Intracranial Extraskeletal Mesenchymal Chondrosarcoma

BACKGROUND

Intracranial extraskeletal mesenchymal chondrosarcomas (MCSs) are rare tumors accounting for <0.16% of intracranial tumors. They are usually described as occurring in the age group of 20-30 years and are commonly found in the frontoparietal region arising from the falx and surrounding dura. We describe 3 cases at varying ages, locations, and outcomes.

CASE DESCRIPTION

A 42-year-old woman with anterior one third falx-based lesion; a 7-year-old boy with mid one third falcine lesion with hyperostosis of bone, presenting in comatose stage; and a 52-year-old woman with left posterior lateral frontal dural-based lesion are presented. Histopathology of all cases was confirmed with immunohistochemistry. All patients underwent complete excision but had varying outcomes.

CONCLUSIONS

Intracranial MCSs are rare malignant tumors with poor prognosis. Because of their rarity, it may not be considered as a differential diagnosis and it is often misdiagnosed radiologically, but the importance lies in the need of radical excision. The potential effect of postoperative radiotherapy and chemotherapy is controversial. This article sheds some light on variable prognosis of this tumor.

Hemangiopericytoma of the Cerebellopontine Angle: A Wolf in Sheep's Clothing

Primary meningeal hemangiopericytoma (HPC) is a rare, aggressive dura based tumor that remarkably mimics a meningioma clinically and radiologically. Its occurrence within the cerebellopontine angle (CPA) is exceptional, and establishing the exact diagnosis is of the utmost importance since total resection remains the cornerstone of treatment. A 42-year-old man presented with a three-month history of progressively worsening vertigo and difficulty in walking. On admission, his neurological examination revealed a right peripheral facial palsy, right abducens palsy and left hemiparesis, suggesting the diagnosis of Millard-Gubler syndrome. Computed tomography and magnetic resonance imaging demonstrated a homogeneously enhancing dura based lesion of the right CPA causing major brain stem compression. There was no widening of the ipsilateral internal auditory canal. A standard retrosigmoid craniotomy was performed to access the right CPA. Exposure of the lesion revealed a well-encapsulated, gray, fibrous lesion, which appeared to originate from the tentorium. Gross total resection was achieved and confirmed radiologically. The microscopic features and the immunohistochemical profile confirmed the diagnosis of a HPC, and adjuvant radiation therapy was administered. Ten years later, the patient presented with a severe neurological deficit due to a local recurrence, but at that time refused any second intervention. He died three months later. HPC can locate within the CPA and present as a Millard-Gubler syndrome. The diagnosis should be kept in mind in case of a CPA dura based tumor. Radical surgery plus radiation therapy can maximize the recurrence-free survival and close follow-up remains mandatory to spot recurrences early.

Solitary fibrous tumor of the greater omentum mimicking an ovarian tumor in a young woman

We report a case of solitary fibrous tumor (SFT) of greater omentum in a young woman. SFT arising from the greater omentum can mimic a gynecologic neoplasm. SFTs are generally benign but some of them are malignant and have uncertain prognosis. An adequate follow-up is essential in these patients.

Activation of multiple angiogenic signaling pathways in hemangiopericytoma

Hemangiopericytoma (HPC) is a highly vascularized mesenchymal tumor. Local recurrence and distant metastasis are common features of HPC. Considering the remarkable hyper-vasculature phenotype of HPC, we assumed that dysregulated angiogenic signaling pathways were involved in HPC. The key components of angiogenic signaling pathways including VEGF-VEGF-R2, EphrinB2-EphB4 and DLL4-Notch were examined by real-time RT-PCR, Western blotting and immunostaining in 17 surgical specimens of HPC patients and in 6 controls. A significant upregulation of VEGF and VEGF-R2 associated with elevated levels of p-Akt and proliferating cell nuclear antigen (PCNA) was detected in HPC. Moreover, a dramatic increase in the mRNA and protein expression of EphB4 and its downstream factor p-Erk1/2 was found in HPC. A massive activation of core-components of DLL4-Notch signaling was detected in HPC. Double-immunofluorescent staining confirmed the expression of these upregulated key factors in the endothelial cells of tumor vessels. The present study identified the activation of multiple and crucial angiogenic signaling pathways, which could function individually and/or synergistically to stimulate angiogenesis in HPC and eventually contribute to tumor growth and progression. Our findings emphasize the importance to target multiple angiogenic signaling pathways when an anti-angiogenic therapy is considered for this highly vascularized tumor.

Update on Select Benign Mesenchymal and Meningothelial Sinonasal Tract Lesions

Several benign and malignant mesenchymal and meningothelial lesions may preferentially affect or extend into the sinonasal tract. Glomangiopericytoma (GPC, formerly sinonasal-type hemangiopericytoma) is a specific tumor with a predilection to the sinonasal tract. Sinonasal tract polyps with stromal atypia (antrochoanal polyp) demonstrate unique histologic findings in the sinonasal tract. Juvenile nasopharyngeal angiofibroma (JNA) arises from specialized tissue in this location. Meningioma may develop as direct extension from its intracranial counterpart or as an ectopic tumor. Selected benign mesenchymal tumors may arise in the sinonasal tract and pose a unique differential diagnostic consideration, such as solitary fibrous tumor and GPC or lobular capillary hemangioma and JNA. Although benign and malignant vascular, fibrous, fatty, skeletal muscle, and nerve sheath tumors may occur in this location, this paper focuses on a highly select group of rare benign sinonasal tract tumors with their clinicopathological and molecular findings, and differential diagnosis.

Intraventricular Hemangiopericytoma: A Case Report and Literature Review

BACKGROUND

Hemangiopericytomas are rare intracranial neoplasms that generally occur in the fifth decade of life and are commonly dural-based, supratentorial tumors. They are classified as World Health Organization grade II or III because of their aggressive nature with high rates of local recurrence and distant metastasis. This case is of an intraventricular hemangiopericytoma in a 23-year-old man. Intraventricular locations are rare, with only 10 cases reported in the literature. Our patient is the youngest to be diagnosed with an intraventricular hemangiopericytoma outside a pediatric case discovered at autopsy.

CLINICAL PRESENTATION

A 23-year-old man with a left intraventricular hemangiopericytoma presenting with headache, word-finding difficulties, blurred vision, nausea, vomiting, photophobia, and right-sided weakness and numbness. Using a left superior parietal lobule approach, a piecemeal resection was completed, achieving radiographic gross total resection. Pathology was consistent with a hemangiopericytoma. He was treated adjunctively with 60 Gy of local radiation. At 6-month follow-up, the patient had resolution of his aphasia and improvement in his headaches, with no signs of recurrence or metastasis on imaging.

CONCLUSIONS

Standard treatment for central nervous system hemangiopericytoma includes aggressive surgical resection. The role of adjuvant radiation is less well defined but is commonly pursued postoperatively. Regardless of extent of resection or adjuvant treatment, close follow-up to evaluate for evidence of local recurrence and distant metastasis is essential.

Anaplastic hemangiopericytoma in the frontal horn of the lateral ventricle

Intracranial hemangiopericytomas are uncommon tumors, and their intraventricular occurrence is even rarer. We report a 40-year-old man who presented with raised intracranial pressure. His MRI showed a 3.3 × 3.2 × 3.2 cm heterogeneously enhancing lesion in the left frontal horn obstructing the foramen of Monro and causing hydrocephalus. The tumor was excised through an anterior interhemispheric, transcallosal approach, and histopathology revealed an anaplastic hemangiopericytoma (World Health Organization grade III). To our knowledge this is the first report of this rare pathology being located within the frontal horn of the lateral ventricle.

Meningeal Solitary Fibrous Tumors with Delayed Extracranial Metastasis

BACKGROUND

The term solitary fibrous tumor (SFT) is preferred over meningeal hemangiopericytoma (HPC), because NAB2-STAT6 gene fusion has been observed in both intracranial and extracranial HPCs. HPCs are now considered cellular variants of SFTs.

METHODS

This study analyzes 19 patients with STAT6-confirmed SFTs, who were followed for over 11 years in a single institution. Ten patients (10/19, 56.2%) had extracranial metastases (metastatic group), while the remainder (9/19) did not (non-metastatic group). These two groups were compared clinicopathologically.

RESULTS

In the metastatic group, the primary metastatic sites were the lungs (n = 6), bone (n = 4), and liver (n = 3). There was a mean lag time of 14.2 years between the diagnosis of the initial meningeal tumor to that of systemic metastasis. The median age at initial tumor onset was 37.1 years in the metastatic group and 52.5 in the non-metastatic group. The 10-year survival rates of the metastatic- and non-metastatic groups were 100% and 33%, respectively. The significant prognostic factors for poor outcomes on univariate analysis included advanced age (≥45 years) and large initial tumor size (≥5 cm). In contrast, the patients with higher tumor grade, high mitotic rate (≥5/10 high-power fields), high Ki-67 index (≥5%), and the presence of necrosis or CD34 positivity showed tendency of poor prognosis but these parameters were not statistically significant poor prognostic markers.

CONCLUSIONS

Among patients with SFTs, younger patients (<45 years) experienced longer survival times and paradoxically had more frequent extracranial metastases after long latent periods than did older patients. Therefore, young patients with SFTs require careful surveillance and follow-up for early detection of systemic metastases.

Endoscopic transnasal approach for orbital tumors: A report of four cases

Endoscopic transnasal approach is an excellent technique for resecting orbital tumors located inferiorly and/or medially to the optic nerve. The aim of this study was to present four cases of orbital tumor which were, at least in part, resected by an endoscopic transnasal approach and to discuss both indications and limitations of this approach through a comparison of the location and tumor status, including the pathology, of these cases. In two cases with orbital tumor located in a medial-inferior quadrant, we were able to resect it only by an endoscopic transnasal approach. Because we experienced transient diplopia and dyschromatopsia after resecting intraconal tumors, a careful choice for the best approach is suggested in view of the location, size and properties of the tumor. In the third case, with tumor located in an inferior-lateral quadrant, it was eventually resected using a frontal-zygomatic approach because the medial and inferior borders of the tumor could not be identified and the lateral border was beyond the limits of manipulation by an endoscopic transnasal approach. In the last case with possible malignant tumor adhered to the lateral vital, the tumor was resected using a transantral approach. Based on these experiences, we introduce the indications for an endoscopic transnasal resection of orbital tumors.

Treatment Strategy of Intracranial Hemangiopericytoma

Background

Recent studies suggest aggressive management combining a grossly total resection (GTR) with adjuvant radiotherapy (RT) as a treatment of choice for intracranial hemangiopericytoma (HPC). However, in these papers, the definitions of complete or GTR are equivocal. In the present study, we reviewed the relevant cases from our experience focused on the clinical efficacy of surgical grading of resection, and analyzed the optimal treatment strategies as well.

Methods

From January 1995 through December 2014, 17 patients treated for intracranial HPC were included in this study. We analyzed clinical presentation, radiologic appearance, pathologic diagnosis, extent of resection, and follow-up outcomes.

Results

A total of 26 operations were performed including 9 recurrent intracranial HPCs. Every tumor was single and had no evidence of metastasis. Most common area of tumor was parasagittal (8 patients, 47.1%), which is adjoined to superior sagittal sinus. For the initial operation, GTR was performed in 16 cases (61.5%), partial resection (PR) in 8 cases (30.8%), and an endoscopic biopsy in 2 patients (7.7%). In Simpson grading system, grade 1 was done in 2 patients (7.7%), grade 2 in 11 patients (42.3%) and grade 3 in 3 patients (11.5%). Postoperative RT was delivered in 16 patients (94.1%) regardless of the extent of resection. The median 57.57 Gy (range, 50-60 Gy) was delivered in median 33 fractions (range, 30-40). The extent of resection (conventional classification and Simpson grading system) and adjuvant RT were significantly associated with recurrence-free survival.

Conclusion

Surgical resection of intracranial HPC, in an attempt to reach Simpson grade 1 removal, is necessary for better outcome. Adjuvant RT should be done as recommended before, to prevent recurrence, regardless of surgical resection and pathological diagnosis.

Metachronous Malignant Solitary Fibrous Tumor of Kidney: Case Report and Review of Literature

Solitary fibrous tumors are well described in the pleura, but rare extra-pleural neoplasms have been reported. We describe a patient with a solitary left renal fibrous tumor who after undergoing a nephrectomy, presented 8 years later with a contralateral metachronous solitary fibrous tumor. Malignant metastatic extra-pleural solitary fibrous tumors are extremely rare, and to our knowledge, this is the first case of contralateral recurrence of solitary renal fibrous tumor. The patient underwent a robotic assisted partial nephrectomy of the right renal mass. Both tumors showed overlapping histopathology.

The pericyte antigen RGS5 in perivascular soft tissue tumors

Perivascular soft tissue tumors are relatively uncommon neoplasms of unclear lineage of differentiation, although most are presumed to originate from or differentiate to pericytes or a modified perivascular cell. Among these, glomus tumor, myopericytoma, and angioleiomyoma share a spectrum of histologic findings and a perivascular growth pattern. In contrast, solitary fibrous tumor was once hypothesized to have pericytic differentiation--although little bona fide evidence of pericytic differentiation exists. Likewise the perivascular epithelioid cell tumor (PEComa) family shares a perivascular growth pattern, but with distinctive dual myoid-melanocytic differentiation. RGS5, regulator of G-protein signaling 5, is a novel pericyte antigen with increasing use in animal models. Here, we describe the immunohistochemical expression patterns of RGS5 across perivascular soft tissue tumors, including glomus tumor (n = 6), malignant glomus tumor (n = 4), myopericytoma (n = 3), angioleiomyoma (n = 9), myofibroma (n = 4), solitary fibrous tumor (n = 10), and PEComa (n = 19). Immunohistochemical staining and semi-quantification was performed, and compared to αSMA (smooth muscle actin) expression. Results showed that glomus tumor (including malignant glomus tumor), myopericytoma, and angioleiomyoma shared a similar diffuse immunoreactivity for RGS5 and αSMA across all tumors examined. In contrast, myofibroma, solitary fibrous tumor and PEComa showed predominantly focal to absent RGS5 immunoreactivity. These findings further support a common pericytic lineage of differentiation in glomus tumors, myopericytoma and angioleiomyoma. The pericyte marker RGS5 may be of future clinical utility for the evaluation of pericytic differentiation in soft tissue tumors.

Laparoscopic resection of intra-abdominal metastasis from intracranial hemangiopericytoma

INTRODUCTION

Hemangiopericytoma (HPC) is a rare mesenchymal tumor derived from capillary and postcapillary pericytes that often has an indolent course and occasionally presents with abdominal metastasis.

PRESENTATION OF CASE

Twenty-three years after the initial resection of an intracranial HPC located in the right frontoparietal region and left lateral ventricle, a 63-year-old man experienced dull abdominal pain and early satiety and had a palpable epigastric mass. Computed tomography indicated a suspected metastasis of HPC to the left upper abdomen. On laparoscopic exploration, the tumor was found in the falciform ligament and was excised laparoscopically per request of the patient. He had a fast recovery and experienced good relief of his pain and satiety. The patient had 2 additional metastases at his 12-month follow-up, both in the right retroperitoneum, and he again underwent laparoscopic resection. At his next annual follow-up, new metastases were identified in his liver, small-bowel mesentery, and peritoneal surface, prompting a trial of systemic chemotherapy. Because of progress of a left lower abdominal preperitoneal metastasis on follow-up at 3 years, the patient underwent a further successful laparoscopic exploration. Postoperatively, systemic chemotherapy was maintained.

DISCUSSION

We report the recurrent laparoscopic resection of peritoneal metastases of primary intracranial HPC with good symptom control and fast recovery. Both the patient and the referring physician requested a minimally invasive surgical approach.

CONCLUSION

Laparoscopic resection is a feasible treatment strategy for intraperitoneal metastases and is effective in symptom palliation.

Distinctive Characteristic Features of Intramedullary Hemangiopericytomas

Study Design

The retrospective analysis of intramedullary hemangiopericytomas (HPCs) was performed, and the entity was discussed in accordance with the literature findings.

Purpose

This study aimed at defining distinctive characteristic features of intramedullary HPC with respect to surgical approach and prognosis.

Overview of Literature

Intramedullary HPCs are extremely rare tumors. They originate from capillary pericytes, supposedly follow the vessels over the spinal cord, and infiltrate deep into the spinal cord without a distinct plane. Their treatments and prognosis are not well-defined in the literature.

Methods

Our database was retrospectively reviewed for the cases of HPCs. Later on, a literature search was performed to reveal all reported cases of intramedullary HPCs. The following key words were searched in PubMed databases: "hemangiopericytoma and intramedullary," "hemangiopericytoma and spine (spinal) and intradural," and "hemangiopericytoma and spinal cord." The articles were reviewed for patients' demographics features, imaging characteristics, tumor-specific factors (surgical technique, pathological descriptions, and world health organization grades), and postoperative course and prognosis (adjuvant therapies, recurrences, complications, and mortalities).

Results

A total of seven patients (three male and four female) was reached, with their ages ranging from 15 to 80 years (mean, 32.5 years). The tumors were located majorly in thoracic region (5/7, 71.4%), and only two cases were in the cervical region (2/7, 28.6%). All tumors were completely removed, and only two cases received radiotherapy. No recurrence was reported.

Conclusions

Complete resection of the intramedullary HPCs seems to be the best management strategy for long-term and recurrence-free survival and in alleviating further need for radiotherapy.

Lipomatous hemangiopericytoma in a child: A case report with immunohistochemical evaluation

Lipomatous hemangiopericytomas are rare soft-tissue tumors that show areas of hemangiopericytoma like vascular pattern admixed with lipid containing cells. It is now considered a subtype of solitary fibrous tumor due to histopathological and immunohistochemical similarities. To date, only a few cases have been adequately reported in the medical literature. A case of lipomatous hemangiopericytoma in an 11-year-old female patient is presented and the clinical, histopathological and immunohistochemical features are discussed, along with a literature review. To the best of our knowledge, this is the first known case of a lipomatous hemangiopericytoma in a pediatric patient. Our case report further emphasizes that a number of studies should be evaluated to delineate hemangiopericytomas from solitary fibrous tumors.

[Hemangiopericytoma of the cerebellopontine angle: case report and review of literature]

Les hémangiopéricytomes primitifs du système nerveux central sont rares et représentent moins de 1% des tumeurs intracraniennes. La localisation au niveau de l'angle ponto-cerebelleux est très rare, pouvant simuler un neurinome de l'acoustique ou un méningiome. Le diagnostic de certitude est basé sur l’étude histologique et immunohistochimique. Notre but est d'illustrer avec une revue de la littérature les aspects clinico-radiologiques, anatomopathologiques et la prise en charge thérapeutique de ce type de lésion.

Head and neck solitary fibrous tumors: a rare and challenging entity

The objective of this study is to analyze the outcome of treatment for solitary fibrous tumors (SFTs) in the head and neck area. SFTs present as slow-growing masses, often with local compressive symptoms that are difficult to distinguish from other soft-tissue tumors. SFTs are commonly treated using local excision without adjuvant therapy. To date, only heterogeneous small series have been published, documenting the treatment results and outcome with these tumors. Retrospective study of patients with histopathologically confirmed SFT treated at two tertiary referral hospitals between 2004 and 2014. Eight men and four women with histologically confirmed SFT were identified in the records. Their age range was 37-82 years (mean 57.8 years). The mean follow-up period for eight patients was 6.75 years (range 1-24 years). Four patients were lost to follow-up. Sublocalizations were neck (n = 3), orbit (n = 2), paranasal sinus (n = 2), cheek (n = 2), hard palate (n = 1), parotid gland (n = 1), and tongue (n = 1). The first-line treatment for all of the tumors identified was surgical excision. In four cases, the surgical margins were narrow or unclear due to piecemeal resection in the paranasal sinus and orbit (n = 3) or a tumor location deep in the parapharyngeal space (n = 1). Recurrences developed in two of these cases (in the orbit and parapharyngeal space), and the other two patients were lost to follow-up. Radiotherapy and chemotherapy were not administered as first-line treatments. Overall, the local recurrence rate (n = 2/8) was 25 %. The disease-specific survival rate was 100 %. These results are consistent with the literature data and show that safe surgical excision, without opening of the tumor capsule, reduces the risk of local recurrence and leads to a favorable outcome. Tumors in the head and neck often represent a surgical challenge, and wide surgical margins are rarely possible due to the complex three-dimensional anatomic compartments in the region. Head and neck surgeons should therefore be aware that there is an increased risk of recurrence in these patients; tightly scheduled follow-up visits are mandatory for at least 10 years, if not longer. Radiotherapy only appears to be an option in patients with unresectable tumors or when wide surgical excision would cause severe functional morbidity.

NAB2-STAT6 fusion gene analysis in two cases of meningeal solitary fibrous tumor/hemangiopericytoma with late distant metastases

We present two cases of meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) with immunohistochemistry of STAT6 and analysis of NAB2-STAT6 fusion genes. Case 1 was a 37-year-old male with a left middle fossa tumor; case 2 was a 68-year-old female with a cerebellar tumor. They showed late metastasis to the lung or bone 8 or 13 years, respectively, after the first surgery. Histology of both primary and metastatic tumors showed a cellular hemangiopericytomatous pattern with nuclear atypia. The primary tumors showed nuclear staining of STAT6, but both metastatic tumors showed nuclear and cytoplasmic STAT6. DNA sequencing revealed two kinds of NAB2-STAT6 fusion genes. One consisted of exon 6 of NAB2, intron 6 of NAB2, and the middle of exon 17 of STAT6 (observed in the primary and metastatic tumors of case 1); the other consisted of exon 6 of NAB2 and the beginning of exon 17 of STAT6 (observed in the metastatic tumor of case 2). The primary tumor of case 2 had both fusion genes. To the best of our knowledge, we are the first to report NAB2-STAT6 fusion gene analysis in primary and metastatic meningeal SFT/HPCs and a case showed different fusion gene status in the metastatic tumor.

Solitary lung metastasis from intracranial hemangiopericytoma 18 years after initial resection

We report a 29-year-old woman who presented with severe headache, nausea and vomiting. A lesion was found in the left petrous ridge and near-total resection was performed. Pathologic examination showed anaplastic hemangiopericytoma (World Health Organization Grade III). Hemangiopericytoma is an uncommon mesenchymal tumor that rarely occurs in an intracranial location. Prior studies have reported a surprisingly high rate of late recurrence and extracranial metastases from intracranial hemangiopericytomas, including metastases to the lungs. Resection was followed by external beam radiation. The tumor recurred intracranially 6 and 13 years later and was treated with gamma knife stereotactic radiosurgery. At year 14, she noticed a lump in her neck and underwent parotidectomy for a mucoepidermoid carcinoma. This new diagnosis prompted a staging chest CT scan which showed a 4mm right upper lobe lung nodule along with additional < 5 mm indeterminate nodules. Over the next 3 years, the nodule increased to 8mm. Wedge biopsy of the lung nodule showed metastatic hemangiopericytoma, histologically similar to the intracranial hemangiopericytoma. Both the primary and the lung metastasis were positive for CD34 and STAT-6. To the best of our knowledge, this is the longest reported interval between a resected intracranial hemangiopericytoma and a histologically confirmed solitary metastasis to the lung.

Multimodal treatment and management strategies for intracranial hemangiopericytoma

Intracranial hemangiopericytoma (HPC) is a rare malignant meningothelial tumor. The authors retrospectively reviewed the long-term clinical outcomes of patients with HPC with regard to treatment modalities and histopathological grades. Eighteen women and 20 men (mean age 38.5 years, range, 18-62 years) were observed over an average follow-up period of 61 months (range, 15-133 months) between 2003 and 2013. The initial treatment modalities included total tumor resection followed by conventional radiotherapy (RT) (n=27), and subtotal tumor resection followed by stereotactic radiosurgery (n=11). One patient (3%) had permanent neurological deficits, and six patients (16%) died. Thirteen patients (34%) suffered recurrence. One year, 5 year, and 10 year recurrence-free survival rates were 100%, 70%, and 39%, respectively. Five patients (13%) developed metastasis. One year, 5 year, and 10 year metastasis-free survival rates were 100%, 89%, 74%, respectively. Low grade tumors were associated with longer overall survival, recurrence-free interval and metastasis-free interval (log-rank, p<0.05). Radical resection with RT was associated with longer overall survival and recurrence-free interval (log-rank, p<0.05), but had no effect on the metastasis-free interval (log-rank, p=0.245). Thus, radical surgery followed by adjuvant RT is the primary treatment of HPC, but recurrence and metastasis remain a common treatment outcome regardless of initial strategy. It is necessary to maintain long-term follow-up and serial imaging for all patients with intracranial HPC after treatment, regardless of extent of resection.

Successful use of pazopanib for treatment of refractory metastatic hemangiopericytoma

Hemangiopericytoma is a rare disease entity of soft-tissue sarcoma (STS) that can be cured with surgical resection. In cases of inoperable recurrence or metastasis, palliative chemotherapy is indicated, though there is currently no approved chemotherapy regimen. Therefore new treatment regimens are needed.

We describe three cases of metastatic hemangiopericytoma. In the first case, five lines of chemotherapeutic agents were used unsuccessfully in a patient with a 12-year history of metastatic hemangiopericytoma. After one cycle of pazopanib therapy, however, chest radiography showed a decrease in tumor volume of more than 30%. A marked decrease in FDG uptake on PET CT was also noted, and the patient is now on her 5^th month of pazopanib therapy. The second case is a patient with a brain hemangiopericytoma with multiple liver, lung, and bone metastases. Pazopanib induced radiologic stabilization of metastatic disease over the course of 8 months. The third case is a patient with a retroperitoneal hemangiopericytoma with pleural and peri-renal metastases. For more than 8 months, he has exhibited stable disease with pazopanib treatment.

Pazopanib may be useful for treatment of metastatic hemangiopericytoma, though further studies are needed to confirm the efficacy of this medication and to investigate its molecular mechanism of action.

Regression of dural arteriovenous fistulae after venous flow reconstructive surgery in a case with hemangiopericytoma at the confluence of sinuses

Background

The mechanism by which acquired dural arteriovenous fistula (dAVF) develops is still unclear. Few cases have been reported with both dAVF and intracranial tumors, and in these few cases the authors have proposed that induced venous hypertension may lead to the pathogenesis of dAVF. We experienced a case of intrasinusoidal hemangiopericytoma (HPC) with dAVF development. In addition to its rare pathology and tumor location, this case showed regression of dAVF immediately after tumor removal.

Case Report

The patient was a 23-year-old man who developed progressively worse headaches and papilledema. The HPC was located entirely inside the confluence of the sinuses (CoS) and resulted in venous sinus occlusion. Cerebral angiography demonstrated a dAVF located in the straight sinus, upstream of the occluded CoS, which was fed by the dural branch of the posterior cerebral artery. After the endovascular embolization of the tumor feeders, subsequent surgery included venous reconstruction in addition to tumor excision. Although the dAVF was not treated with an endovascular procedure or surgery, postoperative angiography revealed complete disappearance of the dAVF.

Conclusion

We conclude that venous reconstructive surgery greatly contributed to the immediate regression of the dAVF. When planning the treatment strategy for such cases, it should be remembered that acquired dAVF may regress due to the normalization of venous hypertension.

Recurrent hypoglycemia triggered by sorafenib therapy in a patient with hemangiopericytoma

Targeted therapy has been proven to be one of the most effective cancer treatments. However, some endocrine disorders can occur during treatment with targeted agents. We report the case of a patient who exhibited a wax and wane pattern of hypoglycemia that was attributed to sorafenib therapy. A 32-year-old woman with metastatic hemangiopericytoma visited the emergency department in a stuporous state. Nonhyperinsulinemic hypoglycemia was diagnosed, was exacerbated shortly after sorafenib therapy, and was improved by the cessation of sorafenib with additional glucocorticoid therapy. Patients with metastatic hemangiopericytoma should be carefully monitored with particular attention to hypoglycemia when sorafenib therapy is initiated.

Sinonasal glomangiopericytoma causing oncogenic osteomalacia

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