Anaplastic meningioma versus meningeal hemangiopericytoma: Immunohistochemical and genetic markers

Intracranial solitary fibrous tumors: Clinical, radiological, and histopathological insights along with review of literature

BACKGROUND

Intracranial solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms, often challenging to diagnose due to their resemblance to meningiomas and other central nervous system tumors. While advancements in molecular genetics have aided in classification, diagnostic nuances and optimal management strategies remain areas of interest.

MATERIALS AND METHODS

This retrospective study analyzed 11 cases of intracranial SFTs treated at a neurosurgical centre in India between February 2020 and January 2024. Clinical data, radiological findings, histopathological features, and follow-up details were reviewed. Immunohistochemistry, particularly STAT6, facilitated diagnosis confirmation.

RESULTS

The median age of presentation was 32 years, with a male predominance. Headache was the most common presenting symptom, often leading to misdiagnosis as meningiomas on radiological imaging. Histologically, SFTs exhibited spindle to ovoid cells with staghorn vessels and collagenized stroma, posing challenges in differential diagnosis. WHO grading predominantly revealed grade 1 tumors, though recurrence occurred, emphasizing the importance of long-term follow-up. Immunohistochemistry, particularly STAT6, played a pivotal role in distinguishing SFTs from other entities.

CONCLUSION

Intracranial SFTs present diagnostic challenges due to overlapping features with other tumors, warranting a comprehensive approach integrating clinical, radiological, and histopathological findings. Immunohistochemistry, particularly STAT6, emerges as a valuable diagnostic tool. Long-term follow-up is essential for monitoring recurrence and potential malignant transformation. Further research is needed to delineate optimal treatment strategies, including the role of radiotherapy in SFT management.

Solitary Fibrous Tumor of the Central Nervous System: A Report of Two Cases with Emphasis on Diagnostic Pitfalls

Solitary fibrous tumor (SFT) is a rare primary central nervous system neoplasm that usually presents as a dural-based mass. Awareness of the entity is limited by the rarity of the tumor which renders it prone to misdiagnosis. We present two cases of SFT located in the right parafalx and intraventricular region. The cases were classified as WHO grade 1 and grade 2, respectively. The present study discusses the radiological, histomorphological, and immunohistochemical features of SFT, with emphasis on potential diagnostic pitfalls that may lead to erroneous diagnosis.

Cerebral Hemangiopericytoma Manifesting as Epilepsia Partialis Continua: A Case Report

Cerebral hemangiopericytomas are very rare mesenchymal tumours arising from pericytes surrounding the blood vessels in the brain. Most patients present with headaches, focal neurological findings and focal seizures with or without generalisation. Our patient chiefly complained of an uncontrollable movement of her right hand that was initially fleeting but later became continuous. Her symptoms were initially described as tremors. We found an intracranial tumour as a cause of her symptoms, suspected the tumour to be a meningioma and performed surgical extirpation which resulted in symptom resolution. Histopathology and immunohistochemistry of the excised mass revealed that the tumour was hemangiopericytoma. The patient is being closely monitored for recurrences and metastasis. Hemangiopericytomas are very rare and they rarely result in the abnormal movements of epilepsia partialis continua. Differentiation of the abnormal movements of epilepsia partialis continua from tremors is very important as is the differentiation of the tumour from meningioma.

Keywords

case reports; epilepsia partialis continua; hemangiopericytoma; solitary fibrous tumors.

An institutional review of 10 cases of spinal hemangiopericytoma/solitary fibrous tumor

Background

Spinal hemangiopericytoma is very rare tumors with only a few case reports and one case series. We have treated ten patients between 2004 and 2017 and, thus, present a retrospective review of our patients with a focus on clinical presentation, radiological features, management, pathology, and outcome.

Materials and Methods

Histopathological data were reviewed in all the cases and clinical and follow-up details were collected from data available in our department.

Results

There were five males and five females, including one pediatric patient. The mean age of the patients was 34.7 years (Range 12-52 years). Dorsal, cervical, and lumbar spine involvement were found in five, four, and one patient, respectively. Intradural extramedullary tumor was the most common tumor and all patients presented motor weaknesses. Gross total resection of the tumor was done in seven patients and six patients received postoperative radiotherapy. Histopathology showed anaplastic tumor in two cases with high MIB-1 labelling index. Most patients were positive for CD34, vimentin, mic-2, and bcl-2. While the seven patients who underwent gross total resection improved significantly and were self-ambulatory in the follow-up period, two patients who underwent subtotal resection expired due to tumor metastasis.

Conclusion

Spinal hemangiopericytoma is a very rare tumor. We present a series of cases treated at our institute for the same. Gross total resection is the goal and radiotherapy should be given in case of residual tumor or high-grade tumors. Prognosis is good after gross total excision and functional recovery can be expected in most patients.

Grade III meningioma with gastro-intestinal tract and brain metastases: case report and review of the literature

BACKGROUND

Meningioma is the most common adult primary intracranial tumor. Malignant meningioma is a rare variant of meningioma. The prognosis for the patients with these tumors is poor, due to the tumor's capacity for relapse and to develop distant metastases. These tumors can present the same evolutionary course as aggressive carcinoma.

CASE DESCRIPTION

We report the case of distant brain and gastro-intestinal tract (GIT) metastases. A 78-year-old patient developed malignant meningioma with a Ki-67 proliferative index of 40%. According to guidelines, surgery followed by postoperative radiotherapy (RT) was performed. Three months after the end of RT, he presented histologically proven meningioma distant brain and GIT metastases.

CONCLUSIONS

To our knowledge, this is the first case of meningioma GIT metastases. Also, we report the difficulty to confirm the diagnosis of meningioma metastases. Indeed, malignant meningioma has the same histopathological features as melanoma or carcinoma. The standard of care for the management of malignant meningioma is gross total surgery followed by postoperative radiotherapy. Metastatic meningioma is uncommon and no guidelines for the management of recurrent or metastatic meningioma have yet been published. However, several studies reported systemic therapeutic options such as antibody against VEGF, somatostatin analogs, PDGF-R, and VEGF-R tyrosine kinase inhibitors, in the case of recurrent or metastatic meningioma. We also made a review of the actual literature of systemic treatment options for metastatic meningioma.

CD99: A Cell Surface Protein with an Oncojanus Role in Tumors

The cell surface molecule CD99 has gained interest because of its involvement in regulating cell differentiation and adhesion/migration of immune and tumor cells. However, the molecule plays an intriguing and dual role in different cell types. In particular, it acts as a requirement for cell malignancy or as an oncosuppressor in tumors. In addition, the gene encodes for two different isoforms, which also act in opposition inside the same cell. This review highlights key studies focusing on the dual role of CD99 and its isoforms and discusses major critical issues, challenges, and strategies for overcoming those challenges. The review specifically underscores the properties that make the molecule an attractive therapeutic target and identifies new relationships and areas of study that may be exploited. The elucidation of the spatial and temporal control of the expression of CD99 in normal and tumor cells is required to obtain a full appreciation of this molecule and its signaling.

Value of SSTR2A and Claudin - 1 in Differentiating Meningioma from Schwannoma and Hemangiopericytoma

BACKGROUND:

The distinction between meningioma, schwannoma and solitary fibrous tumour/ hemangiopericytoma can be challenging in some cases. This study evaluates the expression of Somatostatin receptor 2A (SSTR2A) and Claudin-1 in these different tumours.

MATERIAL AND METHODS:

Thirty-five cases of meningioma, 10 cases of intracranial schwannoma and 10 cases of hemangiopericytoma were assessed. The immunohistochemical expression of SSTR2A and Claudin-1 was evaluated and scored according to the percentage of immunostained tumour cells (0: 1+, 2+ and 3). The intensity of staining was classified as weak, moderate and strong.

RESULTS:

Positivity for SSTR2A and Claudin-1 was encountered in 89% and 49% of meningiomas respectively. None of the schwannomas or hemangiopericytomas was positive for any of both markers. All grade I and II meningiomas were positive for SSTR2A, and only 20% of grade III showed positive staining (p < 0.05). Claudin-1 positivity was detected in 50%, 43% and 60% of grade I, II and III meningioma respectively, with significantly higher intensity in grade III (p < 0.05).

CONCLUSION:

SSTR2A is highly sensitive and specific for meningioma. Claudin-1 is highly specific for meningioma, with low sensitivity. The adjunctive use of both markers can be very helpful in the diagnosis of meningioma and its distinction from schwannoma and hemangiopericytoma.

CD99 at the crossroads of physiology and pathology

CD99 is a cell surface protein with unique features and only partly defined mechanisms of action. This molecule is involved in crucial biological processes, including cell adhesion, migration, death, differentiation and diapedesis, and it influences processes associated with inflammation, immune responses and cancer. CD99 is frequently overexpressed in many types of tumors, particularly pediatric tumors including Ewing sarcoma and specific subtypes of leukemia. Engagement of CD99 induces the death of malignant cells through non-conventional mechanisms. In Ewing sarcoma, triggering of CD99 by specific monoclonal antibodies activates hyperstimulation of micropinocytosis and leads to cancer cells killing through a caspase-independent, non-apoptotic pathway resembling methuosis. This process is characterized by extreme accumulation of vacuoles in the cytoplasmic space, which compromises cell viability, requires the activation of RAS-Rac1 downstream signaling and appears to be rather specific for tumor cells. In addition, anti-CD99 monoclonal antibodies exhibit antitumor activities in xenografts in the absence of immune effector cells or complement proteins. Overall, these data establish CD99 as a new opportunity to treat patients with high expression of CD99, particularly those that are resistant to canonical apoptosis-inducing agents.

Meningioma presenting as temporal region swelling: Diagnosis by cytopathology and immunohistochemical confirmation on cell block preparation

Meningiomas are common intracranial neoplasms. Meningomas are rarely subjected to fine-needle aspiration (FNA) studies. However, intraoperative squash preparations are commonly done. FNA of meningiomas are usually performed incidentally for cases with a clinical suspicion of some other disease such as metastatic carcinoma. We are reporting two cases, which were referred to our center with a diagnosis of metastatic carcinoma on FNA from swelling of the temporal region. We are discussing the characteristic cytomorphological features, which help in diagnosing meningiomas, the common cytological differentials, and the utility of immunohistochemistry (IHC) on cell block preparations in confirming the diagnosis, especially when there is a clinical differential diagnosis.

Malignant progression to anaplastic meningioma: Neuropathology, molecular pathology, and experimental models

Meningioma is a common adult intracranial tumor, and while several cases are considered benign, a subset is malignant with biologically aggressive behavior and is refractory to current treatment strategies of combined surgery and radiotherapy. Anaplastic meningiomas are quite aggressive and correspond to a World Health Organization (WHO) Grade III tumor. This highly aggressive phenotype mandates the need for more efficacious therapies. Designing rational therapies for treatment will have its foundation in the biologic understanding of involved genes and molecular pathways in these types of tumors. Anaplastic meningiomas (WHO Grade III) can arise from malignant transformation of lower grade (WHO Grade I/II) tumors, however there is an incomplete understanding of specific genetic drivers of malignant transformation in these tumors. Here, the current understanding of anaplastic meningiomas is reviewed in the context of human neuropathologic specimens and small animal models.

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.

Primary ectopic atypical meningioma in the renal hilum: a case report

BACKGROUND

Primary ectopic atypical meningioma involving the renal hilum is rare. This is, to our knowledge, only the second case report of a primary retroperitoneal meningioma and the first case of an atypical subtype in this location.

CASE PRESENTATION

A 53-year-old Han Chinese man presented with a 2-year history of left-side flank pain. An oval-shaped retroperitoneal mass was found in the left renal hilum on computed tomography, which was resected en bloc along with the kidney via laparotomy. According to the World Health Organization criteria, the tumor was histopathologically classified as a meningioma (Grade II, atypical). Five years later, the tumor recurred at the primary site with a similar histopathology. The patient received palliative resection, followed by radiotherapy (4500 cGy in 25 fractions). No relapse was found at 6-month follow-up.

CONCLUSION

We describe the clinical, radiographic and histopathological features of an unusual case of aggressive ectopic meningioma in the renal hilum. The patient presented with a massive retroperitoneal tumor without primary cerebral or secondary metastatic lesions; the preoperative diagnosis was naturally confined to the common retroperitoneal malignancies. This case is of interest to oncologists, because of both its rare location and aggressiveness; it not only enriched the spectrum of primary ectopic meningioma, but also reminded us of potential recurrence of an atypical meningioma. This case raises the issue of the etiology of such a rare tumor that needs further investigation, and more importantly demands long-term follow-up result.

Rare primary central nervous system tumors

There are close to 70,000 new cases of primary central nervous system tumors diagnosed annually in the United States. Meningiomas, gliomas, nerve sheath tumors and pituitary tumors account for 85% of them. There is abundant literature on these commonly occurring tumors but data from the literature on infrequently encountered tumors such as atypical teratoid/rhabdoid tumor, choroid plexus carcinoma, ganglioglioma, hemangiopericytoma, and pleomorphic xanthoastrocytoma are limited. This review provides an overview of the clinicopathologic and therapeutic aspects of these rare primary central nervous system tumors.

Comparison of ADC values of intracranial hemangiopericytomas and angiomatous and anaplastic meningiomas

PURPOSE

This study aimed to determine whether the use of apparent diffusion coefficient (ADC) values can improve the diagnostic efficacy of magnetic resonance imaging (MRI) to differentiate hemangiopericytoma (HPC) from angiomatous and anaplastic meningioma.

MATERIALS AND METHODS

Preoperative diffusion-weighted imaging (DWI) studies of 38 patients with pathologically proven intracranial HPC (n = 12) and angiomatous (n = 13) or anaplastic meningioma (n = 13) were retrospectively reviewed. ADC values were measured in the tumor parenchyma and peritumoral edema, and used to obtain normalized ADC (NADC) ratios (ADC of tumor/ADC of normal white matter).

RESULTS

Mean ADC values were significantly different between HPC and anaplastic meningioma (1.17 ± 0.30 × 10(-3) mm(2)/s and 0.75 ± 0.11 × 10(-3) mm(2)/s, respectively). Mean NADC ratios were also significantly lower in the malignant cases (0.95 ± 0.13) compared with the benign HPCs (1.53 ± 0.39; P < 0.05). Mean ADC values and NADC ratios did not differ significantly between angiomatous meningioma and HPC (P > 0.05), whereas mean ADC values and NADC ratios were lower for anaplastic meningioma than for either angiomatous meningioma or HPC (P < 0.05). Mean ADC value in peritumoral edema in HPC (1.48 ± 0.11 × 10(-3) mm(2)/s) was lower than in either angiomatous (1.73 ± 0.28 × 10(-3) mm(2)/s) or anaplastic (1.72 ± 0.25 × 10(-3) mm(2)/s) meningioma (P < 0.05), and there was no significant difference between ADC values in anaplastic versus angiomatous meningioma (P > 0.05).

CONCLUSION

ADC values in tumor parenchyma and peritumoral edema can provide helpful information that is otherwise not available from conventional MRI to differentiate HPC from angiomatous and anaplastic meningioma.

Cytopathology of extracranial ectopic and metastatic meningiomas

INTRODUCTION

Extracranial meningiomas may infrequently be encountered as ectopic or metastatic tumors. Their rarity and unique cytomorphology often pose significant diagnostic dilemmas. The aim of this study was to report our experience with a series of ectopic and metastatic meningiomas, characterizing their cytomorphology with histological correlation.

MATERIALS AND METHODS

A retrospective analysis involving 13 patients with cytological preparations from extracranial meningiomas was performed. Cytology cases were correlated with available surgical resection specimens. Data regarding clinical findings, tumor information, cytomorphology, follow-up histological features and immunohistochemistry were recorded and analyzed.

RESULTS

There were 5 cases with metastases and 8 ectopic meningiomas. Metastases occurred in the scalp/skull, lung, paraspinal soft tissue and liver. Primary ectopic meningiomas were located in the paranasal sinuses and ear, orbit and neck. Cytomorphological features characteristic of meningiomas were identified in the majority of samples including tightly cohesive clusters of spindled cells, whorls, intranuclear inclusions, nuclear grooves and psammomatous calcification. Unusual cytomorphological features identified in only a few cases included epithelioid cell predominance, abundant inflammatory cells, small-cell change, papillary structures and pseudoacinar growth. Metastatic tumors exhibited more nuclear atypia and occasionally mitoses or necrosis. Meningiomas were shown to be immunoreactive for epithelial membrane antigen, pancytokeratin and vimentin.

CONCLUSION

Although rare, extracranial meningiomas can be encountered in cytologic specimens and should be included in the differential diagnosis when characteristic morphological features of meningiomas are seen. Cytopathologists should be aware that these lesions could be mistaken for other tumors, especially when confounded by atypia and unusual cytomorphological features.

Meningeal hemangiopericytoma and solitary fibrous tumors carry the NAB2-STAT6 fusion and can be diagnosed by nuclear expression of STAT6 protein

Non-central nervous system hemangiopericytoma (HPC) and solitary fibrous tumor (SFT) are considered by pathologists as two variants of a single tumor entity now subsumed under the entity SFT. Recent detection of frequent NAB2-STAT6 fusions in both, HPC and SFT, provided additional support for this view. On the other hand, current neuropathological practice still distinguishes between HPC and SFT. The present study set out to identify genes involved in the formation of meningeal HPC. We performed exome sequencing and detected the NAB2-STAT6 fusion in DNA of 8/10 meningeal HPC thereby providing evidence of close relationship of these tumors with peripheral SFT. Due to the considerable effort required for exome sequencing, we sought to explore surrogate markers for the NAB2-STAT6 fusion protein. We adopted the Duolink proximity ligation assay and demonstrated the presence of NAB2-STAT6 fusion protein in 17/17 HPC and the absence in 15/15 meningiomas. More practical, presence of the NAB2-STAT6 fusion protein resulted in a strong nuclear signal in STAT6 immunohistochemistry. The nuclear reallocation of STAT6 was detected in 35/37 meningeal HPC and 25/25 meningeal SFT but not in 87 meningiomas representing the most important differential diagnosis. Tissues not harboring the NAB2-STAT6 fusion protein presented with nuclear expression of NAB2 and cytoplasmic expression of STAT6 proteins. In conclusion, we provide strong evidence for meningeal HPC and SFT to constitute variants of a single entity which is defined by NAB2-STAT6 fusion. In addition, we demonstrate that this fusion can be rapidly detected by STAT6 immunohistochemistry which shows a consistent nuclear reallocation. This immunohistochemical assay may prove valuable for the differentiation of HPC and SFT from other mesenchymal neoplasms.

A meningioma with peripheral rim enhancement on MRI

Meningiomas are common, typically benign intracranial neoplasms with well-demarcated borders.Meningiomas with indistinct boundaries have been reported.These can invade surrounding structures, and present surgical and diagnostic challenges. We present the case of an unusual meningioma in a 53-year-old male in which preoperative magnetic resonance imaging (MRI) revealed an irregular lesion with clear boundaries and peripheral rim enhancement. Intraoperatively, however, no cleavage plane was apparent. Histological examination showed an increase of fibroconnective tissue with proliferation of dilated vessels in the periphery of the tumor concordant with the rim.Immunohistochemical staining of the tumor was positive for EMA and CD34, but negative for CEA, Ki67, and GFAP. Immunohistochemical staining of proliferating vessels in the periphery of the tumor was positive for CD34. A so-called ‘capsule’ structure was suggested according to MRI findings and pathological examination.The tumor was diagnosed as a mixed type meningioma,WHO grade I.

Slug, twist, and E-cadherin as immunohistochemical biomarkers in meningeal tumors

The overexpression of Twist and Slug and subsequent down-regulation of E-cadherin facilitate the acquirement of invasive growth properties in cancer cells. It is unclear which of these molecules are expressed in mesenchymal tumors in the central nervous system. Here, we investigated 10 cases each of hemangiopericytoma, solitary fibrous tumor, meningothelial, fibrous, angiomatous, and atypical meningiomas, and 5 cases of anaplastic meningioma for Slug, Twist, E-cadherin, and N-cadherin immunoexpression. Nuclear Slug expression was observed in 9/10 (90%) hemangiopericytomas and 5/10 (50%) solitary fibrous tumors, but not in any meningiomas, except for 1 case. Similarly, nuclear Twist expression was more extensive in hemangiopericytomas and solitary fibrous tumors than meningiomas. In contrast to Slug and Twist, the positive expression of E-cadherin was observed in 39/45 (87%) meningiomas, but not in any hemangiopericytomas or solitary fibrous tumors (P<0.0001). The fraction of tumor cells expressing E-cadherin in meningeal tumors was negatively correlated to those of Twist (P = 0.004) and Slug (P<0.0001). The overexpression of Slug and Twist with down-regulation of E-cadherin was characteristic findings in hemangiopericytomas and solitary fibrous tumors, but not in meningiomas. The immunohistochemical profiles of the two tumor groups may be useful as diagnostic markers in cases that present a differential diagnosis challenge.

Haemangiopericytoma with no dural attachment

The authors describe a case of a gentleman in his 40s who presented with a space-occupying lesion in the right precentral gyrus which showed no dural attachment and was well circumscribed, both on imaging and at surgery. This lesion was histologically challenging to diagnose but favoured to be a haemangiopericytoma. The lack of dural attachment is unusual for this tumour type but is typically associated with metastases to the brain, and less commonly a solid primary central nervous system tumour. The authors propose that haemangiopericytoma should be regularly considered as a differential diagnosis of cerebral metastases so that inadequate preoperative anticipation and planning is not encountered.

Iodothyronine deiodinases and cancer

Thyroid hormones (TH) regulate key cellular processes, including proliferation, differentiation, and apoptosis in virtually all human cells. Disturbances in TH pathway and the resulting deregulation of these processes have been linked with neoplasia. The concentrations of TH in peripheral tissues are regulated via the activity of iodothyronine deiodinases. There are 3 types of these enzymes: type 1 and type 2 deiodinases are involved in TH activation while type 3 deiodinase inactivates TH. Expression and activity of iodothyronine deiodinases are disturbed in different types of neoplasia. According to the limited number of studies in cancer cell lines and mouse models changes in intratumoral and extratumoral T3 concentrations may influence proliferation rate and metastatic progression. Recent findings showing that increased expression of type 3 deiodinases may lead to enhanced tumoral proliferation support the idea that deiodinating enzymes have the potential to influence cancer progression. This review summarizes the observations of impaired expression and activity in different cancer types, published to date, and the mechanisms behind these alterations, including impaired regulation via TH receptors, transforming growth factor-β, and Sonic-hedgehog pathway. Possible roles of deiodinases as cancer markers and potential modulators of tumor progression are also discussed.

Intracranial hemangiopericytoma: Case study with cytogenetics and genome wide SNP-A analysis

The tumor entity of hemangiopericytoma is not universally recognized as a nosological entity by pathologists, and there is a trend toward reassigning it to other categories gradually. However, hemangiopericytomas occurring in the nervous system are included in the new WHO classification of brain tumors, and are distinguished from both meningioma and fibrous tumors. Since there are few genetic studies, we performed a comprehensive cytogenetic analysis of an infratentorial hemangiopericytoma in a 55-year-old female. It was originally classified as a grade II tumor but recurred as a grade III tumor with a proliferation index of 20%. Using trypsin-Giemsa staining (GTG-banding) and multicolor fluorescence in situ hybridization (M-FISH), we could confirm the loss of chromosomal material 10q, which has been previously described in hemangiopericytoma, and we identified de novo chromosomal aberrations on chromosome 8. Applying genome-wide high-density single nucleotide polymorphism array (SNP-A) analysis, we detected segments with loss or gain, as well as clonal deletions or regions suggestive of segmental uniparental disomy. These findings, together with the results of conventional histological and immunohistochemical characterization, provide additional evidence for the nosological separation of hemangiopericytoma in the central nervous system as a biologically different entity.

Anaplastic Meningioma Arising From a Radiologically Diagnosed Arachnoid Cyst

OBJECTIVE AND IMPORTANCE

We report the first example of an anaplastic meningioma arising from an intracranial arachnoid cyst and discuss the diagnostic challenges of this case, including the useful role of genetic markers.

CLINICAL PRESENTATION

A 72-year-old man presented with transient episodes of expressive dysphasia and focal motor seizures, superimposed on a 6-month history of worsening headaches and dizziness. His past history was significant for a previously drained left-sided chronic subdural hematoma and a radiologically diagnosed left middle fossa arachnoid cyst. Magnetic resonance imaging on admission showed variable wall thickening of the arachnoid cyst with mild mass effect on the left frontotemporal lobes.

INTERVENTION

The patient underwent decompression of the arachnoid cyst and biopsy of the cyst wall. Histologic and immunohistochemical studies of the thickened portion initially suggested a metastatic carcinosarcoma, but fluorescence in situ hybridization (FISH) studies confirmed the diagnosis of anaplastic meningioma based on characteristic chromosomal deletions. The patient returned 2 months later with progressive disease, leading to his death 6 weeks later despite repeat surgery for tumor debulking.

CONCLUSION

Malignant transformation of meningothelial elements in arachnoid cysts is an exceptionally rare complication that poses considerable diagnostic challenges. Genetic markers may be particularly helpful in such cases.

Metastatic recurrence of an intracranial hemangiopericytoma 8 years after treatment: report of a case with emphasis on the role of PET/CT in follow-up

Intracranial meningeal hemangiopericytomas are rare tumors that can mimic meningioma on imaging and on histopathology. However, these tumors are more aggressive with a tendency for local and metastatic recurrence, sometimes after a prolonged symptom-free interval. We report an unusual metastatic recurrence of an intracranial hemangiopericytoma, 8 years after surgery for the primary tumor and discuss the role of positron emission tomography/computed tomography in the follow-up of these patients.

Immunohistochemical Detection of CD34, E-cadherin, Claudin-1, Glucose Transporter 1, Laminin, and Protein Gene Product 9.5 in 28 Canine and 8 Feline Meningiomas

The variation in histologic pattern of meningiomas can make their diagnosis challenging. The immunohistochemical profile of 28 canine and 8 feline meningiomas was examined. Tumor types included anaplastic (6 dogs), angiomatoid (1 cat), fibroblastic (3 dogs, 1 cat), meningothelial (1 dog), microcystic (2 dogs), myxoid (3 dogs), psammomatous (4 cats), and transitional (13 dogs, 2 cats). The authors compared the expression of novel markers (CD34, E-cadherin, claudin-1, glucose transporter 1 [GLUT-1], laminin, and protein gene product [PGP] 9.5) with published markers (cytokeratins, glial fibrillary acidic protein [GFAP], progesterone receptor, S100, and vimentin). Neoplastic cells were immunohistochemically positive for vimentin in 100% of the meningiomas; CD34, 94%; GLUT-1, 86%; E-cadherin, 81%; S100, 75%; laminin, 72%; claudin-1, 60%; PGP 9.5, 55%; progesterone receptor, 44%; pancytokeratins, 39%; cytokeratins 8/18, 17%, and GFAP in 9%. Ki67 index did not correlate well with mitotic index. Based on these results and those in the human literature, immunohistochemistry for vimentin, CD34, and E-cadherin is proposed to support a diagnosis of meningioma. Immunohistochemistry for claudin-1, albeit of only moderate to low sensitivity in canine and feline meningiomas, may help to distinguish meningioma from some mesenchymal neoplasms involving the brain and associated structures, such as schwannomas, which in humans express claudin-1 poorly or not at all. Further studies with CD34, E-cadherin, and claudin-1 in canine and feline tumors that may mimic meningiomas are needed to determine the adequacy of this approach.

Minute myopericytoma of the neck: a case report with literature review and differential diagnosis

Reports of cutaneous myopericytoma (MPC) are very rare. The author herein reports a case of minute MPC of the neck. A 56-year-old woman noticed a painful small tumor in the neck, and consulted to our hospital. Dermatologists's diagnosis is a hyperplastic lymph node. Excision of the tumor was performed. Grossly, the tumor was a sold white tumor measuring 3 × 3 × 3 mm. Microscopically, it consisted of many vascular channels and perivascular cell proliferation encased by a fibrous capsule. The vascular proliferation showed a hemangiopericytoma (HPC)-like pattern such as staghorn-like vessels. Fibrosis was not present. The HPC-like cells had vesicular nuclei and polygonal cytoplasm. No atypia is recognized. The HPC-like cells focally showed vague nodular proliferation around the vessels. Immunohistocheically, the tumor cells were negative for cytokeratin, and positive for vimentin. The vasculatures were positive for factor VIII-related antigen, CD34, and CD31. The HPC-like tumor cells were positive for α-smooth muscle actin and h-caldesmon, but negative for desmin, S100 protein, melanosome, bcl-2, CD99, and KIT. The Ki-67 labeling was 8% and p53 was negative. The pathologic diagnosis was MPC of the neck skin. The patient is now alive without recurrence 4 years after the excision. A review of the literature revealed 73 cases of MPC from 6 papers. MPC is male predominance, and the patients ages ranges from 13 to 87 years with the median of 47 years. The most common location was lower extremities followed in order by upper extremities, head and neck, and trunk. One MPC occurred within the vasculature, and 3 cases of MPC developed in the scar or trauma lesions. The prognosis after excision is good, but a very minority showed local recurrence. A differential diagnosis was also made.

Liver recurrence of a subcutaneous temporal hemangiopericytoma: the index case

INTRODUCTION

Hemangiopericytoma is an uncommon soft tissue vascular neoplasm. Intraperitoneal hemangiopericytomas such as primary or secondary liver location have been exceptionally described. Its natural history is mostly benign, but recurrences may occur and determining if these late-discovered tumors are distant metastases or synchronous slow and silent-growing locations is sometimes challenging. The histopathological diagnosis and definition of hemangiopericytoma is based on its distinction with solitary fibrous tumors. Liver resection to treat liver hemangiopericytoma seems to be supported by various published experiences.

CASE PRESENTATION

We herein report the first case of liver metastases from a subcutaneous temporal hemangiopericytoma. The patient was treated by a liver resection. CD34 Immunostaining was negative, but strong expression of Bcl2 and CD99 was found in the neoplastic cells. After 1 year of follow-up, the patient is alive without recurrence.

CONCLUSION

To date, published data, including the case herein reported, support the need for a prolonged follow-up and the role of liver resection to treat liver metastases of hemangiopericytomas. Complete resection of all gross disease appears to be the most significant prognostic factor.

Sequential salvage chemotherapy for recurrent intracranial hemangiopericytoma

OBJECTIVE

Hemangiopericytoma (HPC) is an uncommon primary brain tumor with an almost invariable tendency to recur and metastasize. We undertook a retrospectively collected case series of recurrent intracranial HPCs treated with salvage chemotherapy with the primary objective of evaluating progression-free survival.

METHODS

Fifteen patients, ages 26 to 62 years, with recurrent HPC and who were previously treated with surgery and involved-field radiotherapy were studied. Eight (53%) of these patients had undergone re-resection before study entry. Ten patients (67%) were treated with stereotactic radiotherapy. Chemotherapy was administered to 5 patients at first relapse, 8 at second relapse, and 2 at third relapse (none of these patients were candidates for reoperation or stereotactic radiotherapy). Eight patients developed disseminated disease, all with multifocal intracranial disease (5 with cerebrospinal fluid dissemination, 4 with extraneural metastases). All patients were initially treated with cyclophosphamide, doxorubicin, and vincristine (CAV). After disease progression despite the administration of CAV in clinically appropriate patients, alpha-interferon (alpha-IFN) (9 patients) was administered. Five patients were treated with ifosfamide, cisplatin, and etoposide after they failed to respond to alpha-IFN. Neurological and neuroradiographic evaluations were performed every 8 weeks.

RESULTS

All patients were evaluable. A median of 4 cycles of CAV; 8 cycles of alpha-IFN; and 2 cycles of ifosfamide, cisplatin, and etoposide were administered. Chemotherapy-related toxicity included alopecia (100%), anemia (40%), thrombocytopenia (27%), and neutropenia (40%). Best response included 6 patients (40%) with a neuroradiographic partial response (2 with CAV, 4 with alpha-IFN), 14 (93%) had stable disease (9 with CAV, 5 with alpha-IFN), and 9 (60%) had progressive disease (4 with CAV, 5 with ifosfamide, cisplatin, and etoposide). The median overall survival was 14 months (range, 2-24 mo).

CONCLUSION

Salvage chemotherapy demonstrated modest efficacy with acceptable toxicity in this cohort of adult patients with recurrent surgery- and radiotherapy-refractory intracranial HPC.

Primary intracranial dural-based synovial sarcoma with an unusual SYT fluorescence in situ hybridization pattern

The authors present the case of an elderly man with a primary dural-based intracranial synovial sarcoma. Histological and immunohistochemical profiles of the lesion were diagnostic for a synovial sarcoma, and molecular studies using fluorescence in situ hybridization were compatible with a synovial sarcoma. A wide array of spindle cell neoplasms has been described as originating in the dura. To the authors' knowledge, however, this is only the second primary durabased intracranial synovial sarcoma ever reported, emphasizing the importance of a broad differential diagnosis when encountering spindle cell lesions of the meninges.

The 2007 WHO classification of tumors of the nervous system: controversies in surgical neuropathology

Controversy surrounds the recent 2007 WHO Classification of Tumours of the Nervous System. A number of nosologic issues remain to be resolved, some a reflection of conceptual disagreement, others the result of inadequate data to permit their definitive resolution. Among these and discussed herein are (i) the nosologic place of highly anaplastic oligoastrocytic tumors, (ii) the forms and significance of microvascular changes in high-grade gliomas, (iii) the makeup of the glioneuronal tumors category, (iv) the subclassification of pineal parenchymal tumors of intermediate type, and (v) the classification of principle forms of mesenchymal neoplasms, specifically hemangiopericytoma and solitary fibrous tumor. These issues and others are the substance of this and an upcoming companion article.

Review of meningioma histopathology

✓The histological appearance of a meningioma is an important predictor of tumor behavior and is frequently a factor in decisions concerning therapy. The relationship between histological features and prognosis is formalized in grading schemes such as those published by the World Health Organization (WHO), most recently in 2007. Although the latest edition is an improvement over previous grading schemes, the WHO scheme still fails to fully address a variety of important issues regarding the relationship between meningioma histological characteristics and behavior. In particular, routine histological examination fails to identify the subset of Grade I tumors that behave aggressively. Because of this, many additional prognostic markers that require immunohistochemical, cytogenetic, or molecular techniques to evaluate are under investigation. Only one, immunohistochemistry for the proliferation marker, Ki 67 (MIB-1), is used routinely and it has only limited utility. It is hoped that an understanding of the genetic changes that underlie tumor progression will improve healthcare professionals' ability to predict the behavior of meningiomas.

Primary Ewing sarcoma of the brain: a case report and literature review

Ewing sarcoma, along with peripheral primitive neuroectodermal tumor, belongs to a tumor family that shares clinicopathologic and molecular genetic features, including the characteristic chromosomal translocation that results in the fusion of the EWS gene on 22q12 to either the FLI1 gene on 11q24 or other Ets family transcription factor gene, such as the ERG gene on 21q22. In contrast, such translocations are not found in central primitive neuroectodermal tumors (cPNETs), such as medulloblastoma and supratentorial PNET. Ewing sarcoma has only rarely been noted to primarily involve the central nervous system-extraosseous Ewing sarcoma (CNS-EES). We report a case of a 7-year-old girl with an anterior cranial fossa mass. Pathology showed a primitive small blue cell tumor with focal Homer Wright rosette formation. The positive membranous immunostaining for CD99 and the EWS-FLI1 fusion demonstrated by fluorescence in situ hybridization studies confirmed the diagnosis of CNS-EES. Although CNS-EES may look identical to cPNETs, these tumors differ in histogenesis, molecular characteristics, and clinical behavior. Demonstration of characteristic translocations by molecular studies differentiates CNS-EES from cPNET and help clinicians make informed decisions regarding therapy.

High throughput screening of meningioma biomarkers using a tissue microarray

Meningiomas are histologically and clinically diverse CNS neoplasms with few available immunohistochemical markers of differentiation and progression. Therefore, we investigated a panel of potentially useful meningioma-associated biomarkers using high throughput tissue microarray immunohistochemistry (TMA-IHC) with a TMA that includes 9 hemangiopericytomas (HPCs) and 41 meningiomas spanning all grades, as well as two subsets of atypical meningiomas, stratified according to clinical behavior. Antibodies utilized were progesterone receptor (PR), epithelial membrane antigen (EMA), cathepsin D, E-cadherin, platelet derived growth factor (PDGF) receptor beta, PDGF BB ligand, survivin, epithelial growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF). In most cases, frequencies of tumor positivity were similar to those previously reported using whole section IHC. EMA, E-cadherin, and PDGFR-beta staining patterns distinguished the anaplastic meningiomas from the HPCs (P < 0.001, P = 0.02, P = 0.015, respectively). As in prior studies, PR and cathepsin D expression were inversely proportional to tumor grade. However, PR and EGFR were also differentially expressed between symptomatic, surgically resected benign meningiomas and incidental meningiomas found at autopsy. We conclude that (1) TMA-IHC is an accurate and efficient way to rapidly assess biomarkers in meningeal tumors, (2) EMA, E-cadherin, and PDGFR-beta are useful in distinguishing anaplastic meningiomas from HPCs, and (3) the expression patterns for incidental meningiomas differ slightly from their surgically resected symptomatic counterparts.

Molecular diagnostics in central nervous system tumors

Central nervous system (CNS) neoplasms can be diagnostically challenging, due to remarkably wide ranges in histologic appearance, biologic behavior, and therapeutic approach. Nevertheless, accurate diagnosis is the critical first step in providing optimal patient care. As with other oncology-based specialties, there is a rapidly expanding interest and enthusiasm for identifying and utilizing new biomarkers to enhance the day-to-day practice of surgical neuropathology. In this regard, the field is primed by recent advances in basic research, elucidating the molecular mechanisms of tumorigenesis and progression in the most common adult and pediatric brain tumors. Thus far, few have made the transition into routine clinical practice, the most notable example being 1p and 19q testing in oligodendroglial tumors. However, the field is rapidly evolving and many other biomarkers are likely to emerge as useful ancillary diagnostic, prognostic, or therapeutic aids. The goal of this article is to highlight the most common genetic alterations currently implicated in CNS tumors, focusing most on those that are either already in common use in ancillary molecular diagnostics testing or are likely to become so in the near future.