Phosphaturic mesenchymal tumor-induced bilateral osteomalacia femoral neck fractures: a case report.

Phosphaturic mesenchymal tumors (PMT) are rare and distinctive tumors that typically result in paraneoplastic syndrome known as tumor-induced osteomalacia (TIO). We report a case of bilateral osteoporotic femoral neck fracture caused by PMT. PMT was surgically resected, followed by sequential treatment of bilateral femoral neck fractures with total hip arthroplasty (THA). A 49-year-old perimenopausal woman experienced consistent bone pain with limb weakness persisting for over 2 years. Initially, she was diagnosed with early osteonecrosis of the femoral head and received nonsurgical treatment. However, from 2020 to 2022, her pain extended to the bilateral shoulders and knees with increased intensity. She had no positive family history or any other genetic diseases, and her menstrual cycles were regular. Physical examination revealed tenderness at the midpoints of the bilateral groin and restricted bilateral hip range of motion, with grade 3/5 muscle strength in both lower extremities. Laboratory findings revealed moderate anemia (hemoglobin 66 g/L), leukopenia (2.70 × 109/L), neutropenia (1.28 × 109/L), hypophosphatemia (0.36 mmol/L), high alkaline phosphatase activity (308.00 U/L), and normal serum calcium (2.22 mmol/L). After surgery, additional examinations were performed to explore the cause of hypophosphatemic osteomalacia. After definitive diagnosis, the patient underwent tumor resection via T11 laminectomy on August 6, 2022. Six months after the second THA, the patient regained normal gait with satisfactory hip movement function without recurrence of PMT-associated osteomalacia or prosthesis loosening. By providing detailed clinical data and a diagnostic and treatment approach, we aimed to improve the clinical understanding of femoral neck fractures caused by TIO.

Tumour-induced osteomalacia: the long road to diagnosis and recovery.

Tumour-induced osteomalacia is caused by tumorous production of fibroblast growth factor 23 (FGF23) leading to urinary phosphate wasting, hypophosphataemia and decreased vitamin D activation. The resulting osteomalacia presents with muscle weakness and bone pain but progresses to multiple pathological fractures. Patients often remain undiagnosed for years with severe physical, psychological and economic ramifications. A young woman presented with multiple spontaneous fractures including bilateral femoral fractures. Laboratory tests revealed severe hypophosphataemia, elevated bone turnover markers and low to normal calcium and 25-hydroxy-vitamin D levels. Treatment with phosphate, alfalcalcidol, calcium and magnesium was initiated. 68Gallium-DOTATOC positron emission tomography imaging revealed a mass in the right foot and venous sampling of FGF23 from all extremities confirmed this tumour as the culprit. Biopsy and histology were consistent with a phosphaturic mesenchymal tumour, which was surgically resected. Phosphate levels quickly normalised postoperatively but a long convalescence with hungry bone syndrome, fracture healing and physical therapy followed.

Treatment and Diagnose of Spinal Phosphaturic Mesenchymal Tumor: A Case Report and a Systematic Literature Review.

BACKGROUND: Spinal phosphaturic mesenchymal tumor (PMT) is a rare disorder but can be cured once the diagnosis is clear and a complete removal by surgery is performed. To the best of our knowledge, only 22 cases in the spine have been described, and we report a case with the largest number of spinal segments (T12-L5) affected among spine PMT cases. METHODS: A comprehensive literature search was performed until May 23, 2023, following the Preferred Reporting Items for Systematic Reviews guidelines. Studies were chosen through relevant PubMed, Web of Science, and EMBASE searches to prioritize obtaining the largest studies. The Medical Subject Headings and Boolean operators employed for this search were ("PMT" or "TIO" or "Tumor-induced osteomalacia" or "phosphaturic mesenchymal tumor") and ("spine" or "spinal"). Two researchers (L.S.Z. and D.B.C) independently reviewed and evaluated the included articles. Any differing opinions were discussed until a consensus was reached. A total of 18 studies were included. A case report is also presented. RESULTS: We report a case of spinal PMT. The full text of the relevant articles was construed. A total of 18 studies were reviewed and consolidated. These articles are roughly divided into the following 5 subcategories: 1) clinical features and baseline distribution, 2) laboratory and imaging findings, 3) pathological manifestations, and 4) surgical methods and treatment options. CONCLUSIONS: Spinal PMT is very rare with a high rate of misdiagnosis and debilitating complications, so it is of significance to increase awareness of the disease among spine surgeons consulted by patients with spinal PMT. 68Ga-DOTATOC-PET/CT shows very high sensitivity to the spinal PMT but there is no way to exactly determine the location of the tumor. PMT has unique immunohistochemical characteristics and malignant PMT is rare. Once diagnosed, complete surgical excision is the recommended treatment. Burosumab is one of the available options, especially in cases that are recurrent and difficult to surgically resect.

[FGF23 tumor induced osteomalacia with localization of neoplasm in the tympanic cavity]. / FRF23-indutsirovannaya osteomalyatsiya opukholevogo geneza s lokalizatsiei novoobrazovaniya v barabannoi polosti.

Tumor induced osteomalacia is a rare paraneoplastic syndrome caused by mesenchymal tumors that secrete fibroblast growth factor 23 (FGF23). Patients complain of progressive bone pain, muscle weakness and brittle fractures. Delayed diagnosis of osteomalacia caused by a tumor is often found in clinical practice. When verifying the exact localization of the neoplasm, radical removal within healthy tissues is recommended. The article considers a clinical example of FGF23 tumor induced osteomalacia with localization of neoplasm in the tympanic cavity.

[Clinical features, diagnostics and treatment of FGF23 secreting tumors: series of 40 clinical cases].

INTRODUCTION: Tumor-induced osteomalacia is an acquired rare disease manifested by hypophosphatemic osteomalacia due to excessive secretion of fibroblast growth factor 23 (FGF23). FGF 23 is a non-classical hormone secreted by bone tissue (osteocytes) and regulates phosphorus metabolism.The aim of this work is to present clinical experience in the diagnosis, treatment and rehabilitation of patients with tumor-induced osteomalacia. MATERIALS AND METHODS: 40 patients with clinically-confirmed tumor-induced osteomalacia were included in the study, 34 of whom had the tumor localized, 27 underwent surgical treatment and 21 achieved stable remission. RESULTS: The median age was 48 [41; 63] years, 43% were men, the time left from the the onset of the disease was 8 [4; 10] years. Biochemical findings were hypophosphatemia 0.47 [0.4; 0.53] mmol/l, a decrease in the tubular reabsorption phosphate 62 [52; 67]%, and an increase in alkaline phosphatase of 183 [112; 294] units/l. At the time of diagnosis, 100% had multiple pathological fractures, only 10% could move independently, and 77.5% classified the pain as unbearable (8-10 points according to the 10-point pain syndrome scale ). Among the methods used to detect tumors, the most sensitive were scintigraphy with tectrotide with SPECT/CT 71.4% (20/28) and MRI 90% (18/20). In 35% of cases, the tumor was localized in soft tissues and in 65% in bone tissue; The tumor was most often detected in the lower extremities, followed by the head in frequency of localization. 18 patients currently have no remission and they receive conservative treatment (phosphorus and alfacalcidol n=15 and burosumab n=3). In case of achieving remission (n=21), regression of clinical symptoms and restoration of bone and muscle mass was observed. Extensive excision of the tumor without prior biopsy resulted in the best percentage of remission - 87%. CONCLUSION: Tumor-induced osteomalacia is characterized by severe damage to bone and muscle tissue with the development of multiple fractures, muscle weakness and severe pain syndrome. In laboratory diagnostics, attention should be paid to hypophosphatemia, a decrease in the tubular reabsorption phosphate index and increased alkaline phosphatase. The use of functional diagnostic methods with a labeled somatostatin analogue to the subtype 2 receptor and MRI with contrast enhancement are the most accurate methods of topical diagnostics. In case of localization of the tumor, a wide excision without a preliminary biopsy is recommended.

Phosphaturic mesenchymal tumor: A chondromyxoid fibroma-like type.

Phosphaturic mesenchymal tumor (PMT) is a rare neoplasm that causes tumor-induced osteomalasia (TIO) in most affected patients, usually through the production of fibroblast growth factor 23 (FGF23). This tumor is often misdiagnosed due to its relative rarity and its widely varied histomorphologic spectrum. Here we describe a case of a 78-year-old woman who presented with a left middle tumor without symptoms of TIO. The histological features resembled chondromyxoid fibroma with smudgy calcification in the tumor matrix. In addition, we evaluated FGF23 expression through immunohistochemical study and reverse transcription polymerase chain reaction. PMT with chondromyxoid fibroma features are extremely rare. Examining the expression of FGF23 is useful in the diagnosis of PMT.

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.

A Phosphaturic Mesenchymal Tumor Presenting as Reversible Metabolic Myopathy.

Tumor-induced osteomalacia (TIO) is a disorder in which the clinical signs and symptoms of osteomalacia and the biochemical abnormalities of hypophosphatemia, phosphaturia, and low serum levels of 1,25(OH)2 Vitamin D3 are secondary to a neoplasm. A 33-year-old woman presented with musculoskeletal pain and proximal myopathy with a duration of 2.5 years which was treated with Vitamin D supplements. On the basis of the biochemical tests and histopathology, she was reevaluated and found to have TIO secondary to a phosphaturic mesenchymal tumor. The tumor was resected (limb salvage with endoprosthesis), and she had no pain or weakness at followup. The case reminds the readers to consider the possibility of TIO when evaluating patients with isolated hypophosphatemia, which may lead to long-term disability and prolonged morbidity if untreated. Early recognition and diagnosis of TIO is crucial since resection of the tumor usually reverses its manifestations.

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 Challenges in Diagnosis, Tumor Localization and Treatment of Tumor-Induced Osteomalacia: Outcome of a Retrospective Surveillance.

Tumor-induced osteomalacia (TIO) is an acquired fibroblast growth factor 23 (FGF23)-related hypophosphatemic osteomalacia caused by phosphaturic mesenchymal tumors (PMTs) developed in the bone or soft tissue. Diagnostic delay should be addressed, and ideal techniques to localize PMTs and efficient treatment options should be explored to improve the outcomes of this rare disease. To clarify the detailed clinical course and outcomes of TIO patients, retrospective questionnaire surveys were conducted among physicians from the Japanese Society for Bone and Mineral Research (JSBMR) and the Japan Endocrine Society (JES). The primary survey collected the number of TIO patients between January 2007 and December 2018. The secondary survey aimed to obtain the detailed characteristics, laboratory data, and outcomes. Eighty-eight patients (52 males, mean: 52 years old) were included, and 24 patients were clinically diagnosed with TIO without localized PMTs. The median duration from the onset to detection of high FGF23 levels was 3.4 years, with 77 patients being initially misdiagnosed. Among the methods used to detect small, localized PMTs (≤10 mm), fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography and somatostatin receptor scintigraphy were less sensitive than somatostatin receptor positron emission tomography/computed tomography (SRPET/CT). Systemic venous sampling (SVS) of FGF23 was performed in 53 patients; among them, SVS was considered useful for detecting localized PMTs in 45 patients with diverse tumor sizes. Finally, 45 patients achieved biochemical remission by surgery, 39 patients continued pharmaceutical treatment, including burosumab (11 patients), and four patients died. These results encouraged us to further increase the awareness of TIO and to improve the accessibility of SRPET/CT and SVS. Further evidence about the efficacy of new pharmaceutical treatments is awaited. © 2022 American Society for Bone and Mineral Research (ASBMR).

Tumor-induced osteomalacia: a case report.

BACKGROUND: Tumor-induced osteomalacia is a rare, acquired paraneoplastic syndrome, including hypophosphatemia, high serum alkaline phosphatase, reduced active vitamin D, suboptimal bone mineral density, bone pain, fragility fractures, and muscle weakness. CASE PRESENTATION: We report a case of 74-year-old male of mixed ancestry with hypophosphatemia resistant to treatment despite optimal compliance, associated with profound reduction of bone mineral density and multiple nontraumatic fractures, including bilateral rib fractures, lower-thoracic (T11, T12) vertebrae, and two fractures involving the surgical and anatomical neck of the right humerus. We discuss an approach to identifying the underlying cause of hypophosphatemia associated with fragility fractures, and options for management of this rare condition. CONCLUSION: Although rare, tumor-induced osteomalacia can be diagnosed if a logical stepwise approach is implemented. Surgery could be curative if the tumor is properly located and is resectable.

Phosphaturic Mesenchymal Tumor of the Ankle: A Case Report and Review of the Literature.

We report the case of a phosphaturic mesenchymal tumor of the ankle; an extremely rare lesion that causes osteomalacia via paraneoplastic renal phosphate wasting. A 41-year-old man was referred to plastic surgery with a swelling over the anterior ankle, which had been increasing in size for 1 year. Focused ultrasound assessment was inconclusive, but excision biopsy demonstrated features in keeping with a phosphaturic mesenchymal tumor. Evidence of tumor-induced osteomalacia was subsequently identified on review of historical biochemistry. The patient was followed-up for 1 year with normalization of serum phosphate. In this case report, we present a discussion of the differential diagnosis for foot and ankle soft tissue lesions, and a review of the literature regarding the diagnosis and management of these tumors. Accurate identification of any soft tissue lesion on clinical examination alone is extremely challenging and excision biopsy should be considered in cases of diagnostic uncertainty.

[Diagnosis and surgical treatment of sinonasal phosphaturic mesenchymal tumor].

Objective: To investigate the diagnosis and surgical treatment of sinonasal phosphaturic mesenchymal tumor (PMT). Methods: The medical records of nine patients who had been diagnosed as sinonasal PMT in Department of Otorhinolaryngology Head and Neck Surgery, Shanghai JiaoTong University Affiliated Sixth People's Hospital between January 2015 and May 2020 were collected, including 4 males and 5 females, ranging from 36 to 59 years. The patient's previous history, clinical manifestations, imaging findings, laboratory results, surgical procedure, pathological results and postoperative follow-up data were analyzed by descriptive statistical analysis. Results: All patients presented hypophosphatemia and tumor-induced osteomalacia (TIO) with a disease course of 1 to 19 years. The imaging examination and intraoperative findings identified two cases with peripheral tissue infiltration, two cases with contralateral nasal cavity invasion, and one case with intracranial invasion. Five patients underwent unilateral endoscopic resection while two patients underwent bilateral endoscopic resection, and the remaining two patients underwent unilateral transorbital ethmoid artery ligation plus endoscopic tumor resection and endoscopic combined with transfrontal tumor resection (n=1 each). Expect for one case developed recurrence and intracranial involvement, the other patients achieved clinical remission and no recurrence was observed during the six-month follow-up. Conclusions: The diagnosis of sinonasal PMT needs combination of clinical manifestation, imaging, and pathological findings. Complete surgical excision and long-term postoperative follow-up are imperative.

Persistent phosphaturic mesenchymal tumor causing tumor-induced osteomalacia treated with image-guided ablation.

Phosphaturic mesenchymal tumors (PMTs) can present with vague symptoms of diffuse bone pain with pathologic fractures that often lead to a delayed diagnosis. We present a 60-year-old patient with a PMT that was persistently hypophosphatemic after resection, who was then successfully treated with cryoablation of the tumor. Tumor-induced osteomalacia (TIO) is a rare cause of hypophosphatemia characterized by vague symptoms of gradual muscle weakness and diffuse bone pain with pathologic fractures that often lead to a delayed diagnosis. This condition is usually caused by benign phosphaturic mesenchymal tumors (PMTs). Here, we present a case of persistent PMT after surgical resection treated with image-guided ablation. We present the patient's clinical examinations and laboratory findings (phosphorus, 1,25 (OH)2D, FGF-23, Intact PTH). Representative histologic images of a PMT are also presented. A 61-year-old male was evaluated for persistent hypophosphatemia and presumed osteomalacia. Six years earlier, he underwent surgical excision of a left ischial mass after presenting with TIO. The pathology was consistent with a PMT; however, hypophosphatemia persisted suggesting incomplete resection. He was treated with calcitriol and phosphate salts. A PET Ga68 dotatate scan of the patient revealed an avid left ischial mixed lytic and sclerotic lesions with marked amount of radiotracer uptake, suggesting persistent tumor. The patient was resistant to re-excision of the tumor due to the extended recovery period from his prior surgery and was treated instead with cryoablation of the tumor. His biochemical findings of hypophosphatemia and elevated FGF23 resolved after the ablation and have remained normal for 5 months after surgery. In patients with TIO, wide surgical excision is the treatment of choice. When this is not possible, image-guided ablation is an alternative therapeutic option.

Subcutaneous seeding following surgical excision of an intracranial meningioma in a cat.

Traditionally patient owners express their concerns that surgical or diagnostic procedures on a tumor may induce metastasis. In pets, this has been documented in only very rare occasions, e. g. needle path metastases after diagnostic fine needle biopsies of urinary bladder or prostatic tumors. Here, we describe a case of subcutaneous seeding of a feline intracranial grade 1 meningioma 6 months after surgical resection. A 10-year-old male neutered domestic shorthaired cat with typical neurological signs was diagnosed with an extra-axial contrast enhancing mass in the dorsal frontotemporal lobes using magnetic resonance imaging (MRI). Transfronto-parietal bone craniotomy was performed and the 24 × 19 × 22 mm large tumor was largely removed. Tumor recurrence after 12 months resulted in a second surgical tumor removal. In addition, 2 subcutaneous masses of 10 × 4 × 4 mm in size were removed at the site of the original surgical site which were fully separated from the recurring meningeal tumor by the intact frontal bone. Histology and immunohistochemistry suggested the same tumor growth in all 4 masses. Most likely the tumor seeding had been caused during the first surgery. After all, the risk of surgical seeding of a benign tumor seems very low.

Surgical margin for phosphaturic mesenchymal tumors in soft tissues: An analysis of the radiological histopathological correlation.

BACKGROUND: Phosphaturic mesenchymal tumors primarily cause tumor-induced osteomalacia, a rare paraneoplastic syndrome, and half occur in soft tissues. There are few reports about the surgical margins of these tumors. This study aimed to clarify the optimal surgical margin for phosphaturic mesenchymal tumors by analyzing radiological and histopathological features. METHODS: This study included eight cases, seven primary and one recurrent, of tumor-induced osteomalacia caused by soft-tissue phosphaturic mesenchymal tumors that were surgically treated between January 2000 and January 2019. We evaluated the radiological and histopathological features of all tumors and investigated the correlation of these features, the surgical margin, and recurrence of hypophosphatemia. RESULTS: The tumors were located in superficial (n = 5) and deep (n = 3) tissues. Six of the eight tumors had a clear boundary, but five had an irregular margin. Three tumors had a hypointense rim on T2-weighted images, indicating fibrous tumor encapsulation. Histopathological analysis revealed infiltrative growth in six of the eight tumors, which correlated with an irregular margin seen on imaging. Although there was no recurrence in patients treated with an intended wide margin >1 cm, one of the three patients treated with marginal tumor resection experienced a recurrence of hypophosphatemia, with histopathological analysis showing infiltration of subcutaneous fat. In contrast, two tumors with clear boundaries, regular margins, and fibrous capsule seen on imaging, had no infiltrative growth and were cured by marginal resection. In one recurrent case, tumor infiltration was observed in the previous surgical scar, which was not detected on preoperative imaging. CONCLUSIONS: Soft-tissue phosphaturic mesenchymal tumors with an irregular boundary seen on imaging tend to be infiltrative, especially into subcutaneous fat, and should be treated by at least a 1-cm wide margin resection. Tumors with a fibrous capsule with clear and regular margins are cured by marginal margin resection. These findings could inform surgeons' decisions regarding the resection of soft-tissue phosphaturic mesenchymal tumors.

Infantile Myofibroma: Case Report and Review of the Literature.

We report a case of solitary infantile myofibroma (IM) with partially CD34-positive neoplastic cells on the back of a newborn boy. Ultrasonography showed a multilocular mass with a hypoechoic center surrounded by an isoechoic rim. Histopathological analysis revealed that the lesion was composed of small, round cells that were tightly packed and uniform. The cells had oval nuclei and were pale, CD34-positive, and richly cellular. They had interlacing fascicles of spindle cells with features of myofibroblasts with α-smooth muscle actin positivity. We speculate that neoplastic cells in most IMs differentiate towards myofibroblasts. However, in rare cases, their differentiation is more primitive and they express CD34, with or without α-smooth muscle actin expression.

Conjunctival Stromal Tumor: Report of 2 New Cases and Review of the Literature.

Conjunctival stromal tumor (COST) is an emerging entity with only a limited number of cases reported in the literature. In this report, we describe 2 additional cases, review the accumulative clinical and histopathological features and expand on the immunophenotypic property of this entity. COST appears to have a sporadic presentation, affecting both sexes and patients of variable ethnicity and age group and predominantly occurring on the bulbar conjunctiva as a slow-growing asymptomatic or slightly tender mass-like lesion. Histopathologically, COST is characterized by singly dispersed spindle to round cells, often with some degree of degenerative nuclear atypia, within a myxomatous to collagenous stroma. Lesional cells are characteristically positive for CD34 and vimentin, negative for S100, SOX10 and STAT6 and show a normal pattern of staining with RB1 by immunohistochemistry. The reported cases to date have shown an indolent biological behavior, reliably treated by a complete surgical excision.

Prognostic Value of Positive Presurgical FDG PET/CT in the Evaluation of Tumor-Induced Osteomalacia.

METHODS: Seventy-six patients who had surgically removed tumors that caused osteomalacia were included in this retrospective investigation. All patients underwent both 18F-FDG and 68Ga-DOTATATE PET/CT prior to surgery. The prognostic value of presurgical FDG PET/CT study was determined with 5-year follow-up. RESULTS: In the presurgical evaluation, 68Ga-DOTATATE detected lesions in all 76 patients. However, FDG PET/CT was positive in only 25 among all 76 patients. Following surgical removal of the causative tumor, all 76 patients had symptomatic relief and normalization of the serum phosphate level initially. However, 15 of 76 cases (19.7%) had recurrent hypophosphatemia and became symptomatic again during the follow-up. Among these 15 patients with recurrence, 11 (73.3%) had recurrent lesions at the original location of the resected causative tumors, whereas 4 were in other locations due to malignant nature of the primary tumor. Interestingly, 14 of these 15 patients with recurrent disease had positive presurgical FDG PET/CT findings with an incident ratio of 56.0% (14 of 25). In contrast, only 1 patient with recurrent disease had negative presurgical FDG PET/CT scan with an incident ratio of 1.9% (1 of 51), significantly less than the positive presurgical FDG PET/CT group (P < 0.05). CONCLUSIONS: A positive presurgical FDG PET/CT suggests increased likelihood for possible recurrence of TIO after surgical resection. In contrast, when a causative tumor detected by 68Ga-DOTATATE PET/CT does not have elevated activity on FDG PET/CT, the chance of recurrence is very small.