with the severity of osteomalacia symptoms, total tumor resection is recommended. PMT and hemangiopericytoma (HPC) are histologically similar, but on immunochemistry, PMT is negative for signal transducer and activator of transcription 6 (STAT6), whereas HPC is positive. FGF23 amplification is seen in PMTs but not in HPCs. Therefore, the analysis of FGF23 and STAT6 was helpful in distinguishing PMTs from HPCs. In cases of hypophosphatemia and osteomalacia without a history of metabolic, renal, or malabsorptive diseases, the possibility of oncogenic osteomalacia should be considered.

Clinical, histopathologic, subtype, and immunohistochemical analysis of jaw phosphaturic mesenchymal tumors

Jaw phosphaturic mesenchymal tumors (PMTs) are a rare neoplasm with uncertain histogenesis. This study aimed to clarify the clinical and pathological features of jaw PMTs.We reviewed the clinical records of 39 patients diagnosed with PMTs in the jaws, and investigated clinical and morphologic characteristics, histologic subtypes, and immunophenotypes of all cases.Microscopic analyses revealed 2 major histologic tumor subtypes: "phosphaturic mesenchymal tumors of mixed epithelial and connective tissue" (PMTMECT), and "phosphaturic mesenchymal tumors of mixed connective tissue" (PMTMCT). PMTMECTs and PMTMCTs accounted for 29 and 10 cases of PMTs, respectively. Most PMTMECT diagnoses were made predominantly in males aged <45 years, and the incidence was similar in both the mandible and maxilla. In contrast, patients with PMTMCTs are predominantly females aged ≥45 years, and all tumors were in the mandible. Histologically, PMTMECT had lower cellularity and a more elongated and spindled mesenchymal component with less elaborate intrinsic microvasculature than PMTMCT. Immunohistochemically, the epithelia of all PMTMECTs was immunoreactive for AE1/AE3. Other immunohistochemical staining of PMTMECTs revealed positive expression of vimentin, SATB2, ERG, CD99, Bcl-2, CD56, S-100, D2-40, CD68, SMA, and CD34 in either one or both components. Immunohistochemical staining of PMTMCTs was diffusely positive for vimentin and a varied ratio of positivity for SATB2, ERG, CD99, Bcl-2, CD56, S-100, D2-40, CD68, SMA, and CD34, but negative for AE1/AE3. Most patients were cured by complete resection, except 2 patients who had repeated recurrences, one of which also had multiple metastasis.Jaw PMT can be divided into 2 major histological subtypes. PMTMECTs are more common than are PMTMCTs, and can transform into malignant PMTMCTs during the progression. PMTMECTs were more commonly observed in males and the incidence was similar in both the maxilla and mandible. PMTMCTs were almost always observed in the mandible of females. Compared with PMTMCTs, PMTMECTs have an admixture of epithelial components with less prominent vasculature and lower cellularity. There were no statistically significant differences in the expression of immunohistochemical markers except AE1/AE3 between PMTMECTs and PMTMCTs. However, immunohistochemical markers have great significance for differentiating other mesenchymal tumors.

Tumor induced osteomalacia in head and neck region: single center experience and systematic review

Tumor-induced osteomalacia in the head and neck region remains a challenging diagnosis to manage. Literature pertaining to management and outcome details remains sparse. We describe two cohorts: cohort 1 included seven patients from a single center in Western India with tumors located in paranasal sinuses (n = 3), intracranial (n = 2) and maxilla (n = 2). The unique features from our series is the management of persistent disease with radiation therapy (n = 2) and peptide receptor radionuclide therapy (PRRT) (n = 1). Cohort two has 163 patients identified from 109 publications for systematic review. Paranasal sinuses, mandible, intracranial disease, maxilla and oral cavity, in descending order, are reportedly common tumor sites. Within this cohort, mean age was 46 ± 14 years at presentation with 44.1% having local symptoms. Duration of symptoms varied from 1 to 240 months. Pre-surgery mean serum phosphorus was 1.4 ± 0.4 mg/dL and median FGF-23 levels were 3.6 (IQR:1.8-6.8) times of normal upper limit of normal. Majority (97.5%) were managed primarily with surgical excision; however, primary radiotherapy (n = 2) and surgery combined with radiotherapy (n = 2) were also reported. Twenty patients had persistent disease while nine patients had recurrence, more commonly noted with intracranial and oral cavity tumors. Surgery was the most common second mode of treatment employed succeeded by radiotherapy. Four patients had metastatic disease. The most common histopathological diagnosis reported is PMT mixed connective tissue, while the newer terminology 'PMT mixed epithelial and connective tissue type' has been described in 15 patients.

Phosphaturic Mesenchymal Tumors Involving Skull Bones: Report of Two Rare Cases

Phosphaturic mesenchymal tumor (PMT) is a rare tumor causing oncogenic osteomalacia (OO). Most such tumors occur in soft tissue and bones of extremities and appendicular skeleton. Intracranial location and involvement of temporal–occipital bone is extremely rare. We report two unusual cases: The first was intracranial, involving the temporal bone, while the other was a skull base tumor arising from the occipital–temporal bone. Both of them presented with paraneoplastic syndrome of OO, resembled a meningioma radiologically, and underwent gross total resection of tumor. Histologically, both of them were diagnosed as PMT, mixed connective tissue variant.

Phosphaturic mesenchymal tumor with an admixture of epithelial and mesenchymal elements in the jaws: clinicopathological and immunohistochemical analysis of 22 cases with literature review

Information on the heterogeneity of phosphaturic mesenchymal tumor, a rare entity associated with tumor-induced osteomalacia, is limited. In this retrospective analysis of 222 phosphaturic mesenchymal tumors, 22 cases exhibited mixed mesenchymal and epithelial elements, which we propose to term "phosphaturic mesenchymal tumor, mixed epithelial, and connective tissue type." Phosphaturic mesenchymal tumor of the mixed epithelial and connective tissue type showed a distinctive and significant male predominance (male:female = 2.67:1), with most patients diagnosed at <40 years old. Moreover, all tumors were mainly located in the alveolar bone with focal invasion into surrounding soft tissue and oral mucosa, which could be detected preoperatively by oral examination. The mesenchymal component, composed of spindled cells resembling fibroblasts or myofibroblasts arranged in a storiform or fascicular pattern, exhibited a less prominent vasculature and lower cellularity than the typical phosphaturic mesenchymal tumor (mixed connective tissue type). The epithelial component was typically haphazardly and diffusely distributed throughout the tumor, forming small, irregular nests resembling odontogenic epithelial nests. All cases were immunoreactive for fibroblast growth factor-23, somatostatin receptor 2A, and NSE in both components. Mostly also demonstrated positive staining for CD99 (21/22, 96%), CD56 (16/22, 73%), Bcl-2 (21/22, 96%), and D2-40 (19/22, 86%) in one or both components. S100 was positive in both components in one of seven cases. Interestingly, immunoreactivity was typically stronger and more diffuse in the epithelial than in the paired mesenchymal components. The mesenchymal component was also diffusely positive for CD68 (17/17, 100%) and showed variable focal staining for SMA (15/22, 68%) and CD34 (9/19, 47 %). These results indicate that phosphaturic mesenchymal tumor of the mixed epithelial and connective tissue type has distinctive clinicopathological characteristics and a polyimmunophenotypic profile.

Ethmoid tumor and oncogenic osteomalacia: Case report and review of the literature

INTRODUCTION

Oncogenic osteomalacia is a very rare disease usually caused by a phosphaturic mesenchymal tumor, particularly the "mixed connective tissue type", secreting FGF-23 hormone.

OBJECTIVE

The authors report a case of ethmoid tumor associated with oncogenic osteomalacia and discuss management based on a review of the literature.

CASE SUMMARY

A 41-year-old woman with multiple fractures causing major disability was diagnosed with early-onset osteoporosis. CT scan followed by MRI, performed due to the concomitant presence of nasal obstruction, showed a right ethmoid tumor in contact with the dura mater and periorbital tissues, but with no signs of invasion. Endoscopic resection was performed with reconstruction of the defect of the cribriform plate by a nasoseptal flap. Nasal and bone symptoms subsequently resolved. Histological examination revealed a phosphaturic mesenchymal tumor.

DISCUSSION

Twelve cases of mesenchymal tumor of the ethmoid sinus associated with oncogenic osteomalacia have been reported to date. FGF-23 assay and whole-body MRI with STIR sequence are useful for the diagnosis. A very favorable outcome is observed after surgical treatment in the majority of cases.

Anterior Skull Base Glomangioma-Induced Osteomalacia

Oncogenic osteomalacia (OO) is an uncommon but treatable cause of osteomalacia related to tumor production of FGF23, usually caused by benign mesenchymal neoplasms. Paranasal sinus glomangiomas are a rare cause of OO, with only one previously reported case. Here we describe a second case (first reported in English) of paranasal sinus glomangioma-induced osteomalacia in a 42-year-old man. He presented with weakness and multiple spontaneous fractures, and was found to have an ethmoid sinus glomangioma with intracranial extension. The tumor was removed via endoscopic endonasal approach to the anterior skull base, which resulted in complete resolution of symptoms and no further evidence of disease 1 year postoperatively.

Tumor-induced hypophosphatemia

Significant hypophosphatemia is commonly due to Vitamin D deficiency. Any sporadic onset of hypophosphatemia in adults warrants workup to identify alternate causes. Hypophosphatemia may also be the only manifestation of an occult malignancy. A high index of clinical suspicion can help diagnose such conditions in early stages. Prompt treatment of the cause can correct this biochemical abnormality. We describe a case report of a woman presenting with severe hypophosphatemia and osteomalacia, leading eventually to the diagnosis of a phosphaturic mesenchymal tumor of the temporo-occipital bone. Surgical resection of tumor led to normalization of the biochemical parameters as well as a complete clinical recovery.

Phosphaturic Mesenchymal Tumor: 2 New Oral Cases and Review of 53 Cases in the Head and Neck

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm that secretes fibroblast growth factor-23 (FGF-23) and causes oncogenic osteomalacia. It occurs in adults with equal gender distribution and the most common location is the lower extremities, followed by the head and neck. Besides osteomalacia, the clinical presentation includes bone pain and multiple bone fractures. Microscopic features consist of spindle cells, multinucleated giant cells, and calcifications embedded in a chondromyxoid matrix. Laboratory findings indicate normal calcium and parathyroid levels, hypophosphatemia, and increased levels of FGF-23 that usually revert to normal after surgical removal. Due to its rarity, the purpose of the study was to report 2 new oral cases of PMT and to review the literature in the head and neck. The first case occurred in the gingiva and had been present for 6 years. The second case was a recurrence of a previously diagnosed PMT in the right mandible that metastasized to the lung and soft tissue. The literature review included 53 cases in the head and neck. There was a predilection for extra-oral sites (76%) compared to intra-oral sites (24%) with paranasal sinuses considered the most common location (38%) followed by the mandible (15%). There were 9 recurrences that included 3 malignant cases indicating a potentially aggressive tumor. Due to the indeterminate biological behavior of PMT and its rarity, a comprehensive evaluation of medical, laboratory, radiographic, and histological findings are crucial for a definitive diagnosis and treatment.

Phosphaturic mesenchymal tumor of the brain without tumor-induced osteomalacia in an 8-year-old girl: case report

Phosphaturic mesenchymal tumor (mixed connective tissue variant) (PMT-MCT) are tumors that may cause tumor-induced osteomalacia and rarely appear intracranially. The authors describe the case of an 8-year-old girl who was found to have PMT-MCT with involvement of the cerebellar hemisphere and a small tumor pedicle breaching the dura mater and involving the skull. This was removed surgically in gross-total fashion without further complication. Histologically the tumor was confirmed to be a PMT-MCT. There was no evidence of tumor-induced osteomalacia. At the 42-month follow-up, the patient is doing well, has no abnormalities, and is free of recurrence. PMT-MCTs are rare tumors that may involve the brain parenchyma. A gross-total resection may be effective to cure these lesions.

Phosphaturic Mesenchymal Tumor Involving the Head and Neck: A Report of Five Cases with FGFR1 Fluorescence In Situ Hybridization Analysis

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm; however, it is the most common cause of tumor-induced osteomalacia (TIO), a paraneoplastic syndrome characterized by renal phosphate wasting and hypophosphatemia. A subset of PMTs harbours an FGFR1 translocation although this alteration has not been demonstrated in PMT involving a head and neck site. We present a series of five PMTs involving the head and neck and demonstrate the diagnostic utility of fluorescence in situ hybridization (FISH) for detecting FGFR1 translocations. Patients' age and sex, tumor location, original diagnosis, the duration of symptoms, the presence of TIO, biochemical results, and medical management were reviewed. The median age at presentation was 45 (range, 24-58 years) and TIO was present in three cases. Four tumors involved soft tissue and one involved bone. Four out of the five tumors in our series were initially misdiagnosed. Three tumors were ultimately categorized as malignant PMT (two patients developed metastatic disease). FGFR1 translocation was present in two out of four cases and remained unknown in one case. In summary, we report on five cases of PMTs arising in the head and neck and confirm utility of FGFR1 FISH in the diagnosis of a subset of PMT.

Sinonasal Phosphaturic Mesenchymal Tumor: A Rare and Misinterpreted Entity

Objectives Oncogenic osteomalacia is a paraneoplastic syndrome in which the tumor secretes a peptide-like hormone, fibroblast growth factor, resulting in urinary loss of phosphates. Methods We present the case of a 50-year-old woman with a benign phosphaturic mesenchymal tumor (PMT) involving the ethmoid sinus with obstruction of the ostiomeatal complex causing unilateral nasal airway obstruction. Results The tumor was initially thought to be an esthesioneuroblastoma based on primary pathology interpretation and on clinical and radiographic appearance. However, a benign PMT was later confirmed by further testing. Conclusion The tumor was removed entirely by the endoscopic transnasal approach, leading to a full resolution of symptoms.

A case of oncogenic osteomalacia due to occult nasal sinus tumor

This paper shows a case of oncogenic osteomalacia in a 35-year-old man who presented with a 2-year history of generalized pain and progressive weakness of lower limbs, eventually became bed bound. At admission he had severe hip pain resulting from atraumatic femoral neck fractures. Laboratory investigations revealed hypophosphatemia, hyperphosphaturia, normocalcemia, elevated alkaline phosphatase, and normal serum levels of parathormone and 25-hydroxyvitamin D. Serum FGF-23 was elevated. Imaging showed osteoporosis and insufficiency fractures of the femoral neck. Whole body functional imaging failed to reveal any areas of increased activity. However, on computed tomography (CT) and magnetic resonance (MR) imaging, a tumor was discovered at left nasal cavity. The patient was treated with phosphate supplements and vitamin D, but his hypophosphatemia persisted. The tumor was surgically removed. Histologically, the tumor was diagnosed as variant of a sinonasal hemangiopericytoma-like tumor. After surgery, his symptoms were relieved and biochemical parameters normalized.

Oncogenic osteomalacia caused by an occult paranasal sinus tumor

Oncogenic osteomalacia (OOM) is a rare bone disease characterized by inadequate bone mineralization and is caused by a humoral factor mainly produced by benign mesenchymal tumors. We report a case of OOM caused by an occult phosphaturic mesenchymal tumor in the paranasal sinus. The causative tumor was small and localized in the ethmoid sinus, and the patient did not exhibit any nasal symptoms. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) depicted the location of the occult tumor, and systemic venous sampling followed by assessments of the samples' fibroblast growth factor 23 (FGF23) concentrations confirmed that the tumor secreted FGF23. The tumor was resected via an external surgical approach, resulting in the complete relief of the patient's symptoms. The combination of FDG-PET and systemic venous sampling to assess serum FGF23 levels is useful for identifying small asymptomatic OOM-associated tumors. Such tumors are rare, but a significant proportion of them develop in the head and neck region, and complete resection is the most effective treatment. It is important that ENT surgeons are aware of the characteristics of OOM.

Sinonasal phosphaturic mesenchymal tumor: Case report and systematic review

We report a case of sinonasal phosphaturic mesenchymal tumor (PMT) and conduct a systematic review of the literature to highlight a unique paraneoplastic syndrome associated with PMT. We used English language publications from Medline and Cochrane databases (1970-2013) as data sources. A systematic review of the literature was conducted. All reported cases of head and neck PMTs were included. The presence or absence of the associated paraneoplastic syndrome was noted. We found 33 cases of PMT in the head and neck reported in the literature, 17 of which occurred in the sinonasal area. Approximately 5% of all PMTs are located in the head and neck. Just greater than half are concentrated in the sinonasal area, and the remaining involve various bony and soft tissue structures of the head and neck. PMT is sometimes associated with a paraneoplastic syndrome of tumor-induced (oncogenic) osteomalacia (TIO) causing bone pain, muscle weakness, and pathologic fractures. We present the 18th reported case of sinonasal PMT. A smooth mucosa-covered midline intraseptal mass filling the posterior nasal cavity with destruction and erosion of the skull base was found in an adult male. The patient underwent successful endoscopic resection with wide negative margins and is without recurrence at 24-month follow-up. PMT is a benign, locally aggressive tumor with rare malignant transformation. Knowledge of the bony invasion and destruction caused by this tumor is essential in planning surgical resection with wide negative margins. Familiarity with the associated TIO is essential to investigate for and manage any associated bony morbidity.

Sinonasal glomangiopericytoma causing oncogenic osteomalacia

A 60-year-old woman suffered from recurrent femur neck fracture. Laboratory data showed serum hypophosphatemia, elevated alkaline phosphatase, normal serum calcium levels, and normal parathyroid hormone levels. Radiological examinations revealed a tumor in the right maxillary alveolar bone. The nasal cavity mass was removed, and the histological features were those of glomangiopericytoma. After removal of the tumor, some of the laboratory data normalized. Based on the clinical features, histopathological diagnosis and postoperative course of events, a diagnosis of glomangiopericytoma causing oncogenic osteomalacia was confirmed. We report a case of oncogenic osteomalacia caused by sinonasal glomangiopericytoma.

Intracranial phosphaturic mesenchymal tumors

Hypophosphatemia with osteomalacia may be due to a neoplasm that produces fibroblast growth factor 23 (FGF-23), which inhibits phosphate reabsorption in the kidneys. Most of these tumors occur in bone or soft tissue and occasionally in the head, although intracranial occurrence is very rare. This report describes a tumor that caused hypophosphatemia and osteomalacia and was located entirely in the right anterior cranial fossa. Radiologically, the tumor resembled a meningioma; histologically, it was a low-grade phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). After gross-total resection, the patient's symptoms abated and laboratory values normalized. The authors also studied another PMTMCT initially diagnosed as a hemangiopericytoma that involved the left anterior cranial fossa and ethmoid sinus, and reviewed reports of 6 other intracranial tumors that induced osteomalacia, 3 entirely in the anterior cranial fossa, 2 involving the anterior cranial fossa and ethmoid sinus, and 1 in the cavernous sinus. In older children or adults who have hypophosphatemia with osteomalacia and no personal or family history of metabolic, renal, or malabsorptive disease, a neoplasm should be suspected and an imaging workup that includes the brain is warranted, with particular attention to the anterior cranial fossa. Additionally, because there are some overlapping histological features between PMTMCTs and hemangiopericytomas, it may be helpful to assess tumoral FGF-23 expression by reverse transcriptase polymerase chain reaction or immunohistochemical analysis in patients with oncogenic osteomalacia from an intracranial tumor diagnosed as, or resembling, hemangiopericytoma.

Oncogenic osteomalacia -- hypophosphataemic spectrum from "benignancy" to "malignancy"

Though case reports and case series about oncogenic osteomalacia due to benign mesenchymal tumours and much more rarely, secondary to malignant ones exist in the literature, there has not been any series reported from a single department spanning the gamut of causes from benign to malignant. We present 3 patients who were seen at the department of endocrinology of our hospital between 2010 and 2012 with hypophosphataemia and severe skeletal complications. All of them were found to have oncogenic osteomalacia otherwise known as tumour induced osteomalacia (TIO) - a paraneoplastic syndrome characterised by renal phosphate wasting and severe hypophosphataemia. The implicating tumours in our patients ranged from a subcutaneous mesenchymal tumour in the heel to a mixed connective tissue variant within the nasal cavity to metastatic prostate cancer. All our patients had protracted periods before the diagnosis was made, during which time the burden of their metabolic and skeletal pathology had increased. A timely recognition of the clinical features and biochemical findings of this rare but potentially debilitating disease is critical. Physicians should be cognizant of the presence of the disease and its localising and treatment strategies.

Oncogenic osteomalacia associated with mesenchymal tumor in the middle cranial fossa: a case report

INTRODUCTION

Tumor-induced osteomalacia is a paraneoplastic syndrome of hypophosphatemia. Osteomalacia causes multiple bone fractures and severe pain.

CASE PRESENTATION

We report the case of a 57-year-old Japanese man with tumor-induced osteomalacia associated with a middle cranial fossa bone tumor. The tumor was successfully resected by using a middle fossa epidural approach. His phosphate level recovered to a normal range immediately after the surgery.

CONCLUSIONS

It is rare that tumor-induced osteomalacia originates from the middle skull base. This report suggests that, if patients have a clinical and biochemical picture suggestive of tumor-induced osteomalacia, it is crucial to perform a meticulous examination to detect the tumor or the lesion responsible for the tumor. The serum level of fibroblast growth factor 23 is the most reliable marker for evaluating the treatment outcome of tumor-induced osteomalacia.

Striking pathology gold: a singular experience with daily reverberations: sinonasal hemangiopericytoma (glomangiopericytoma) and oncogenic osteomalacia

Sinonasal hemangiopericytoma-like tumors(SNHPC)(glomangiopericytomas)were originally conceived as histologically similar to, but biologically distinct from, their soft tissue counterparts. Re-evaluation of "hemangiopericytiomas" has determined that SNHPC (glomangiopericytomas) represent bona-fide pericyte-derived tumors, whereas most soft tissue neoplasms previously designated as hemangiopericytomas represent cellular variants of solitary fibrous tumors or other lesions with a hemangiopericytomalike growth pattern. We present an interesting case of a woman with SNHPC (glomangiopericytomas) causing oncogenic osteomalacia, and discuss the recent advances in our understanding of phosphaturic mesenchymal tumors. This particular case is an example of "Striking Pathology Gold"-a situation where the pathologist actively guides the diagnostic process, and witnesses its repercussions. "Striking Pathology Gold" may be a rare event in one's career. However it serves to remind us of our place in the world as physicians. Working behind the scenes, we quietly change the course of countless individual destinies for the better.

Nasal hemangiopericytoma causing oncogenic osteomalacia

Oncogenic osteomalacia is a rare cause that makes abnormalities of bone metabolism. Our case arose in a 47-year-old woman presenting a nasal mass associated with osteomalacia. We excised the mass carefully. After surgery, it was diagnosed as hemangiopericytoma and her symptoms related with osteomalacia were relieved and biochemical abnormalities were restored to normal range. We report and review a rare case of nasal hemangiopericytoma that caused osteomalacia.

Phosphaturic mesenchymal tumour of the sinonasal area: case report and review of the literature

Background

Oncogenous osteomalacia (OOM), which is also known as tumour-induced osteomalacia, is a rare condition associated with a neoplasm and a related systemic bone demineralization caused by renal phosphate wasting. OOM usually occurs in association with a variety of different mesenchymal tumours, and they were categorized into four distinct morphological patterns which they termed "phosphaturic mesenchymal tumour". Of its 4 histopathological subtypes, the mixed connective tissue variant is most commonly observed. Only 10% of cases appear in the head and neck regions and moreover, only 5 previously published tumors were localized in the sinonasal area. The authors describe a case of a man with a PMT originating from the frontoethmoidal region.

Case presentation

A 53-year-old man was referred to our ORL clinic due to a presence of a mass at the nasal root having been growing asymptomatically for 1 year. CT scans demonstrated a large (25 × 20 × 35 mm) bilateral frontoethmoidal mass with destruction of nasal bones. The tumor did not appear to invade to the anterior skull base. A selective angiography revealed a moderate hypervascularization of the tumour during early and late arterial phases. The tumour was removed from the external approach and the definitive histopathological diagnosis was a phospaturic mesenchymal tumor. Dual energy X-ray absorptiometry revealed a slight osteopenia of the first and second lumbar vertebrae and neck of the thigh bone. The serum and urinary levels of both calcium and anorganic phosphate were within normal limits. The patient is doing well three years after the operation, and the serum and urine levels of calcium and phosphate remain well within normal limits.

Conclusion

PMT is rare in the sinonasal region, it can be rarely observed without the signs of osteomalacia.

Malignant mesenchymoma in the nasal cavity of a bull

A 4-year-old bull was presented with facial distortion and abnormal respiratory noise. Endoscopically, a proliferative mass was found obliterating the left nasal cavity and a tumour was suspected. The head was examined after slaughter and there was a well-circumscribed solid structure (15×12×6 cm) extending into the paranasal sinus, the choanal region and the bones of the orbit, with focal penetration of the nasal septum. Microscopically, the mass consisted of well-differentiated trabeculae of woven and lamellar bone, areas of chondromyxomatous, immature and mature cartilaginous tissue, and regions with irregular whorled spindle cells. Tissue differentiation of the mass was variable. Centrally, there was osseous differentiation with an outermost fibromatous area resembling a zone of endochondral ossification. There was suppurative and ulcerative inflammation where the tumour extended through the hard palate and into the pharynx. A nasal malignant mesenchymoma was diagnosed on the basis of these features.

Oncogenic osteomalacia from nasal cavity giant cell tumor

BACKGROUND

Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by osteomalacia, which occurs as a result of excess renal phosphate excretion caused by fibroblast growth factor-23 secreted by mesenchymal tumors. This entity is rare in head and neck cancers. We report a rare case of oncogenic osteomalacia in a patient with an anterior skull base giant cell tumor.

METHODS AND RESULTS

A 34-year-old woman presented with a 5-year history of progressive weakness in both lower limbs and the trunk. Hypophosphatemia and hypocalcemia had been noted by a local physician, but her symptoms persisted despite receiving calcium and vitamin D supplements. A recent onset of epistaxis and nasal blockage led to referral to the head and neck services. Nasal endoscopy revealed a left nasal cavity mass. Further evaluation with imaging studies revealed a mass in the nasal cavity with intracranial extension. Biopsy of the lesion suggested a neurogenic tumor. A putative diagnosis of anterior skull base neurogenic tumor with paraneoplastic hypophosphatemia was made. After the biochemical parameters were corrected, the patient underwent craniofacial resection. The final histopathologic study suggested the lesion as a "giant cell tumor." During the postoperative period the patient's biochemical and clinical symptoms improved dramatically, allowing her to regain normal mobility.

CONCLUSIONS

Clinicians and pathologists must be aware of the clinical symptoms, laboratory abnormalities, and pathologic features of oncogenic osteomalacia, which may be caused by tumors in the head and neck and thus make an exhaustive effort to diagnose the same.

Mesenchymal phosphaturic neoplasm in the maxillary sinus: a case report

The authors describe a case of oncogenic osteomalacia due to a mesenchymal phosphaturic tumour in the maxillary sinus. This is a paraneoplastic syndrome in which a tumour produces a peptide hormone-like substance (phosphatonin) that causes a urinary loss of phosphates resulting in a debilitating systemic condition. In this case, the patient experienced muscle stiffness, reduction of muscle tone, loss of weight and pathological fractures. Clinical and radiological examination revealed a tumour in the right maxillary sinus; all other results were negative. The diagnosis following pathology examination was mesenchymal phosphaturic tumour with a haemangiopericytoma-like vascular pattern. Different histological types of mesenchymal tumours can be associated with paraneoplastic syndrome, but their localization in the paranasal sinuses is rare. The correct diagnosis allows the appropriate therapeutic approach, which can lead to an almost immediate resolution of the clinical situation after surgical removal of the neoplasm as in the present case. Oncogenic osteomalacia is rare, particularly in the maxillofacial region, and only a few cases have been reported.

[Oncogenic osteomalacia due to phosphaturic mesenchymal tumour in infratemporal fossa]

Oncogenic osteomalacia is an uncommon syndrome characterized by phosphaturic tumours that produce mineral metabolism abnormalities. Head and neck is the second most frequent location of these tumours. We describe a case of a phosphaturic mesenchymal tumour in the infratemporal fossa that caused oncogenic osteomalacia, resolved by means of surgical excision.

Tumor-induced osteomalacia originating from the temporal bone: a case report

BACKGROUND

Tumor-induced osteomalacia (TIO) is a rare clinical entity in which secondary osteomalacia is induced by tumor-related products. Fibroblast growth factor 23 (FGF-23) mRNA is overexpressed in the tumor tissue, leading to impaired reabsorption of phosphorus in the renal tubules and hypophosphatemia. Curative treatment is considered to be total resection of the tumor.

METHODS AND RESULTS

A 53-year-old woman had experienced systemic bone pain and muscle weakness for several years. She had refractory hypophosphatemia and marked elevation of serum FGF-23 level. Whole body imaging eventually revealed a hypervascular mass in the right temporal bone, leading to a diagnosis of TIO. She underwent skull-base surgery after embolization of the tumor. After the en bloc resection, FGF-23 became undetectable, phosphate reabsorption normalized, and all symptoms resolved.

CONCLUSIONS

We discuss the clinical features and treatment options for this rare disease.

A 9-month-old phosphaturic mesenchymal tumor mimicking the intractable rickets

Phosphaturic mesenchymal tumor is an extremely rare disease and is frequently associated with oncogenic osteomalacia showing paraneoplastic syndrome, which is characterized by phosphaturia, hypophosphatemia, normocalcemia, and decreased levels of 1,25-dihydroxyvitamin D3 associated with a tumor. A 2-year-old boy, who had a soft tissue tumor on his right thigh and previously diagnosed as myositis ossificans at 9-months-old, was presented with rachitic rosary and mildly enlarged tumor. Biochemical investigations showed hypophosphatemia, hyperphosphaturia, and an increased alkaline phosphatase level of 440 U/l (25-100 U/l), suggesting rickets, which was resistant to vitamin D dietary supplementation. We were certain of intractable rickets because of oncogenic hypophosphatemia and thus decided to excise the soft tissue mass. We observed laboratory improvement of rickets after 2 weeks. On the basis of surgical and histopathological examinations, the tumor was finally diagnosed as the phosphaturic mesenchymal tumor.

Oncogenic osteomalacia in a patient with an ethmoid sinus tumour

OBJECTIVE

To highlight the clinical presentation and management of a rare case of oncogenic osteomalacia due to an ethmoid sinus tumour.

MATERIALS AND METHODS

We examined the case records of a 55-year-old man who presented with progressive fatigue, weakness and bone pain, and noted the clinical presentation, laboratory investigations, computed tomography findings, operative notes and follow-up details.

CONCLUSION

Oncogenic osteomalacia secondary to a paranasal sinus neoplasm is a rare entity. The causative tumour is often occult and may be missed by routine clinical examination. This case report illustrates the appropriate pattern of evaluation and management to ensure a successful outcome.

Oncogenic osteomalacia from pterygopalatine fossa mass

INTRODUCTION

Oncogenic osteomalacia, or tumour-induced osteomalacia, is an uncommon cause of osteomalacia. It has been reported to occur in patients with hypophosphataemia due to excess renal phosphate excretion secondary to mesenchymal tumours. Occurrence of this pathological process in the head and neck is extremely rare.

METHODS

Case report and literature review.

RESULTS

We present a case of a 73-year-old woman with tumour-induced osteomalacia. She was initially followed by the endocrinologists for osteomalacia and pathological fractures. An indium-111 pentetreotide scan showed activity in the left pterygopalatine fossa. A mass was endoscopically resected, and the histopathological appearance was consistent with a haemangiopericytoma. Following surgery, the patient's hypophosphataemia and vitamin D deficiency corrected and her symptoms resolved.

CONCLUSIONS

Oncogenic osteomalacia, or tumour-induced osteomalacia, is a rare entity in the head and neck. Current research is elucidating the mechanism by which phosphaturic wasting occurs. In most patients, symptoms resolve once the offending tumour is removed.

Phosphaturic mesenchymal tumor diagnosed by fine-needle aspiration and core biopsy: a case report and review of literature

Oncogenic (tumor-induced) osteomalacia is a rare paraneoplastic syndrome of phosphate wasting that is frequently associated with phosphaturic mesenchymal tumor (PMT). As the cytologic features of this tumor apparently have not been reported, we describe the fine-needle aspiration (FNA) findings for PMT that arose from the gluteal soft tissue in a patient with hypophosphatemia and multiple fractures secondary to osteomalacia. Smears from the computerized tomography (CT)-guided FNA showed groups of spindle cells having elongated nuclei, fine to moderately coarsely granular chromatin, inconspicuous nucleoli, and delicate cytoplasm. Marked nuclear atypia, mitotic figures, and necrosis were absent. The differential diagnosis included a variety of benign and malignant spindle cell neoplasms such as monophasic synovial sarcoma, leiomyoma, peripheral nerve sheath tumor, fibrosarcoma, and, less likely, metastatic melanoma and sarcomatoid carcinoma. The bland-appearing cytologic features of a spindle cell tumor in a patient with osteomalacia should suggest the diagnosis of PMT.

Imaging in the investigation of paraneoplastic syndromes

Paraneoplastic syndromes are a heterogeneous group of disease presentations caused by underlying tumours. As they are non-metastatic in nature an intensive diagnostic evaluation is warranted to identify potentially curable lesions. The selection of the appropriate method of imaging is important in these cases, especially when history and physical examination are unrevealing. In this review the important paraneoplastic syndromes and underlying malignancies are discussed along with relevant imaging strategies.

Oncogenic hypophosphatemic osteomalacia associated with a nasal hemangiopericytoma

We report a patient with a nasal hemangiopericytoma associated with an oncogenic hypophosphatemic osteomalacia (OHO). This syndrome results from tumor products that decrease renal tubular phosphate resorption, leading to the osteomalacia. This patient presented with classic bone manifestations of osteomalacia and a nasal tumor. Laboratory studies performed before the first resection of the tumor included normal serum calcium, hypophosphatemia due to decreased tubular reabsorption of phosphate, and an undetectable serum 1,25 dihydroxy vitamin D level. Serum parathormone level was normal. Anterior iliac crest bone biopsy showed characteristic signs of osteomalacia that included increased osteoid and delayed mineralization. A partial resection of the nasal tumor was performed. After the first surgery the patient showed detectable serum level of 1,25 dihydroxy vitamin D, and transient normalization of the tubular reabsorption of phosphate. The patient was also treated with phosphate supplements and vitamin D with transient control of her clinical manifestations and improvement of the radiographic signs of osteomalacia. Three months after surgery, the serum level of 1,25 dihydroxy vitamin D level again became undetectable. After selective embolization of the tumor, followed by an apparent complete tumor resection and postoperative radiation therapy, her hypophosphatemia and decreased phosphate tubular reabsorption persisted. Therefore, biochemical changes associated with hemangiopericytoma induced OHO may persist even after apparent total tumor resection. Clinicians should be aware of the oncogenic basis for some osteomalacia, as seen in this patient.

A haemangiopericytoma of the ethmoid sinus causing oncogenic osteomalacia: a case report and review of the literature

Oncogenic osteomalacia is a rare cause of osteomalacia. It is caused by a tumour which is generally benign. These tumours, when identified, are often found in the head and neck region. The case is reported here of a haemangiopericytoma isolated in the ethmoid sinus, and the literature regarding tumours at this site is reviewed. Including the present case there are five reported in the world literature of an ethmoid sinus tumour causing oncogenic osteomalacia. The treatment for this disease is excision of the mass, which is where the head and neck specialist's expertise is required.

Oncogenic osteomalacia: exact tumor localization by co-registration of positron emission and computed tomography

In oncogenic osteomalacia, the causative tumor is almost always difficult to find. A novel diagnostic approach is presented that facilitates a precise and rapid localization of the associated lesion by PET-CT co-registration using the radiotracer (68)Ga-DOTANOC.

INTRODUCTION

Oncogenic osteomalacia (OOM) is an uncommon disorder characterized by hyperphosphaturia, hypophosphatemia, decreased vitamin D(3) serum levels, and osteomalacia. The paraneoplastic syndrome is exclusively driven by a small somatostatin receptor (sst)-positive tumor that produces phosphatonins, proteins that cause renal phosphate loss. OOM can be cured completely on tumor removal. However, the exact tumor localization is the most challenging step, because the lesion is notoriously difficult to detect by common imaging techniques.

MATERIALS AND METHODS

A 60-year-old woman complained of severe pain in her back and chest wall, muscle weakness, and reduced physical activity for >1 year. She suffered a metatarsal fracture and presented with hyperphosphaturia and hypophosphatemia. OOM was suspected, and a meticulous search for the tumor was initiated by conventional imaging techniques, sst-mediated imaging using (111)In-octreotide scintigraphy, and (68)Ga-DOTANOC-based positron emission tomography (PET)-CT co-registration. (68)Ga-DOTANOC is a novel radiopharmaceutical compound in which the somatostatin analog octreotide is modified at position 3, chelated with DOTA, and complexed with (68)Gallium. (68)Ga-DOTANOC has an improved affinity to sst2 and sst5 relative to other radiopeptides.

RESULTS

Whereas common imaging techniques such as CT failed to localize the tumor, (111)In-octreotide scintigraphy was able to detect the lesion, but only PET-CT using (68)Ga-DOTANOC revealed the exact tumor localization in the right femoral head. On tumor resection, the well being of the patient improved significantly, and biochemical parameters returned to normal.

CONCLUSIONS

(68)Ga-DOTANOC-based PET-CT is a novel and powerful approach to detect sst-positive tumors in a timely manner and to provide highly resolved images facilitating the development of a therapeutic strategy.

Oncogenic osteomalacia in a case with a maxillary sinus mesenchymal tumor

We herein describe the rare case of a 41-year-old woman with oncogenic osteomalacia due to a tumor in the maxillary sinus who presented with chronic general pain that had been gradually deteriorating. The patient's laboratory findings revealed hypophosphatemia due to renal phosphate wasting, an inappropriately low serum 1 alpha,25-dihydroxyvitamin D3 level for hypophosphatemia and an unusually high serum level of fibroblast growth factor 23 (FGF23). The causative tumor was surgically removed, resulting in a rapid resolution of the patient's biochemical abnormalities. An improvement of the abnormal multiple deposits on (99)Technetium-methylene diphosphonate bone scintigraphy and an increase in the bone metabolism markers suggested the development of bone remodeling within 49 days after the operation. The pathologic diagnosis of the tumor was a "phosphaturic mesenchymal tumor, mixed with a connective tissue variant." The expression of FGF23 was demonstrated in the tumor by the immunohistochemical techniques and a Western analysis.

Secondary hyperparathyroidism as a palpable intrathyroid parathyroid gland in a patient with hypophosphatemic osteomalacia

Secondary hyperparathyroidism is sometimes seen in patients with hypophosphatemic osteomalacia after long-term oral phosphate therapy. Parathyroidectomy is sometimes needed for the correction of hypercalcemia in these patients, and is rarely performed in patients without hypercalcemia. A 46-year-old female patient had hypophosphatemic osteomalacia with unknown cause and secondary hyperparathyroidism. A palpable neck mass developed after long-term oral phosphate therapy. An intrathyroid parathyroid gland was confirmed through partial thyroidectomy and parathyroidectomy. Renal phosphate wasting decreased strongly, and serum parathyroid hormone was in the normal range after the operation. A correction of secondary hyperparathyroidism may partially overcome hyperphosphaturia in some patients with hypophosphatemic rickets.

Hypophosphaturic mesenchymal tumor of the ethmoid associated with oncogenic osteomalacia

Oncogenic osteomalacia is an uncommon syndrome characterized by bone pain, proximal muscle weakness, hypophosphatemia, hyperphosphaturia, and a low plasma concentration of 1,25-dihydroxy-vitamin D. The disease affects both sexes at around 40 years of age, although it can sometimes affect children and adolescents. Generally, the syndrome is associated with a tumor, usually benign, of mesenchymal origin and is resolved after removal of the tumor; this syndrome can sometimes be associated with malignant tumors. These tumors seem to be histologically heterogeneous and are generally localized in soft tissues and bone. In this article, a case of oncogenic osteomalacia associated with a hypophosphaturic mesenchymal tumor of the ethmoid is reported in a 24-year-old man. After surgical and radical removal of the tumor, the patient noted a decrease in the clinical symptoms and signs.

Most osteomalacia-associated mesenchymal tumors are a single histopathologic entity: an analysis of 32 cases and a comprehensive review of the literature

Oncogenic osteomalacia (OO) is a rare paraneoplastic syndrome of osteomalacia due to phosphate wasting. The phosphaturic mesenchymal tumor (mixed connective tissue variant) (PMTMCT) is an extremely rare, distinctive tumor that is frequently associated with OO. Despite its association with OO, many PMTMCTs go unrecognized because they are erroneously diagnosed as other mesenchymal tumors. Expression of fibroblast growth factor-23 (FGF-23), a recently described protein putatively implicated in renal tubular phosphate loss, has been shown in a small number of mesenchymal tumors with known OO. The clinicopathological features of 32 mesenchymal tumors either with known OO (29) or with features suggestive of PMTMCT (3) were studied. Immunohistochemistry for cytokeratin, S-100, actin, desmin, CD34, and FGF-23 was performed. The patients (13 male, 19 female) ranged from 9 to 80 years in age (median 53 years). A long history of OO was common. The cases had been originally diagnosed as PMTMCT (15), hemangiopericytoma (HPC) (3), osteosarcoma (3), giant cell tumor (2), and other (9). The tumors occurred in a variety of soft tissue (21) and bone sites (11) and ranged from 1.7 to 14 cm. Twenty-four cases were classic PMTMCT with low cellularity, myxoid change, bland spindled cells, distinctive "grungy" calcified matrix, fat, HPC-like vessels, microcysts, hemorrhage, osteoclasts, and an incomplete rim of membranous ossification. Four of these benign-appearing PMTMCTs contained osteoid-like matrix. Three other PMTMCTs were hypercellular and cytologically atypical and were considered malignant. The 3 cases without known OO were histologically identical to the typical PMTMCT. Four cases did not resemble PMTMCT: 2 sinonasal HPC, 1 conventional HPC, and 1 sclerosing osteosarcoma. Three cases expressed actin; all other markers were negative. Expression of FGF-23 was seen in 17 of 21 cases by immunohistochemistry and in 2 of 2 cases by RT-PCR. Follow-up (25 cases, 6-348 months) indicated the following: 21 alive with no evidence of disease and with normal serum chemistry, 4 alive with disease (1 malignant PMTMCT with lung metastases). We conclude that most cases of mesenchymal tumor-associated OO, both in the present series and in the reported literature, are due to PMTMCT. Improved recognition of their histologic spectrum, including the presence of bone or osteoid-like matrix in otherwise typical cases and the existence of malignant forms, should allow distinction from other mesenchymal tumors. Recognition of PMTMCT is critical, as complete resection cures intractable OO. Immunohistochemistry and RT-PCR for FGF-23 confirm the role of this protein in PMTMCT-associated OO.

Oncogenic osteomalacia associated with mesenchymal tumour detected by indium-111 octreotide scintigraphy

In a 40-year-old man who had suffered from vague and generalized bone pains for 7 years due to oncogenic osteomalacia, the causative tumour was finally detected by Indium-111 octreotide scintigraphy. Some characteristics of the tumour associated with oncogenic osteomalacia, such as its size, growth rate, location and origin, often make the diagnosis difficult. However, the recent discovery of somatostatin receptors in mesenchymal tumours, which are the most common cause of oncogenic osteomalacia, has raised the possibility of early detection of this devastating disorder. Here, we report that radiolabelled octreotide scintigraphy has a potential role as a diagnostic tool in oncogenic osteomalacia. However, the exact role of somatostatin receptors in tumours associated with oncogenic osteomalacia still remains elusive.