Tumor-Induced Osteomalacia: an Up-to-Date Review

Challenges in the diagnosis and management of tumor-induced osteomalacia: A case report

The present case report is aimed to highlight the difficulty and the reason for the delayed diagnosis of phosphaturic mesenchymal tumors, emphasizing the need of standardized protocols for diagnosis, surgery and follow-up in high-volume hospitals. The clinical signs and symptoms, diagnostic and therapeutic procedures, immunohistological features were analyzed. Delayed diagnosis of phosphaturic mesenchymal tumor was primarily due to non-specific clinical symptoms such as fatigue, muscular and bone pain, and multiple fractures. This cryptic clinical picture made the diagnosis tricky that led to treatment of patient for non-specific pain and stress fractures before to consider the tumor-induced osteomalacia syndrome. Some well-documented studies were found in the literature in which the history of trauma is a critical trigger of glomus tumors. Extra-subungual tumors most frequently occur in the knee and ankle regions, particularly among young adults, and the diagnosis is typically made approximately 7.2 years after initial symptom onset. The difficult tumor localization represented an additional obstacle to the prompt treatment, leading to delayed curative surgery.

Phosphaturic mesenchymal tumor: Clinicopathological features with outcomes in 10 patients with review of literature

BACKGROUND

Phosphaturic mesenchymal tumors (PMTs) are rare mesenchymal tumors, associated with long-standing, non-specific but often debilitating symptoms in the affected patients. These tumors display characteristic histopathological features and in case, identified timely, can be a boon for patients, given an excision is completely curative.

AIMS

To evaluate the clinical and histopathological features of 10 PMTs, diagnosed at our institution, along with clinical outcomes in those patients.

MATERIALS AND METHODS

This was a retrospective study, wherein 10 PMTs, diagnosed from January 2013 to July 2022, were included.

RESULTS

The average age at the time of diagnosis was 40 years with an M:F ratio of 4:1. Clinical features included lumps, weakness, bone pain, difficulty in moving and walking, and pathologic fractures. The biochemical analysis showed normal serum calcium levels (average = 9.5 mg/dL), with low serum phosphorus (average = 2.2 mg/dL) and raised serum fibroblast growth factor 23 (FGF23) levels, in all the cases, wherever available. On histopathology, all tumors showed cells arranged in a hemangiopericytomatous pattern, including oval to short spindle forms. Multinucleate giant cells were present in nine tumors, and characteristic "grungy calcifications" was observed in eight tumors. Prominent pseudo cystic spaces were seen in eight tumors. A significant number of mitotic figures and tumor necrosis were not seen in any tumor. In five cases where follow-up was available, there was complete resolution of symptoms post-resection with no recurrence or metastasis. All those patients were free of disease until the last follow-up.

CONCLUSION

This constitutes the first largest comprehensive study on these rare tumors from our country. PMTs can be diagnosed based on certain histopathological features and correlation with clinicoradiological and biochemical findings. These are invariably benign neoplasms. Patients are relieved of their debilitating symptoms after adequate surgical tumor resection. Therefore, their correct and timely diagnosis is crucial.

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.

Epidemiology of Tumor-Induced Osteomalacia in Germany Based on Real World Data

Tumor-induced osteomalacia (TIO) is an ultra-rare disease caused mostly by benign tumors that secrete fibroblast growth factor-23. Because of nonspecific symptoms, the diagnostic delay is long, and therapy can be challenging. Moreover, epidemiological data on TIO are scarce owing to its rarity. Therefore, this study aimed to quantify TIO's incidence rates and prevalence in Germany. Retrospective longitudinal and cross-sectional analyses were conducted using anonymized German claims data from the statutory health insurance (SHI) database. This database, which comprises the data of approximately 5 million insurants, is a representative sample of the German population and supports national projections. As there is no unique International Statistical Classification of Diseases and Related Health Problems (ICD) code for TIO, operational categories based on different surrogates were defined to determine the prevalence and incidence rates of TIO among probable patients. This study showed that TIO has a prevalence of (documented code, advanced imaging, medication, or tumor removal) 0.187 per 100,000 persons and an incidence rate of ≤ 0.094 per 100,000 person years. This analysis provides the first epidemiological insight into German patients with TIO. Despite the general limitations associated with the analysis of SHI claims data of ultra-rare diseases, we believe that this analysis provides a sound basis for further analysis, particularly with regard to the care situation of patients with TIO.

Phosphaturic Mesenchymal Tumor Along the Hallux side Inducing a Chronic non-Healing Wound: A Case Report with Literature Review

Phosphaturic mesenchymal tumor (PMT) is a rare paraneoplastic syndrome characterized by renal phosphate wasting, hypophosphatemia, and bone calcification disorders. Complete surgical resection of the tumor is believed to be the most effective treatment measure. However, the diagnosis of PMT is very difficult because of its insidious and small size, especially, when it appears in subcutaneous tissue with a chronic non-healing wound. We report a rare case of a 38-year-old man with a chronic non-healing wound on the left hallux for approximately eight months. Plain radiographic images and magnetic resonance imaging (MRI) revealed a cystic radiolucent shadow in the left distal phalanx. Bone scan observations also showed increased uptake in the same location. Histologically, this tumor was composed of numerous spindle cells with clusters of giant cells. The serum FGF23 level was significantly higher before surgery, with higher FGF23 levels closer to the tumor. Reverse transcription polymerase chain reaction and immunohistochemistry further confirmed the high expression of FGF23 in tumors. These data suggest that FGF23 may be a potential causative factor of PMT. The serum FGF23 levels might be useful for the diagnosis of PMT and localization of the tumor. The tumor was CD56- and D2 to 40-positive and CD31-negative. The non-healing wound caused by PMT might be attributed to the invasive growth of the tumor, destruction of intercellular junctions, and decrease in the number of endothelial cells.

Sinonasal phosphaturic mesenchymal tumour: radiation oncologist's perspective

Tumour-induced osteomalacia is a rare cause of osteomalacia, the majority of which is of mesenchymal origin. Oncogenic osteomalacia is a potentially curable condition caused by phosphaturic mesenchymal tumours. We present the case of a woman in her 30s with a sinonasal phosphaturic mesenchymal tumour, treated with surgical excision followed by adjuvant intensity-modulated radiotherapy and subsequent adjuvant chemotherapy. The patient experienced minimal adverse effects during radiation. There was good local control and cosmetic outcomes with no radiation-related toxicity at a follow-up period of 32 months.

Unusual phosphaturic mesenchymal tumor mimicking osteoid osteoma

Phosphaturic mesenchymal tumor is a rare tumor characterized by paraneoplastic osteomalacia. The diagnosis is often delayed because of nonspecific symptoms and difficulty to localize the tumor. In this study we report a case of PMT of the left femur detected by Ga-68-DOTATATE PET-CT with radiological features mimicking osteoid osteoma. We report a 31-year-old female patient who presented to our hospital for evaluation due to progressive bone pain and muscle weakness. Her laboratory data showed hypophosphatemia and increased fibroblast growth factor 23 (FGF-23) together with reduced bone mineral density on bone densitometry. The diagnosis of PMT was suspected and the tumor was identified on Ga-68-DOTATATE PET-CT as a focal uptake in a lucent lesion of the left femoral head with a central sclerotic dot mimicking a nidus as seen in osteoid osteoma. The lesion was treated with percutaneous radiofrequency ablation. Laboratory tests and bone densitometry rapidly improved post-treatment. The present case emphasizes the difficulty to diagnose PMT due to its nonspecific biochemical and clinical presentation and the relevance of functional imaging for locating these tumors despite different radiological presentation.

Tumor induced osteomalacia from a peripheral mesenchymal tumour of the foot

Tumour induced osteomalacia (TIO) is a rare condition caused by peripheral mesenchymal tumours (PMT) which produce fibroblast-growth factor 23 (FGF23). FGF23 inhibits renal phosphate reabsorption leading to vitamin D resistant osteomalacia. The rarity of the condition and difficulty with isolating the PMT make diagnosis difficult, with delayed treatment leading to significant patient morbidity. We present a case of PMT of the foot with TIO, with a discussion on diagnosis and treatment.

Phosphaturic mesenchymal tumor in right thigh: 2 cases report and literature review

Background

Phosphaturic mesenchymal tumor (PMT) is a very rare tumor of bone and soft tissue that has no specific clinical manifestations. Here we present 2 cases of PMT in the right thigh, including comparatively adequate immunohistochemistry.

Case Presentation

We described 2 cases of PMT in the right thigh with manifestations of hypophosphatemia. PET-CT examination showed that both patients had lesions with increased expression of somatostatin receptors in the right thigh. Bland cells and dirty calcified stroma were exhibited under the microscope. And immunohistochemical detection of FGF-23 was positive.

Conclusions

PMT is a very uncommon tumor for which diagnosis and treatment are often delayed. Considering the importance of surgery for the treatment of this disease, a full understanding of its clinicopathological features will facilitate the diagnosis of this disease.

The Nose that Broke the Hip! Tumor Induced Osteomalacia Secondary to Phosphaturic Mesenchymal Nasal Tumor : A Case Report

Tumor induced osteomalacia is a rare paraneoplastic syndrome caused by usually small mesenchymal tumors. The tumors are commonly located in the extremities whereas occurrence in the nasal cavity is quite rare. An 18 year old male presented with asymmetric weakness of both lower limbs and difficulty in walking since one year. On evaluation he was found to have open femur head physes and iliac apophyses, low serum Phosphorus, low vitamin D, normal serum calcium, elevated PTH & alkaline phosphatase levels. FGF-23 levels in serum were elevated. DOTA NOC PET CT revealed tumor in the left nasal cavity abutting the nasal septum. Surgical excision of the tumor resulted in normalisation of the serum levels of phosphorus, vitamin D and FGF-23. This case report indicates the importance of maintaining high clinical suspicion and early detection of causative tumor using appropriate imaging techniques.

A literature review to understand the burden of disease in people living with tumour-induced osteomalacia

This study reviews publications to describe the signs, symptoms and impact of tumour-induced osteomalacia (TIO) on patients' burden of disease. TIO is associated with a spectrum of signs and symptoms imposing a significant clinical burden, but the psychosocial impact of this rare disease has been poorly researched so far.

INTRODUCTION

To describe the signs, symptoms and impacts of tumour-induced osteomalacia (TIO) and summarise the state of research on the burden of disease of this ultra-rare condition.

METHODS

A targeted literature review was conducted in PubMed using pre-defined search terms. Relevant articles published between 1980 and 2021 were screened for inclusion. Seventy records were selected for analysis. Data were extracted and grouped into categories and sub-categories to identify recurrent signs, symptoms and impacts of TIO and describe the burden on patients. Chord diagrams were created to analyse the relationships between different TIO outcomes and characterise the presentation of TIO.

RESULTS

Although the number of articles on TIO published have been increasing over the past 20 years, most studies were case reports and case series (n = 65/70) and only few were studies with higher quality of evidence (n = 5/70). Most articles were based on data reported by clinicians (n = 67/70). Patients with TIO experienced a combination of outcomes including chronic pain, weakness, skeletal-related manifestations and limitations in mobility. Only a few studies (n = 2/70) analysed the burden of TIO on the emotional wellbeing and on the work life of the patient.

CONCLUSION

Patients with TIO present with a spectrum of signs and symptoms that impose a significant burden. The impact on the psychosocial wellbeing of patients should be further investigated, as this has been poorly researched so far. Studies with high quality of evidence should be designed to further the understanding of the burden of disease of TIO from the patient's perspective.

Phosphaturic Mesenchymal Tumor: An Unusual Cause of Stress Fractures Presenting to Sports Medicine

Phosphaturic mesenchymal tumors (PMT) are a rare neoplasm oftentimes associated with tumor-induced osteomalacia (TIO). The non-specific presentation and symptoms of these pathologies make them difficult to diagnose. We report a case of a 52-year-old patient with an intermetatarsal phosphaturic mesenchymal tumor who presented to the orthopedic sports medicine clinic with metabolic deficiencies and bilateral subtrochanteric cortical stress fractures indicative of osteomalacia. The tumor was entirely resected within nine months of symptom onset and has shown no recurrence at the one-year follow-up. This case report characterizes an unusual cause of stress fractures presenting to orthopedic sports medicine clinics and the variability in the presentation of phosphaturic mesenchymal tumors.

Tumor-induced osteomalacia characterized by "painful knee joint with difficulty in moving": a case report

BACKGROUND

Tumor-related osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by severe hypophosphatemia and osteomalacia. The diagnosis of TIO can be very difficult because of its nonspecific nature of clinical manifestations. Here we reported a case of young TIO patient with "painful knee joint with difficulty in moving" to improve the clinical diagnosis and treatment levels.

CASE PRESENTATION

The patient's clinical features were consistent with TIO. A tumor was successfully located in left tibial by ⁶⁸Ga-DOTATATE PET/CT, and then was surgically resected. Upon pathologic assessment, the tumor was diagnosed as phosphaturia stromal tumor (PMT) with positive Vim staining. After the surgery, serum phosphate level rapidly recovered and symptoms significantly improved.

CONCLUSION

TIO should be considered in patients with chronically hypophosphorus osteomalacia in the setting of no family history. Early removal of the responsible tumors is clinically essential for the treatment, and imaging examination is of great significance for tumor localization.

Persistence and recurrence in tumor-induced osteomalacia: A systematic review of the literature and results from a national survey/case series

PURPOSE

Tumor induced osteomalacia (TIO) is a rare disease of mineral metabolism, whose clinical picture is dominated by hypophosphatemia usually due to an excess of circulating FGF23 produced by small mesenchymal tumors. Data on the real prevalence of the disease are lacking, with the knowledge of the disease mainly relying on case reports and small case series. No estimate is available on the prevalence of uncured TIO.

METHODS

National multi-center, cross-sectional and retrospective study on persistent or recurrent cases of TIO followed in referral centers for bone diseases; systematic review of the published persistent and recurrent cases of TIO. Data from patients consecutively evaluated in referral Italian centers for bone diseases were collected; a PubMed search on persistent, recurrent and unoperable cases of TIO was carried out.

RESULTS

Sixteen patients (mean age at diagnosis 52.5 ± 10.6 years) with persistent (n = 6, 37,5%), recurrent (n = 7, 43.7%) or not operable (n = 3, 18.8%) TIO were described. Delay in diagnosis (2.5 ± 1.3 years) was demonstrated. All patients experienced fragility fractures or pseudofractures and disabling bone and muscle pain. BMD was significantly reduced (mean T-score -2.7 ± 1.7 and -2.7 ± 0.9 at lumbar spine and femoral neck, respectively). Fourteen patients were maintained under therapy with phosphate salts and calcitriol, while in 2 patients therapy with burosumab, an anti-FGF23 antibody, was commenced.

CONCLUSION

A significant number of patients with TIO remain either undiagnosed for tumor localization or tumor recur or persist after surgery. These patients with active disease represent possible candidates for burosumab treatment.

PARANEOPLASTIC SYNDROMES REVIEW: THE GREAT FORGOTTEN ONES

Paraneoplastic syndromes (PNS) are a group of disorders that can affect the oncologic patient, and which are not directly attributable to tumour invasion, tumour compression or metastasis. In fact, they are due to tumour secretion of functional hormones or peptides or are related to immune cross-reactivity with the host tissue. These syndromes are called paraneoplastic because the components that cause them do not derive from the organ or tissue of origin, but from the neoplasm suffered by the patient. It is estimated that 10-15% of people with cancer suffer from a PNS.(1) PNS is the second direct cause of death (27% of cases) in cancer patients, after cancer itself. Consequently, it is of remarkable importance to recognize and treat SPNs specifically.(2) In view of the above, the aim of this article is to review the state of the art in neurological, haematological, endocrine, and dermatological paraneoplastic syndromes. It is a review in which the most relevant PNS and their symptomatology are described, inquiring into their diagnosis and treatment.

Challenges in the management of tumor-induced osteomalacia (TIO)

Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare acquired paraneoplastic disease, which is challenging to diagnose and treat. TIO is characterized by hypophosphatemia resulting from excess levels of tumor-secreted fibroblast growth factor 23 (FGF23), one of the key physiological regulators of phosphate metabolism. Elevated FGF23 results in renal phosphate wasting and compromised vitamin D activation, ultimately resulting in osteomalacia. Patients typically present with progressive and non-specific symptoms, including bone pain, multiple pathological fractures, and progressive muscle weakness. Diagnosis is often delayed or missed due to the non-specific nature of complaints and lack of disease awareness. Additionally, the disease-causing tumour is often difficult to detect and localize because they are often small, lack localizing symptoms and signs, and dwell in widely variable anatomical locations. Measuring serum/urine phosphate should be an inherent diagnostic component when assessing otherwise unexplained osteomalacia, fractures and weakness. In cases of hypophosphatemia with inappropriate (sustained) phosphaturia and inappropriately normal or frankly low 1,25-dihydroxy vitamin D, differentiation of the potential causes of renal phosphate wasting should include measurement of FGF23, and TIO should be considered. While patients experience severe disability without treatment, complete excision of the tumour is typically curative and results in a dramatic reversal of symptoms. Two additional key current unmet needs in optimizing TIO management are: (1 and 2) the considerable delay in diagnosis and consequent delay between the onset of symptoms and surgical resection; and (2) alternative management. These may be addressed by raising awareness of TIO, and taking into consideration the accessibility and variability of different healthcare infrastructures. By recognizing the challenges associated with the diagnosis and treatment of TIO and by applying a stepwise approach with clear clinical practice guidelines, patient care and outcomes will be improved in the future.

Tumor-induced osteomalacia - a mystery illness beyond aches, pains, and depression

Objective. Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by chronic hypophosphatemia and osteomalacia. We present case of a patient with a protracted clinical course of TIO. TIO profoundly affected every aspect of his life with subsequent profound physical and psychosocial disabilities. Method. The review of a complex clinical presentation, serial laboratory investigations, and imaging modalities of a patient with TIO caused by a mesenchymal tumor. Results. The patient presented with chronic lower back pain, severe bilateral leg weakness, and multiple pathological fractures due to severe osteoporosis. His investigations revealed hypophosphatemia, low 1,25 dihydroxyvitamin D, phosphaturia and normal serum calcium, and parathyroid hormone. Elevated fibroblast growth factor 23 (FGF23) confirmed the diagnosis of TIO and ⁶⁸Ga-DOTATATE-positron emission tomography/computed tomography (PET/CT) imaging correctly identified a tumor in the left femoral head. His clinical features and biochemical abnormalities promptly recovered after successful surgical resection of the mesenchymal tumor. Conclusion. The present case demonstrated the need to extensively investigate causes of generalized bone pain in patients with hypophosphatemia, as TIO is highly curable. Importantly, ⁶⁸Ga-DOTATATE PET/CT imaging successfully identified the FGF23 producing tumor, which was undetectable by conventional imaging, favoring its early use in suspected TIO presentation. The present report highlights the importance of timely diagnosis of this complex medical condition, aiming to improve general awareness and enable better clinical outcomes for this rare disorder.

Malignant phosphaturic mesenchymal tumor-ossifying fibroma-like subtype: a case report and literature review

BACKGROUND

A phosphaturic mesenchymal tumor (PMT) is classified into four histological subtypes: mixed connective tissue, osteoblast-like, non-ossifying fibroma-like, and ossifying fibroma-like. The ossifying fibroma-like subtype being extremely rare. Most PMTs are benign, with a minimal number becoming malignant after recurrence. In this study, we report a case of recurrence and malignant transformation of PMT-ossifying fibroma-like subtype in the left hip bone.

CASE PRESENTATION

Here, we report the clinical manifestations, histology, pathological features, and treatment of a 57-year-old Chinese woman with a recurrent and malignant ossifying fibroma-like subtype PMT of the left iliac bone. The tumor was first discovered 3 years ago when the patient underwent surgery to remove the tumor. Precisely 2 years and 6 months after the operation, the pain in the left hip reappeared. After 6 months, the patient went to our hospital for treatment. After the tumor resection, the postoperative symptoms improved significantly, and the serum alkaline phosphatase level returned to normal. Based on clinical manifestations, evaluation of serum biochemical indicators, X-ray examination, computerized tomography scan of the pelvis, and histopathological examination of the two operations, the patient was finally diagnosed with a recurring and malignant transformation of the left iliac bone phosphaturic mesenchymal tumor-ossifying fibroma-like subtype. No tumor recurrence was found during the follow-up 15 months after the operation.

CONCLUSIONS

This case increases the awareness of a rare malignant subtype of PMT and provides a valuable reference for the diagnosis of this disease.

Management of intrathoracic phosphaturic mesenchymal tumor by nonintubated uniportal video-assisted thoracic surgery in a fragile patient

Background

Phosphaturic mesenchymal tumors are rare neoplasms, frequently presenting with osteomalacia. These neoplasms usually grow at a slow rate and are associated with unspecific symptoms.

Case

In this study, we present the case of a 70‐year‐old woman who had been suffering from musculoskeletal pain, hypophosphatemia, and spontaneous fractures. Positron emission tomography with Gallium showed increase uptake in a subpleural lesion.

Conclusion

The patient underwent surgical excision of the subpleural lesion with a non‐intubated uniportal video‐assisted thoracoscopic surgery approach.

Oncogenic osteomalacia secondary to glomus tumor

SUMMARY

Oncogenic osteomalacia secondary to glomus tumor is extremely rare. Localization of causative tumors is critical as surgical resection can lead to a complete biochemical and clinical cure. We present a case of oncogenic osteomalacia treated with resection of glomus tumor. A 39-year-old woman with a history of chronic sinusitis presented with chronic body ache and muscle weakness. Biochemical evaluation revealed elevated alkaline phosphatase hypophosphatemia, increased urinary phosphate excretion, low calcitriol, and FGF23 was unsuppressed suggestive of oncogenic osteomalacia. Diagnostic studies showed increase uptake in multiple bones. Localization with MRI of paranasal sinuses revealed a sinonasal mass with concurrent uptake in the same area on the octreotide scan. Surgical resection of the sinonasal mass was consistent with the glomus tumor. The patient improved both clinically and biochemically postoperatively. Along with the case of oncogenic osteomalacia secondary to a glomus tumor, we have also discussed in detail the recent development in the diagnosis and management of oncogenic osteomalacia.

LEARNING POINTS

Tumor-induced osteomalacia is a rare cause of osteomalacia caused by the secretion of FGF23 from mesenchymal tumors. Mesenchymal tumors causing TIO are often difficult to localize and treat. Resection of the tumor can result in complete resolution of biochemical and clinical manifestations in a very short span of time. Glomus tumor can lead to tumor induced osteomalacia and should be surgically treated.

The phosphaturic mesenchymal tumor as a cause of oncogenic osteomalacia. Three cases and review of the literature

INTRODUCTION

The phosphaturic mesenchymal tumour (PMT) is a very uncommon cause of oncogenic osteomalacia (OO), which is a paraneoplastic syndrome with severe clinical osteomalacia. The PMT is a neoplasia that produces the fibroblast growth factor FGF23, resulting in reduced proximal tubular phosphate reabsorption leading to hyperphosphaturia and hypophosphatemia. Our aim is to present our experience and complications in diagnosis and treatment of PMT in three patients.

MATERIAL AND METHODS

We propose an observational, descriptive and retrospective study of three cases of OO secondary to PMT found in our database of bone and soft tissue tumours. The inclusion criteria were: symptoms related with OO, presence of hyperphosphaturic hypophosphatemia, elevated levels of FGF23 in blood and pathological diagnosis of PMT.

RESULTS

In all cases, the disease showed asthenia, non-specific bone pain, progressive functional weakness, and pathological fractures. The average delay time in diagnosis was 7 years. All presented with hyperphosphaturic hypophosphatemia, elevated levels of alkaline phosphatase as well as FGF23. The use of Octreoscan and PET-CT were essential to find the producing tumour and its subsequent biopsy. Treatment was surgery in two cases and one case was treated by CT-guided cryotherapy with neurophysiological control. Once the surgery was performed, the blood parameters normalized. There is no recurrence.

CONCLUSIONS

Phosphaturic mesenchymal tumor is a very rare entity as part of bone and soft tissue tumors, it may occur in both tissues. The phosphate-calcium homeostasis is altered due to high serum levels of FGF23 because of PMT. Delay in diagnosis is usual, leading to renal and skeletal comorbidities. To avoid this, knowledge of this entity together with high diagnostic suspicion are critical. Surgical treatment leads to normalization of serum levels and systemic symptoms.

Application of ultrasound-guided biopsy and percutaneous radiofrequency ablation in 2 cases with phosphaturic mesenchymal tumor and literature review

Tumor-induced osteomalacia (TIO) is a vanishingly rare paraneoplastic syndrome which is usually caused by phosphaturic mesenchymal tumors (PMTs). The conventional treatment for PMTs is total resection, and ultrasound-guided radiofrequency ablation (RFA) can also be used for the treatment of PMTs patients, especially for patients in whom complete resection may lead to serious complications. We report two cases with PMT who presented syndrome with progressive musculoskeletal complaints and performed ultrasound-guided biopsy and RFA. Ultrasound-guided RFA, which is a safe and effective minimally invasive treatment option, appears to be a valuable alternative to surgery for patients presenting with PMT. We are the first reported case of RFA guided by ultrasonography in the treatment of PMT.

Interim Analysis of a Phase 2 Open-Label Trial Assessing Burosumab Efficacy and Safety in Patients With Tumor-Induced Osteomalacia

Patients with tumor-induced osteomalacia (TIO), an acquired paraneoplastic condition characterized by osteomalacia due to hypophosphatemia, exhibit a similar clinical picture to those with X-linked hypophosphatemic rickets/osteomalacia (XLH). The human monoclonal anti-fibroblast growth factor 23 (FGF23) antibody burosumab (KRN23) increases serum phosphate and improves bone turnover, fracture healing, pain, and physical function in XLH patients by inhibiting circulating FGF23; thus, burosumab is expected to be an effective treatment for TIO. We report here an interim analysis of a multicenter, open-label, intraindividual dose-adjustment study of burosumab (0.3 to 2.0 mg/kg every 4 weeks) in Japanese and Korean TIO patients. The primary endpoint was the fasting serum phosphate level at each visit. Key secondary endpoints were changes over time in bone biomarkers, pharmacodynamic markers, bone histomorphometric parameters, motor function, and patient-reported outcomes. Safety was assessed based on treatment-emergent adverse events (TEAEs). Thirteen patients received burosumab treatment, of whom 4 underwent bone biopsy. The mean dose after week 112 was approximately 1.0 mg/kg. After the first burosumab administration, mean serum phosphate levels increased and remained above the lower limit of normal and in the normal range from weeks 14 to 112. Bone biomarkers initially increased, reaching maximum values at week 16 or 24, and then gradually decreased. After burosumab treatment, patients were able to walk further (evaluated by the 6-minute walk test), reported decreased pain levels, and showed a tendency toward healing of baseline fractures and pseudofractures. Two patients discontinued, one each due to disease progression and consent withdrawal. Burosumab was generally well tolerated, with no treatment-related TEAEs of grade ≥3 and no treatment-related serious AEs. In conclusion, the interim results of this first study of burosumab to treat TIO patients indicate that this drug has the potential to provide clinical benefit for patients with unresectable tumors. The full study results are eagerly anticipated. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..

Nasal hemangiopericytoma presenting with oncogenic osteomalasia: A case report and literature review

Sinonasal type hemangiopericytoma is a rare soft tissue tumor. Oncogenic osteomalacia (tumor-induced osteomalacia) is a rare syndrome that develops especially due to benign mesenchymal tumors. Nonspecific general bone pain and weakness delay the diagnosis and treatment of oncogenic osteomalacia, and it is difficult to determine the localization of the primary tumor causing oncogenic osteomalacia. A 43-year-old male patient with nasal hemangiopericytoma with symptoms of oncogenic osteomalacia is presented. The patient had musculoskeletal complaints at first and was diagnosed with lumbar disc herniation and surgery was performed. When his complaints recurred 1 year later, he was re-evaluated and diagnosed with hypophosphatemic osteomalacia. Despite the various treatments he received, his complaints did not decrease but increased, so a detailed examination was decided. When the positive PHEX mutation and very high fibroblast growth factor 23 level were detected, PET-CT imaging was performed with a pre-diagnosis of possible oncogenic osteomalacia, but no finding was found. Then he was evaluated with Ga-68 DOTATATE, and the soft tissue mass filling the right ethmoidal sinus was detected. Due to the relation of the mass with surrounding structures, it was considered unsuitable for total excision and incomplete surgical excision was performed. Pathologic evaluation revealed sinonasal type hemangiopericytoma (glomangiopericytoma). A significant remission in the patient's complaints was observed after the operation. Young patients with osteomalacia with unknown causes should be evaluated for malignancy, and screening and further examinations should be performed.

Performance of 68Ga-DOTA-SST PET/CT, octreoscan SPECT/CT and 18F-FDG PET/CT in the detection of culprit tumors causing osteomalacia: a meta-analysis

Objectives

The objective of this study was to assess and compare the performance of ⁶⁸Ga-DOTA-conjugated-somatostatin-receptor-targeting-peptides (⁶⁸Ga-DOTA-SST) PET/CT, octreoscan-SPECT/CT and ¹⁸F-FDG-PET/CT in the detection of tumor-induced osteomalacia (TIO).

Methods

Relevant studies reporting the performance ⁶⁸Ga-DOTA-SST PET/CT, octreoscan-SPECT/CT and ¹⁸F-FDG-PET/CT in TIO were identified by searching PubMed, EMBASE, and Web of Science (last updated June 2019). Two authors independently extracted the numbers of true and false positives, and true and false negatives. The pooled estimates on a per-patient basis were calculated with 95% confidence interval (CI) obtained using a random-effects model.

Results

Fourteen studies comprising 346 patients were included in this meta-analysis. The meta-analysis provided the following results on a per-patient analysis. The pooled sensitivities of both ⁶⁸Ga-DOTA-SST PET/CT (90%, 95% CI 82–95%) and octreoscan-SPECT/CT (83%, 95% CI 75–89%) were found to be significantly higher (P < 0.005) than that of ¹⁸F-FDG PET/CT (67%, 95% CI 53–80%). There was no statistically significant difference between the sensitivity of ⁶⁸Ga-DOTA-SST PET/CT and octreoscan-SPECT/CT (P = 0.161). Owing to the low number of articles with true negative findings, the pooled specificities were not calculated. A total of 287 tumors were identified in 287 patients according to the data the included studies offered. The majority of the tumors were located in the lower extremities (59.6%, 171/287), followed by craniofacial regions (24.0%, 69/287), torso (9.4%%, 27/287), and upper extremities (6.9%, 20/287).

Conclusion

This meta-analysis demonstrates that somatostatin receptor-based imaging modalities outperformed ¹⁸F-FDG PET/CT in the detection of TIO, with ⁶⁸Ga-DOTA-SST PET/CT performing slightly better than octreoscan-SPECT/CT.

Tumor-Induced Osteomalacia

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by tumoral production of fibroblast growth factor 23 (FGF23). The hallmark biochemical features include hypophosphatemia due to renal phosphate wasting, inappropriately normal or frankly low 1,25-dihydroxy-vitamin D, and inappropriately normal or elevated FGF23. TIO is caused by typically small, slow growing, benign phosphaturic mesenchymal tumors (PMTs) that are located almost anywhere in the body from the skull to the feet, in soft tissue or bone. The recent identification of fusion genes in a significant subset of PMTs has provided important insights into PMT tumorigenesis. Although management of this disease may seem straightforward, considering that complete resection of the tumor leads to its cure, locating these often-tiny tumors is frequently a challenge. For this purpose, a stepwise, systematic approach is required. It starts with thorough medical history and physical examination, followed by functional imaging, and confirmation of identified lesions by anatomical imaging. If the tumor resection is not possible, medical therapy with phosphate and active vitamin D is indicated. Novel therapeutic approaches include image-guided tumor ablation and medical treatment with the anti-FGF23 antibody burosumab or the pan-FGFR tyrosine kinase inhibitor, BGJ398/infigratinib. Great progress has been made in the diagnosis and treatment of TIO, and more is likely to come, turning this challenging, debilitating disease into a gratifying cure for patients and their providers.

Hiding in plain sight: Gene panel and genetic markers reveal 26-year undiagnosed tumor-induced osteomalacia of the rib concurrently misdiagnosed as X-linked hypophosphatemia

Tumor-induced osteomalacia (TIO), caused by phosphaturic mesenchymal tumors (PMTs), is a rare paraneoplastic syndrome characterized by frequent bone fractures, bone pain, muscle weakness, and affected gait. These tumors typically secrete high levels of Fibroblastic Growth Factor 23 (FGF23), a hormone which acts on the kidney to cause hypophosphatemia, ultimately impairing bone mineralization. In this case report, we present a 41-year-old female with FGF23-mediated hypophosphatemia with a 26-year delay in TIO diagnosis and a concurrent misdiagnosis of X-linked hypophosphatemic rickets (XLH). Given an absence of family history of hypophosphatemia, a 13-gene hypophosphatemia panel including XLH (PHEX gene) was performed and came back negative prompting a diagnostic search for a PMT causing TIO. A ⁶⁸Ga-DOTATATE PET/CT scan revealed the presence of a 9th right rib lesion, for which she underwent rib resection. The patient's laboratory values (notably serum phosphorus, calcium, and vitamin D) normalized, with FGF23 decreasing immediately after surgery, and symptoms resolving over the next three months. Chromogenic in situ hybridization (CISH) and RNA-sequencing of the tumor were positive for FGF23 (CISH) and the transcriptional marker FN1-FGFR1, a novel fusion gene between fibronectin (FN1) and Fibroblast Growth Factor Receptor 1 (FGFR1), previously determined to be present in the majority of TIO-associated tumors. This case demonstrates the notion that rare and diagnostically challenging disorders like TIO can be undiagnosed and/or misdiagnosed for many years, even by experienced clinicians and routine lab testing. It also underscores the power of novel tools available to clinicians such as gene panels, CISH, and RNA sequencing, and their ability to characterize TIO and its related tumors in the context of several phenotypically similar diseases.

Hypophosphatemic Hypovitaminosis D Induces Osteomalacia in the Adult Female Rat

Osteomalacia is a bone-demineralizing disease of adulthood, often caused by hypovitaminosis D. Current animal models of the disease mimic osteomalacia as a consequence of gastric bypass or toxic exposure to metals, but a relevant model of diet-induced osteomalacia is lacking. For that purpose, 7-month-old female Sprague Dawley rats were randomly assigned into 2 weight-stratified groups and maintained for 4 months on synthetic diets containing negligible or normal levels of vitamin D. The dietary regimen resulted in vitamin D deficiency as measured by 25-hydroxyvitamin D serum levels; however, hypovitaminosis D per se did not affect biomarkers of calcium metabolism and bone turnover, nor did it result in increased osteoid. Thus, vitamin D depletion through the diet was found to be insufficient to induce an osteomalacia-like phenotype in the adult rat. After 4 months, the phosphate content of the vitamin D-depleted diet had decreased to 0.16% (calcium:phosphorus ratio of 5.85), resulting in an osteomalacic-like condition (trabecular osteoid surface/bone surface constituted 33%; CI, 26-40). The diet change also affected both metabolic and bone turnover biomarkers, including significantly suppressing serum fibroblast growth factor 23. Furthermore, decreased dietary phosphate in a vitamin D-depleted diet led to microarchitectural changes of trabecular and cortical bone, lower bone mass density, lower bone mass content and decreased bone strength, all indicating reduced bone quality. Taken together, our results show that osteomalacia can be induced in the adult female rat by depleting vitamin D and lowering phosphate content in the diet.

Rheumatologische paraneoplastische Syndrome

Rheumatologische paraneoplastische Syndrome sind selten, stellten jedoch eine wichtige Differenzialdiagnose zu klassischen rheumatologischen Krankheitsbildern dar. Durch das Erkennen der eindrücklichen Syndrome mit typischen Labor- und Untersuchungsbefunden ist oftmals eine beschleunigte Diagnose der zugrundeliegenden Malignität und kurative Therapie möglich. In dieser Übersichtsarbeit werden die Charakteristika rheumatologischer paraneoplastischer Syndrome vorgestellt.

Combination of pembrolizumab and 125I attenuates the aggressiveness of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-associated mortality. Therapies targeting programmed cell death 1 ligand 1 (PD1L1) have promising effects on NSCLC. However, resistance to targeted therapy has become the main problem and the underling molecular mechanism remains unclear. In the present study, the expression of PD1L1 in NSCLC was determined and the association with clinicopathological characteristics was analyzed. A combination therapy was also constructed, including pembrolizumab (Pem) and iodine-125 (¹²⁵I), which represented an efficient strategy for the treatment of NSCLC. The expression of PD1L1 was upregulated in NSCLC tissues and positively correlated with the Ki-67 index, pathological subtypes and risk stages. A higher level of PD1L1 expression was associated with poorer survival in patients with NSCLC, which could be used as a prognostic indicator. When NSCLC cells were cultured in the presence of Pem and ¹²⁵I seeds, the combination treatment significantly abrogated the tumor proliferation and aggressiveness through the inhibition of matrix metalloproteinase-2 and -9 secretion. Flow cytometry analysis revealed pembrolizumab combined with ¹²⁵I contributed to a higher rate of apoptosis and cell cycle arrest, indicating that the combination treatment improved the resistance to immunotherapy. Furthermore, the associated molecular mechanism was the dysregulation of ADAM metallopeptidase domain 17. The findings from the present study revealed that PD1L1 could be used as a predictive biomarker, and the application of combination treatment of pembrolizumab and ¹²⁵I showed promising effects on NSCLC.

Oncogenic osteomalacia caused by a phosphaturic mesenchymal tumor of the femur: A case report

BACKGROUND

Oncogenic osteomalacia caused by phosphaturic mesenchymal tumors is very difficult to detect. We report a case of tumor-induced osteomalacia caused by a phosphaturic mesenchymal tumor of the left femur in a middle-aged woman after medical imaging and biopsy.

CASE SUMMARY

A 57-year-old woman presented with progressive bone pain for five years. She was diagnosed with hypophosphatemic osteomalacia, as her laboratory data showed low serum phosphorus and low serum calcium. Her knee joint radiography revealed an osteolytic lesion of the left femur. A computed tomography scan showed mixed density shadows in the left femur. Magnetic resonance imaging of the left femur showed the presence of an oval area with a hypointense signal in T1-weighted magnetic resonance imaging (MRI) and high-low mixed signal in T2-weighted MRI. Biopsy samples revealed the presence of short spindle cells, vascularization, and characteristics of phosphaturic mesenchymal tumors. Tumor resection was performed, and the clinical presentations and laboratory abnormalities were reversed.

CONCLUSION

Diagnosis of oncogenic osteomalacia is difficult due to the varieties and localization of source tumors and absence of pathognomonic biomedical signs. Our case highlights the importance of a combination of medical imaging and biopsy in the diagnosis of oncogenic osteomalacia caused by a phosphaturic mesenchymal tumor.

Metastatic prostate cancer presenting as tumour-induced osteomalacia

Tumour-induced osteomalacia (TIO), or oncogenic osteomalacia, is a paraneoplastic syndrome marked by hypophosphataemia, renal phosphate wasting, bone pain, weakness, and fractures. The syndrome has been reported with both benign and malignant tumours including parotid gland basal cell tumours, thyroid carcinomas, colon adenocarcinomas, and prostate cancer. Often, the syndrome is marked by an insidious course during which patients present with generalised bony pain and weakness, which do not resolve until the underlying tumour is identified and treated. We present a case of a patient with Parkinson's disease whose subacute weakness, lower extremity paresis, and renal phosphate wasting led to the synchronous diagnosis of metastatic prostate adenocarcinoma and TIO.

Phosphaturic mesenchymal tumors among elderly patients: a case report and review of literature

Phosphaturic mesenchymal tumor (PMT) represents a rare cause of osteomalacia. The clinical signs and symptoms are vague and these lead to diagnosis delay. In the presence of hypophosphatemia and relatively high urine phosphate excretion, this entity should be taken into consideration in the deferential diagnosis of osteomalacia. In the present article, we report 81-year-old man presented to our clinic for evaluation due to osteopenia. His laboratory results disclosed hypophosphatemia, relatively increased urine phosphate excretion and increased level of intact fibroblast growth factor 23 (FGF23). A 68Gallium DOTATATE PET/CT revealed pathological uptake in the upper aspect of the left shoulder adjacent to the coracoid process. For suspected PMT a wide resection of the tumor was performed and pathological findings were consistent for PMT. Laboratory tests were normalized postoperatively. Reviewing the literature, we had identified 33 reported cases of PMTs among elderly patients age ≥70 years. Unlike previously reported data, where tumors predominantly localized in the lower extremities and pelvis, our search disclosed a high rate of tumor localization (10 cases - 33.3%) in the head with equal number of tumors (14 cases - 42.4%) localized in the head and upper extremity as well as in pelvis and lower extremity. The present case describes unique tumor localization in an elderly patient and our literature search demonstrated for the first time a high rate of tumor localization in the head among this group of patients. Learning points: PMTs represent a rare entity that should be considered in the differential diagnosis of elderly patients presented with persistent hypophosphatemia. Unlike previously reported data, head and neck tumor localization is frequent among elderly patients. 68Gallium-conjugated somatostatin peptide analogs, such as 68Ga-DOTATATE PET/CT demonstrated the greatest sensitivity and specificity for tumor localization in patients with phosphaturic mesenchymal tumors (PMTs). Wide tumor resection using intraoperative ultrasound is of major importance in order to ensure long-term cure.

Paraneoplastic syndromes and other systemic disorders associated with neuroendocrine neoplasms

Neuroendocrine paraneoplastic syndromes (PNS) consist of metabolic disorders that accompany benign and malignant neoplasms but remain unrelated to mass effects or invasion by the primary tumor or its metastases. The underlying pathogenesis responsible for PNS usual clinical presentation relies on aberrant production of protein hormones, proteins and other substances by the tumor. Prompt recognition of characteristic signs and symptoms combined with serological identification of key substances may result in early diagnosis of PNS and its underlying malignancy. For these reasons, healthcare professionals should familiarize themselves with tumor-induced hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid syndrome, virilisation syndrome, gynecomastia, acromegaly, Cushing syndrome, osteogenic osteomalacia, tumor-induced hypoglycemia, necrolytic migratory erythema, and watery diarrhea, hypokalemia and achlorydria syndrome. Medical awareness for PNS can improve patient outcomes through earlier administration of cancer therapy and treatment, better symptomatic relief and prolong overall survival.

Tumor-induced osteomalacia: experience from three tertiary care centers in India

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by recalcitrant hypophosphatemia. Reports from the Indian subcontinent are scarce, with most being single center experiences involving few patients. Herein, we conducted a retrospective analysis of 30 patients of TIO diagnosed at three tertiary care hospitals in India. Patients with persistent hypophosphatemia (despite correction of hypovitaminosis D), normocalcemia, elevated alkaline phosphatase, low TmP/GFR and elevated or 'inappropriately normal' FGF23 levels were labeled as having TIO. They were sequentially subjected to functional followed by anatomical imaging. Patients with a well-localized tumor underwent excision; others were put on phosphorous and calcitriol supplementation. The mean age at presentation was 39.6 years with female:male ratio of 3:2. Bone pain (83.3%) and proximal myopathy (70%) were the chief complaints; 40% of cases had fractures. The mean delay in diagnosis was 3.8 years. Tumors were clinically detectable in four patients (13.3%). The mean serum phosphate was 0.50 mmol/L with a median serum FGF23 level of 518 RU/mL. Somatostatin receptor-based scintigraphy was found to be superior to FDG-PET in tumor localization. Lower extremities were the most common site of the tumor (72%). Tumor size was positively correlated with serum FGF23 levels. Twenty-two patients underwent tumor resection and 16 of them had phosphaturic mesenchymal tumors. Surgical excision led to cure in 72.7% of patients whereas disease persistence and disease recurrence were seen in 18.2% and 9.1% of cases, respectively. At the last follow-up, serum phosphate in the surgically treated group was significantly higher than in the medically managed group.

Sinonasal hemangiopericytoma caused hypophosphatemic osteomalacia: A case report

RATIONALE

Tumor-induced osteomalacia (TIO) is a rare, paraneoplastic syndrome featured with fibroblast growth factor 23 (FGF23) secretion primarily by benign mesenchymal tumors and sometimes by malignancies. TIO diagnosis and treatment is often delayed because TIO usually has nonspecific generalized bone pain and weakness, and location of TIO tumor is quite challenging. Very few TIO caused by sinonasal hemangiopericytoma have been reported in the literature.

PATIENT CONCERNS

A 40-year-old Chinese woman presented with diffuse bone pain for more than 1 year. Laboratory examination showed hypophosphatemia, hyperphosphaturia, hypocalcemia, an elevated serum alkaline phosphatase (ALP) level and bone-specific ALP level. Imaging studies revealed low bone mineral density (BMD) and multiple pseudofractures at the ribs. F-18 fluorodeoxyglucose positron emission tomography was negative in searching for tumors. Because no tumor was located, the patient was treated with oral phosphate, calcium, and alfacalcidol, and achieved great relief in her symptoms and improvement in BMD. Six years later, the patient had breast cancer surgery and received chemotherapy, and still had hypophosphatemia. During this time, nasopharyngo-fiberscope showed nasal mass in her left nasal cavity. Then she had her nasal polyps removed and surprisingly the serum phosphate became normal.

DIAGNOSES AND INTERVENTIONS

The patient had the nasal mass resected, and pathological diagnosis of the nasal mass was sinonasal hemangiopericytoma. Immunohistochemical analysis was positive for FGF23. Thus the final diagnosis was osteomalacia induced by sinonasal hemangiopericytoma. Phosphate supplementation and alfacalcidol were discontinued.

OUTCOMES

The patient had normal serum phosphate after 6-month follow-up.

LESSONS

By presenting this case, we hope to remind clinicians that in patients with osteomalacia with undetermined reason and intranasal polypoid mass, sinonasal hemangiopericytoma should be suspected.

Role of phosphate sensing in bone and mineral metabolism

Inorganic phosphate (P_i) is essential for signal transduction and cell metabolism, and is also an essential structural component of the extracellular matrix of the skeleton. P_i is sensed in bacteria and yeast at the plasma membrane, which activates intracellular signal transduction to control the expression of P_i transporters and other genes that control intracellular P_i levels. In multicellular organisms, P_i homeostasis must be maintained in the organism and at the cellular level, requiring an endocrine and metabolic P_i-sensing mechanism, about which little is currently known. This Review will discuss the metabolic effects of P_i, which are mediated by P_i transporters, inositol pyrophosphates and SYG1-Pho81-XPR1 (SPX)-domain proteins to maintain cellular phosphate homeostasis in the musculoskeletal system. In addition, we will discuss how P_i is sensed by the human body to regulate the production of fibroblast growth factor 23 (FGF23), parathyroid hormone and calcitriol to maintain serum levels of P_i in a narrow range. New findings on the crosstalk between iron and P_i homeostasis in the regulation of FGF23 expression will also be outlined. Mutations in components of these metabolic and endocrine phosphate sensors result in genetic disorders of phosphate homeostasis, cardiomyopathy and familial basal ganglial calcifications, highlighting the importance of this newly emerging area of research.

Phosphaturic mesenchymal tumor and related wound problem

INTRODUCTION

Phosphaturic mesenchymal tumor mixed connective tissue type (PMT/MCT) is the most common type (up to 90%) of phosphaturic mesenchymal tumor (PMT), a rare clinicopathologic entity. Besides overproduction of fibroblast growth factor 23 (FGF23), there is a big variation of immunohistochemical characteristic across types of PMT, which makes it difficult to obtain an early diagnosis of PMT/MCT. As a benign tumor, PMT/MCT usually happens in subcutaneous tissues and leads to nonhealing of wound. A complete excision of PMT/MCT facilitates wound healing.

CONCLUSIONS

Review of the existing evidence indicates that early diagnosis of PMT/MCT is critically important when treating PMT/MCT wound. Hence standardization of early diagnosis for PMT/MCT is mandated.

Successful Localization Using 68Ga-DOTATOC PET/CT of a Phosphaturic Mesenchymal Tumor Causing Osteomalacia in a Patient with Concurrent Follicular Lymphoma

Diagnosing tumor-induced osteomalacia is often challenging because conventional imaging modalities may fail to locate the responsible tumor. This report describes the ability of ⁶⁸Ga-DOTATOC PET/CT to successfully distinguish between the responsible phosphaturic mesenchymal tumor and concurrent lymphoma lesions. A 52-year-old man with bone pain for several years was diagnosed with a vitamin D-resistant hypophosphatemic osteomalacia. Whole body ¹⁸F-FDG PET/CT revealed multiple enlarged hypermetabolic lymph nodes in his bilateral cervical, axillary, mediastinal, abdominal, pelvic, and inguinal regions. Core needle biopsy of the right cervical lymph node confirmed the diagnosis of follicular lymphoma. However, lymphoma was not considered the cause of osteomalacia. ⁶⁸Ga-DOTATOC PET/CT before chemotherapy showed a small nodule with intensely increased uptake in the right inguinal region, which was distinguished from the other enlarged lymph nodes. The nodule was surgically removed and histopathologically consistent with phosphaturic mesenchymal tumor. After surgery, the patient's serum phosphorus and alkaline phosphatase levels normalized without nutritional supplement.

Clinical utility of bone markers in various diseases

Measurements of bone markers (BMs) in peripheral blood or urine are a pivotal part of bone research within modern clinical medicine. In recent years the use of BMs increased substantially as they can be useful either to diagnose bone (related) disease and to follow its natural history, but also to monitor the effects of interventions. However, the use of BMs is still complicated mainly due to (pre)analytical variability of these substances, limited accessibility of assays, variable cut-off values in different countries and laboratories and heterogeneous results with regard to clinical implications of measuring BMs in several studies. This review will provide the clinician with a practical guide, based on current evidence, in which circumstances to test which bone markers for optimal diagnostic purposes, in order to improve patient care in different areas of bone diseases including Paget's disease, primary osteoporosis, tumor induced osteomalacia, hypophosphatemic rickets, van Buchem disease, chronic kidney disease, rheumatoid arthritis, neoplasma/multiple myeloma, type 2 diabetes mellitus and primary hyperparathyroidism. The clinician should consider fasting state, recent fractures, aging, menopausal status, concomitant liver and kidney disease when ordering and interpreting BM measurements as these factors might result in misleading BM concentrations. We found that BMs are clearly useful in the current diagnosis of tumor induced osteomalacia, van Buchem disease, Paget's disease and hypophosphatemic rickets. In addition, BMs are useful to monitor disease activity in chronic kidney disease, Paget's disease and are useful to monitor treatment adherence in osteoporosis.

Distant lung metastases caused by a histologically benign phosphaturic mesenchymal tumor

Tumor-induced osteomalacia (TIO) is a rare form of hypophosphatemia usually caused by phosphaturic mesenchymal tumors (PMTs); the biologic behavior of PMTs is under investigation. Herein we present a case of TIO with a protracted course over 12 years leading to a fatal outcome. A 39-year-old man presented with weakness in 2004 and was found to have decreased serum phosphorus, phosphaturia and low levels of 1,25-dihydroxyvitamin D3. Four years later he developed a painful left calf mass. The lesion was resected, but recurred causing extreme pain and dysfunction. Radiological examination showed a large cluster of soft tissue tumors affecting all the muscle compartments of the calf and a smaller lesion inside the metaphysis of the tibia. Above-knee amputation was performed. Histological examination of all lesions showed a cellular spindle cell neoplasm with variously sized vessels, wide vessel-like spaces and scattered deposits of calcified extracellular material. The tumor infiltrated skeletal muscles, subcutaneous fat and the proximal end of the fibula. The tibial lesion had identical histology. Three years after the amputation the patient presented with cough and dyspnea. Radiological examination, followed by an open biopsy, showed that there were multiple metastatic nodules of PMTs in both lungs. Shortly after the diagnosis the patient died. This case illustrates that even benign cases of PMTs may lead to a fatal outcome and the classification of PMTs into benign and malignant should be reassessed in order to correspond to its biological behavior.