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Background: Malignant meningiomas are rare neoplasms of the central nervous system that occur de novo or rarely as a result of transformation. They have a higher rate of recurrence and metastasis accompanied by a significantly shorter survivorship compared with benign variants. Meningioma cancer stem cells (CSCs) have been previously shown to be associated with resistance and aggressiveness. However, the role they play in meningioma progression is still being investigated., Case Description: We report a 29-year-old man who underwent a resection of a grade I meningioma in 2011. The patient had multiple local recurrences of the tumor that showed an aggressive change in behavior and transformation to grade III meningioma, and developed extracranial metastasis to the cervical spine. He underwent multiple operations and received radiotherapy. Analysis of the tissues indicated the presence of CSC markers before metastasis, and showed increased expressions of associated markers in the metastasized tissue. In addition, similar to the patient's profile, the pharmacological testing of a primary cell line retrieved from the metastasized tissues showed a high level of drug tolerance and a diminished ability to initiate apoptosis., Conclusions: Malignant progression of grade I meningioma can occur, and its eventuality may be anticipated by detecting CSCs. We performed a comprehensive literature review of relevant cases and discussed the clinical, diagnostic, and management characteristics of the reported cases., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose Minute pulmonary meningothelial-like nodules are incidentally discovered in lung specimens. We analyzed the clinicopathologic features of 14 cases identified in surgically resected lungs. Methods Among patients who underwent lung resection in our hospital from October 2007 to March 2016, 14 were found to have minute pulmonary meningothelial-like nodules. The clinical parameters, radiologic findings, and pathologic features of these patients were retrospectively reviewed using the medical records. Results The patients included 4 men and 10 women, with a mean age of 69 years (range 53-82 years). The coexisting main disease was adenocarcinoma in 8 patients, squamous cell carcinoma in 1, atypical adenomatous hyperplasia in 1, and metastatic pulmonary tumor in 3. In one patient, the minute pulmonary meningothelial-like nodules presented as multiple lung nodules on chest computed tomography. The median size of the nodules was 1.4 mm (range 0.3-6.0 mm). Similar to meningioma, one case had immunoreactivity to progesterone receptor and epithelial membrane antigen, although the minute pulmonary meningothelial-like nodules were not associated with a meningioma. Conclusions The relationship between minute pulmonary meningothelial-like nodules and meningioma should be investigated. If minute pulmonary meningothelial-like nodules are found on preoperative computed tomography, thoracoscopic lung biopsy is helpful for differential diagnosis.

A lymphoplasmacyte-rich meningioma (LPRM) is an extremely rare variant of meningioma. Here, we report a case of atypical LPRM with increased mitosis in a 55-year-old man. Preoperative magnetic resonance imaging suggested meningioma with brain invasion in the left tentorium cerebelli. Histological examination revealed sclerotic fibrosis and dense lymphoplasmacytic infiltration; based on these findings, the differential diagnosis included LPRM and fibroinflammatory lesions of the dura, such as idiopathic hypertrophic pachymeningitis (IHP), IgG4-related disease (IgG4-RD), and Rosai-Dorfman disease. Epithelial membrane antigen (EMA) immunostaining highlighted sheets of meningothelial cells, which strongly supported the diagnosis of meningioma. Although brain invasion was suspected in radiologic image, no histologic evidence of brain invasion was found. However, the mitoses were observed to be 8/10 high power fields, along with increased Ki-67 labeling index with focal spontaneous necrosis, and the final pathologic diagnosis was atypical LPRM. IgG4-RD was ruled out, because IgG4 counts and the IgG4:IgG ratio of plasma cells did not meet the diagnostic criteria for IgG4-RD. To date, only one case of LPRM with brain invasion has been reported as atypical LPRM. This case is therefore the second case of atypical LPRM with increased mitosis that histologically mimicked IHP.

Primary extradural meningiomas of the skull comprise 1% of all meningiomas, and lytic skull meningiomas are still rarer and are said to be more aggressive. We present a case of 38-year-old male with an extradural tumor which on histopathological examination showed features of inflammatory atypical meningioma (WHO Grade II). The intense inflammatory nature of osteolytic primary intraosseous meningioma has not been reported before. This entity deserves special mention because of the need for adjuvant therapy and proper follow-up.

We report on a 51-year-old woman who presented with a cervical spinal cord tumor clinically suspected to be a metastasis. Histological examination revealed an anaplastic meningioma containing epithelial nests arranged in a gland-like pattern suggestive of adenocarcinoma. This component strongly expressed cytokeratins whereas the meningothelial component was vimentin--epithelial membrane antigen--and progesterone receptor-immunoreactive, suggesting either anaplastic meningioma with adenocarcinoma-like metaplasia, or adenocarcinoma metastasis in a meningioma, but the search for a primitive neoplasia including thoracic-abdominal-pelvic computed tomography and mammography was negative. Anaplastic meningiomas with adenocarcinoma-like metaplasia are uncommon lesions, 4 cases having been reported in the literature so far. Their immunohistochemical and chromosomal characteristics are similar to those observed in secretory meningiomas. When available, fluorescence in situ hybridization detects the same chromosomal alterations in the two components, confirming a common clonal origin. This observation demonstrates the necessity to perform the correct diagnosis of malignant meningioma with adenocarcinomatous metaplasia, whose prognosis and treatment radically differ from those of metastatic adenocarcinoma located in a meningioma., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Meningiomas are tumors of the central nervous system that rarely present as extracranial soft tissue masses. Meningioma of the skin is referred to as cutaneous meningioma. Cutaneous meningioma of the scalp is extremely rare and may cause diagnostic challenges. A 70-year-old female patient presented with a painless mass on her scalp. A punch biopsy was performed; histological examination of the specimen revealed an infiltration of spindle-shaped and epithelioid atypical cells arranged in whorls. Immunohistochemistry was positive for vimentin and epithelial membrane antigen. On magnetic resonance imaging, a large intracranial mass eroding through the skull was observed. A diagnosis of intracranial anaplastic meningioma was established and excision was performed in the Department of Neurosurgery. It is important to consider intracranial tumors in the differential diagnosis of nodules on scalp.

Although surgical resection of benign human meningiomas is the primary goal, in case of relapse or when they are not fully resectable, other strategies including chemotherapeutical treatment would be appropriate. The initial evaluation of chemotherapeutical agents requires an appropriate tumor model, where the natural characteristics of the original benign tumor is reflected. We here tested, whether primary cell cultures of benign human meningiomas would reliably grow after intracranial transplantation into mice, and whether they would show histomorphological and immunohistochemical characteristics of the original human tumor. Cells of 11 benign human meningiomas were transplanted into the prefrontal cortex of nude mice. After 3 months, the mice were sacrificed and their brains were histologically processed for morphological characterization and measurement of tumor volume. Additionally, the proliferation index (PI), the microvessel density, and epithelial membrane antigen (EMA) were compared between human meningiomas and tumors grown in mice by using immunohistochemical methods. Further, cyclooxygenase-2 (COX-2) expression, a possible target for pharmacological manipulation, was examined. The results showed in almost all mice (93%) a tumor formation with meningothelial histomorphology comparable to the original human tumors. The PI, vascular density and COX-2 expression were similar between human and mice meningiomas, but EMA expression was reduced in mice (P<0.01). In conclusion an implantation of benign human meningioma primary cell cultures in mice reliably results in tumor formation with morphological and immunohistological features comparable to the original human tumor. This model may therefore be suitable to test novel therapeutic agents., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The spatial and temporal pattern of appearance of nestin, epithelial membrane antigen (EMA) and mesothelin proteins was immunohistochemically determined in the cells of normal developing and adult human meninges and meningiomas. Human meninges developed as two mesenchymal condensations in the head region. The simple squamous epithelium on the surface of leptomeninges developed during mesenchymal to epithelial transformation. Nestin appeared for the first time in week 7, EMA in week 8, while mesothelin appeared in week 22 of development. In the late fetal period and after birth, nestin expression decreased, whereas expression of EMA and mesothelin increased. EMA appeared in all surface epithelial cells and nodules, while mesothelin was found only in some of them. In adult meninges, all three proteins were predominantly localized in the surface epithelium and meningeal nodules. In meningothelial meningiomas (WHO grade I), EMA was detected in all tumor cells except in the endothelial cells, mesothelin characterized nests of tumor cells, while nestin was found predominantly in the walls of blood vessels. The distribution pattern of those proteins in normal meningeal and tumor cells indicates that nestin might characterize immature cells, while EMA and mesothelin appeared in maturing epithelial cells. Neoplastic transformation of these specific cell lineages contributes to the cell population in meningiomas., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

The authors expose the clinical, radiological and histological presentation of three cases of solitary fibrous tumors of the meninges, initially thought to be meningiomas. Actually, these three cases show typical anatomoclinical features. The authors also mention the differential diagnosis, and recall the essential contribution of immunohistochemistry., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Aims: Clear cell meningioma (CCM) is a rare variant of meningioma, which is important to distinguish because of its aggressive behaviour. Sixty-eight cases have been previously described in the literature. In this retrospective study, we report seven cases of CCM operated in our institution between 1994 and 2008., Methods: Seven CCM cases were retrieved from the files of our pathology department. Clinical and radiological data were reviewed. A standard histological study was realized and immunohistochemistry was performed with epithelial membrane antigen (EMA), cytokeratin KL1, progesterone receptors, Ki-67 (MIB-1), S100 protein., Results: Patients' age ranged from 2 to 70 years (median age: 36 years), with a female predominance (5/7 patients). Three patients belonged to the same family, probably affected by neurofibromatosis type 2. CCM occurred in various locations: medullary region (two), sphenoid wing (two), ponto-cerebellar angle (two), tentorium (one). The tumour could be fully resected in three cases. Follow-up ranged from 3 months to 15 years: recurrence occurred in four patients, three of whom eventually died from the disease., Discussion: In our series, the frequency of CCM (0,6% of all meningiomas operated on in our institution) and its histological aspects are almost identical to those observed of the literature. We discuss the predictive value of proliferation index (MIB-1) and the role of patient status and quality of surgical resection in the evolution., Conclusion: Our study supports the fact that MCC course is less favourable than meningioma WHO grade I, even in the absence of anaplastic area, high mitotic activity, or necrosis. In this series, MIB-1 index was of no interest identifying patients with or without recurrence., (Copyright 2010 Elsevier Masson SAS. All rights reserved.)

Meningioma is derived from arachnoid cells covering the surface of the brain and spinal cord, and it has characteristics shared by mesothelioma arising from the pleura and peritoneum in that it takes an epithelioid appearance despite its mesenchymal origin. We examined the immunohistochemical expression of podoplanin and calretinin, both of which are well-known markers of mesothelioma, in 24 surgical cases of meningioma of various types. In most cases, a linear immunoreactivity for podoplanin was found along the cell surface of most neoplastic cells. An intracytoplasmic, finely granular, or diffuse immunoreactivity was also noted in some cells. These findings corresponded well to immunoreactivity for epithelial membrane antigen (EMA), but immunoreactivity for podoplanin was more crisp or sharply delineated and clear compared with that for EMA. These findings indicate that podoplanin can be used as an immunohistochemical marker that is equivalent to EMA in the differential diagnosis of meningioma. However, most meningiomas did not contain calretinin-immunoreactive cells, a finding that differs from the diffuse immunoreactivity seen in mesothelioma.

Chordoid meningioma, World Health Organization grade II, is an uncommon variant of meningioma with a propensity for aggressive behavior and increased likelihood of recurrence. As such, recognition of this entity is important in cases that show similar morphologic overlap with other chondroid/myxoid neoplasms that can arise within or near the central nervous system. A formal comparison of the immunohistochemical features of chordoid meningioma versus tumors with significant histologic overlap has not been previously reported. In this study, immunohistochemical staining was performed with antibodies against D2-40, S100, pankeratin, epithelial membrane antigen (EMA), brachyury, and glial fibrillary acidic protein (GFAP) in 4 cases of chordoid glioma, 6 skeletal myxoid chondrosarcomas, 10 chordoid meningiomas, 16 extraskeletal myxoid chondrosarcoma, 18 chordomas, 22 low-grade chondrosarcomas, and 27 enchondromas. Staining extent and intensity were evaluated semiquantitatively and mean values for each parameter were calculated. Immunostaining with D2-40 showed positivity in 100% of skeletal myxoid chondrosarcomas, 96% of enchondromas, 95% of low-grade chondrosarcomas, 80% of chordoid meningiomas, and 75% of chordoid gliomas. Staining with S100 demonstrated diffuse, strong positivity in all (100%) chordoid gliomas, skeletal myxoid chondrosarcomas, low-grade chondrosarcomas, and enchondromas, 94% of chordomas, and 81% of extraskeletal myxoid chondrosarcomas, with focal, moderate staining in 40% of chordoid meningiomas. Pankeratin highlighted 100% of chordoid gliomas and chordomas, 38% of extraskeletal myxoid chondrosarcomas, and 20% of chordoid meningiomas. EMA staining was positive in 100% of chordoid gliomas, 94% of chordomas, 90% of chordoid meningiomas, and 25% of extraskeletal myxoid chondrosarcomas. Brachyury was positive only in the chordomas (100%), whereas GFAP was positive only in the chordoid gliomas (100%). EMA was the most effective antibody for differentiating chordoid meningioma from skeletal myxoid chondrosarcoma, low-grade chondrosarcoma, and enchondroma, whereas D2-40 was the most effective antibody for differentiating chordoid meningioma from extraskeletal myxoid chondrosarcoma and chordoma. Our findings demonstrate that in conjunction with clinical and radiographic findings, immunohistochemical evaluation with a panel of D2-40, EMA, brachyury, and GFAP is most useful in distinguishing chordoid meningioma from chordoid glioma, skeletal myxoid chondrosarcoma, extraskeletal myxoid chondrosarcoma, chordoma, low-grade chondrosarcoma, and enchondroma. A lack of strong, diffuse S100 reactivity may also be useful in excluding chordoid meningioma. Among the neoplasms evaluated, brachyury and GFAP proved to be both sensitive and specific markers for chordoma and chordoid glioma, respectively. Of note, this study is the first to characterize the D2-40 immunoprofile in extraskeletal myxoid chondrosarcoma, results that could be of utility in differential diagnostic assessment.

Chordoma originates from embryonic notochordal remnants in the midline along the spinal axis and is characterized by cords and lobules of neoplastic cells arranged within myxoid matrix. Because of histologic similarities with myxoid matrix and overlapping immunohistochemical profile, chondrosarcoma, myxopapillary ependymoma, and chordoid meningioma enter in the histologic differential diagnosis at this site. Therefore, the judicious use of a panel of selected immunostains is unquestionably helpful in diagnostically challenging cases. To find useful immunohistochemical markers for assisting in differential diagnosis between chordoma and other tumors with chordoid morphology, an immunohistochemical study using D2-40, epithelial membrane antigen (EMA), pan-cytokeratin (panCK), glial fibrillary acidic protein (GFAP), S-100 protein, galectin-3, neural cell adhesion molecule (NCAM), beta-catenin, E-cadherin, and carcinoembryonic antigen was performed on 14 chordomas, 7 chondrosarcomas, 9 myxopapillary ependymomas, and 4 chordoid meningiomas. Chordoma typically showed positive for EMA and panCK and negative for D2-40 and GFAP; whereas chondrosarcoma revealed positive for D2-40, and negative for EMA, panCK, and GFAP; myxopapillary ependymoma positive for GFAP and negative for EMA; and chordoid meningioma positive for EMA, and negative for panCK and GFAP. On the basis of our immunohistochemical study, a panel of D2-40, EMA, panCK, and GFAP allowed the correct recognition of all tumors examined. Other immunohistochemical markers including S-100 protein, galectin-3, NCAM, beta-catenin, E-cadherin, and carcinoembryonic antigen were of little value in differential diagnosis. In summary, the best immunohistochemical markers useful for the evaluation of tumors with chordoid morphology were D2-40, EMA, cytokeratin, and GFAP. D2-40 was a true chondroid marker to be useful for the differential diagnosis with chordoma.

Objective: Anaplastic meningioma is an uncommon neoplasm in childhood and adolescence. Due to the rarity, treatment options for anaplastic meningioma in this age group are not clearly outlined., Case: A 15-year-old boy presented with a left forehead swelling with a history of a left frontal tumor. Radiological investigations revealed a dura-based tumor with a large extracranial and a smaller intracranial component. Craniotomy with near-total excision of the tumor was performed. Histopathological examination of the tumor showed features of an anaplastic meningioma. The patient is currently receiving radiotherapy and chemotherapy. However, he has developed scalp swellings while on radiotherapy., Conclusion: Anaplastic meningioma is extremely rare in children. Extensive sampling is required to recognize the meningothelial nature of the tumor and immunohistochemistry helps in making an accurate diagnosis in such cases. Therapeutic interventions in such cases need to be closely monitored due to the aggressive behavior of this tumor.

A 66-year-old man reported a slowly growing tumor on the lateral edge of his left upper eyelid. This lesion was hard but movable on palpation. A neoplasm of the lacrimal gland was suspected. CT showed a highly calcified lesion at the left upper eyelid. Resection of the tumor was performed, which was located just behind the orbital septum and in front of the lacrimal gland. Anatomopathologic investigation of the excised specimen with immunohistochemistry revealed a benign meningioma of a meningotheliomatous type, containing multiple bone elements. An ectopic orbital meningioma is rare, and this is the first case of a unique lateral localization of this lesion. Therefore, it should be included in the differential diagnosis of a lacrimal gland tumor.

Meningiomas are rare in children. Chordoid meningioma is a very rare variant, as only 16 cases in children have been reported. The authors report the first case of a chordoid meningioma in the third ventricle. A 12-year-old boy presented with headache, abnormal behaviors, and ataxia. Brain MR imaging revealed a 2-cm, well-enhanced mass in the third ventricle and hydrocephalus. Positron emission tomography with [18F]fluorodeoxyglucose showed that the mass was hypermetabolic. Gross-total removal of the mass was performed using a left frontal transcortical and transventricular approach. The mass originated from the left caudate head and was connected to the choroid plexus. A chordoid meningioma was diagnosed on the basis of the histological characteristics of the tumor, which was composed of cords and nests of eosinophilic vacuolated cells with an abundant myxoid matrix, similar to the features of a chordoma. A typical focal meningiomatous pattern was observed. The tumor cells were immunoreactive for vimentin and epithelial membrane antigen. The patient's headache and gait disturbance improved after the tumor was removed. The tumor showed no signs of recurrence during 12 months of follow-up.

Only 1-2% of all meningiomas are intraventricular in location. Metastasis from a histologically "benign" meningioma is a rare, but well-documented event. However, there are only four reported cases in the literature of metastatic spread from a purely intraventricular meningioma. The tumors in these reports had a frankly malignant histology or were associated with surgical manipulation and recurrence of the primary lesion. In this report, the authors present a rare case of the concurrent presentation of a histologically benign intraventricular meningioma and a solitary lung lesion which proved to be metastatic meningioma.

Object: Meningioma research has been hindered by the inability to sequentially measure intracranial tumor growth in a cost-effective, efficient manner. Recently, the luciferase gene has been transfected into cancer lines to obtain cells that express the luciferase enzyme, which oxidizes luciferin in a reaction that releases photon energy that can be measured noninvasively by bioluminescence imaging (BLI) systems. The authors describe a mouse model of intracranial meningioma that uses this novel BLI system., Methods: The immortal meningioma cell lines CH-157-MN and IOMM-Lee were transfected with luciferase and neomycin phosphotransferase (LucNeo) and selected with G418. These cells were stereotactically implanted at skull base and cerebral convexity locations in nude mice. Animals were imaged for bioluminescence biweekly, and 5 mice underwent magnetic resonance (MR) imaging. Tumors were harvested for immunohistochemical and ultrastructural analysis., Results: The CH-157-MN-LucNeo and IOMM-Lee-LucNeo cell lines were successfully implanted intracranially in mice. The tumor induction rate for CH-157-MN-LucNeo skull base tumors was 90% (36 of 40 procedures). Statistical analysis of CH-157-MN-LucNeo skull base tumor volume measured on MR imaging correlated with the results of BLI showed an R value of 0.900. The tumors exhibited characteristics of aggressive meningiomas by insinuating along arachnoid planes and invading brain., Conclusions: Noninvasive BLI was successfully used to image intracranial meningiomas in mice. The tumors grew in a fashion similar to that of aggressive meningiomas in humans, and exhibited the microscopic, immunohistochemical, and ultrastructural features characteristic of meningiomas. This animal model overcomes the main obstacle in studying intracranial meningiomas by enabling sequential noninvasive tumor measurement in a cost-effective manner.

While osteoblastoma of the cranial vault is rare, the periosteal form of the tumor is highly unusual, with only one case reported in the English literature. We report on a 24-year-old woman presenting with headache and tinnitus. Magnetic resonance imaging of the brain showed an extra-axial temporal mass with findings that were suggestive of a meningioma. The mass was excised completely, and histological examination revealed a periosteal osteoblastoma arising from the inner surface of the temporal bone and adhering to the dura. The tumor was strongly positive for epithelial membrane antigen, a feature not previously described in osteoblastoma, and one that could lead to a mistaken diagnosis of metaplastic meningioma in a limited sample. A detailed literature review of 40 other reported cases of calvarial osteoblastoma is presented. Apart from being slightly more common in females, calvarial osteoblastoma is similar in all other respects to that arising at conventional skeletal sites. Accurate histological diagnosis of a calvarial osteoblastoma requires adequate sampling of the tumor, including its interface with adjacent structures. Correlation with the radiological findings is crucial for the diagnosis in most cases; however, it is not helpful in differentiating the rare intracranial periosteal variant from a meningioma.

Meningiomas of the skin are rare tumors that can pose considerable diagnostic challenges to the pathologist. This study presents a case of primary cutaneous meningioma in a newly born baby girl that presents with a subcutaneous nodule on the left posterior occipital scalp. A Magnetic Resonance Imaging examination failed to detect any communication between the tumor site and the meninges. The mass was excised and intra -operatively, there was no evidence of connection between the tumor and the underlying tissues. Microscopically, the tumor was composed of banal looking, mitotically inactive spindle-shaped cells with a whorled configuration. Some cells were concentrically arranged around blood vessels. Immunohistochemical studies were positive for epithelial membrane antigen and vimentin. Immunostains for cytokeratin, S-100 protein, vascular (CD34 and CD31) and muscle markers (Desmin and smooth muscle actin) were negative. The diagnosis of cutaneous meningioma was established. A review of literature was presented.

We present a case of intracranial lipomatous meningioma in the parietal convexity in a 64-year-old woman. The mass showed low density on computed tomography, was hyper-intense on T1-weighted magnetic resonance images, and had decreased intensity upon imaging with fat-suppressed sequences. Gross total removal of the tumor was performed. Histopathologically, the tumor was a meningioma with mixed transitional and lipomatous patterns. Immunohistochemically, the meningothelial foci were positive for epithelial membrane antigen (EMA) and vimentin, and negative for S-100 protein. The lipomatous foci were positive for EMA, vimentin, and S-100 protein. The Ki-67 index values of the meningothelial and lipomatous foci were 1.0% and 1.8%, respectively. We review previous reports of lipomatous meningioma and discuss its clinical presentations and pathology.

A 34-year-old woman presented with progressive proptosis of the right eye for 2 years. MRI revealed a well-demarcated mass in the right intraconal space, which was isointense on T(1)- and hyperintense on T(2)-weighted images with bright uniform enhancement. The mass was resected through a lateral orbitotomy. Histopathologic examination revealed cords and clusters of spindle and epithelioid cells embedded in a myxoid matrix, with vacuolated eosinophilic cytoplasm and round nuclei. The tumor cells were diffusely positive for epithelial membrane antigen and vimentin. These findings helped confirm the diagnosis of chordoid meningioma, a rare variant of meningioma with a greater risk of recurrence and aggressive growth. Many of the clinical manifestations and imaging findings were indistinguishable from those of cavernous hemangiomas, solitary fibrous tumors, neurofibromas, and other variants of meningiomas. Given the prognostic significance of chordoid meningioma, extra care and attention should be given during surgery, histopathologic assessment, and follow-up.

Chordoid meningioma is an uncommon histopathological variant of meningioma frequently confused with chordoma. Recurrence is not uncommon. The aim of our study is to present the clinical and pathological characteristics of this entity and a review of the literature. We report two cases of chordoid meningioma occurring in two women aged 47 and 63 years. Both women presented neurological signs without systemic disease. Radiological findings were temporoparietal and temporofrontal lesions with intense enhancement after contrast injection. Complete surgical resection was performed. Histopathologic findings were consistent with chordoid meningioma.

Chordoid meningioma (CM) is a rare histological variant of meningioma and is classified as an atypical meningioma on pattern alone. Herein is described the first case of CM occurring in the jugular foramen. The patient was a 45-year-old woman with a 2 year history of progressive right hearing loss. Magnetic resonance imaging (MRI) demonstrated a large, dumbbell-shaped, homogenously gadolinium-enhanced mass in the right jugular foramen, extending medially to the cerebellopontine angle and caudally into the upper carotid space. Angiographic findings supported a diagnosis of schwannoma. Intraoperatively, the tumor appeared to involve the right glossopharyngeal nerve completely and the vagus nerve incompletely, and was incompletely resected. Microscopically, the tumor consisted predominantly of cords and nests of medium-sized cells with bland cytological features, surrounded by a pale basophilic mucin. Immunohistochemically, the tumor cells demonstrated reactivity for epithelial membrane antigen (membranous) and vimentin, with negative staining for S-100 protein, cytokeratin, CD34, glial fibrillary acidic protein (GFAP), synaptophysin, and chromogranin A. Based on the chordoid histology, an organoid lobular arrangement of the tumor cells, and the location of the tumor (jugular foramen), the differential diagnosis included not only a chordoma but also a paraganglioma (glomus jugulare tumor). Histological identification of typical meningotheliomatous areas, plus selective immunohistochemical panel, is important to establish the correct diagnosis.

Secretory meningiomas are rare histological subtypes of meningiomas with benign biological behaviour. In this study, the authors describe the first case of secretory meningioma with many mitotic figures and brain invasion, and discuss the clinicopathologic features including immunohistochemical staining profile and ultrastructural appearance of this tumour. A case of a 54-year-old man diagnosed with an intracranial tumour located in the left frontal lobe is presented. On pre-contrast CT scans, the tumour was hypodense and the contrast enhancement was marked in the pseudo membrane. The tumour was partially removed. The histological diagnosis was secretory meningioma with many mitotic figures, a high MIB-1 labeling index and a brain invasion.

The histologic distinction between meningiomas and other tumors of the central nervous system occasionally can be difficult. Claudin-1 is a tight junction-associated protein recently shown to be expressed in anaplastic meningiomas. The purpose of this study was to determine whether immunohistochemical staining for claudin-1 could help distinguish meningiomas from histologic mimics, compared with commonly used markers. Tissue sections from 10 meningothelial meningiomas, 20 fibrous meningiomas, 10 atypical meningiomas, 7 solitary fibrous tumors of the meninges, 5 meningeal hemangiopericytomas, and 7 vestibular schwannomas were stained immunohistochemically for claudin-1, epithelial membrane antigen, S-100 protein, CD34, and glial fibrillary acidic protein. In total, 21 (53%) of 40 meningiomas were immunoreactive for claudin-1, whereas none of the other tumors were positive. In contrast, there was considerable overlap in the distribution of the other antibodies evaluated. Claudin-1 seems to be a specific marker for meningiomas in this context. Although its sensitivity is relatively low, claudin-1 may be helpful in a panel of immunostains to distinguish meningiomas from histologic mimics.

Secretory meningiomas constitute a relatively rare subtype of meningiomas, accounting for only 1.1% at our institution, with a 6:1 predominance of female patients. This study aimed to obtain more information about the immunohistochemical characteristics of this histological entity, and to analyse the effects of histological factors such as the presence of mast cells on the radiological evidence of surrounding tumour oedema that frequently occurred in this subtype of meningioma. Fourteen cases of secretory meningioma were examined. Relevant clinical information was obtained from the patient files. Peritumoural oedema was determined either by CT or MRI scans and graded as small, moderate and severe. In order to perform the quantitative evaluation of mast cells in secretory meningiomas in a comparison with other meningiomas, 14 non-secretory meningiomas were randomly selected and used as a control group. The immunohistochemical staining of carcinoembryonic antigen was positive within the secretory droplets and the cells surrounding them in all cases. Ki 67 (MIB 1) proliferative index mean values were 2.4%, indicating low expression in all secretory meningiomas. Moreover, from our statistical analysis, there is no clear-cut pattern of various types of cytokeratins emerging in secretory meningiomas. The secretory meningiomas were characterized by a significantly increased number of mast cells as compared with non-secretory meningiomas of different grades. As the present clinical findings and laboratory results could not confirm a correlation between mast cell density and radiological evidence of oedema, further studies of mediators are warranted.

Lipomatous meningiomas are rarely encountered and are included in the World Health Organization's (WHO) group of metaplastic meningiomas. We report two cases of these tumors. The presenting symptoms were headaches in one case and seizure in the other. Radiologically, these tumors were extra-axial and unique. One tumor displayed fat accumulation, while the other had the appearance of a conventional meningioma. Microscopically, these tumors corresponded to meningothelial and transitional meningiomas containing a variable proportion of adipose tissue composed of mature adipocytes or lipoblasts. Fat content was high in one case and moderate in the other, thus explaining the radiological findings. Expression of epithelial membrane antigen and progesterone receptors was present in meningothelial, adipocyte-like, and lipoblast-like cells. These immunohistochemical results suggest that lipid accumulation in meningioma should be considered a transformation of meningothelial cells rather than a true metaplasia.

Chordoid meningiomas are a rare but increasingly recognized subtype of meningioma. Although some cases have been associated with systemic symptoms, in many instances the clinical features are indistinguishable from those associated with other subtypes of meningioma. Given the prognostic significance of the diagnosis of chordoid meningioma, careful consideration should be given to the diagnosis during histological assessment. The authors describe a rare case of chordoid meningioma in the cervical spinal region.

We analyzed the relation between meningioma and the brain in 50 surgical cases. So-called capsule formation was seen in 20 meningiomas, of which 13 were categorized as thin and 7 as thick. In 21 meningiomas the arachnoid membrane was intact, and 10 meningiomas had no underlying arachnoid membrane. The other 19 tumors showed partial disruption of the arachnoid membrane. The degree of arachnoid disruption correlated with the tumor grade, perifocal edema, pial blood supply on angiography, and tumor size. The existence of brain invasion correlated with the tumor grade and partially with tumor size. In case of invasive tumor, GFAP-positive cells were found deep in the tumor, usually in contact with blood vessels. The axons in gliotic brain often showed degenerative changes such as ballooning or varicose swelling. Meningiomas were usually demarcated by a basement membrane that was collagen type 4 (Col4)-positive. However, atypical and anaplastic meningiomas usually lacked Col4 staining at the interface. In two benign meningiomas that looked like an invasive growth, Col4 staining was seen above the brain. A pia mater-like structure covered the tumor surface in both cases. We could not demonstrate a relation between the expression of matrix metalloproteinase (MMP)-2 or MMP-9 and arachnoid disruption or brain invasion.

Based on clinical and histologic features, differentiating metastatic carcinomas from benign or malignant meningiomas usually is not difficult. Occasionally, however, in some patients without a clinical history of carcinoma, malignant meningiomas can morphologically simulate metastatic carcinoma, necessitating an immunohistochemical study for cytokeratin to make a correct diagnosis. However, the utility of immunohistochemical markers to separate malignant meningioma from metastatic carcinoma has not been investigated. The immunoperoxidase method with antigen retrieval was used to characterize the expression of three cytokeratins (AE1/AE3, CAM 5.2, and Pan cytokeratin), EMA, CEA, Ber-EP4, CD 15, and B72.3 in 12 previously diagnosed malignant meningiomas, 20 benign meningiomas, and 20 metastatic carcinomas. Cytokeratin expression was detected in 75% of malignant meningiomas, 0% of benign meningiomas, and 100% of metastatic carcinomas. While epithelial markers of Ber-EP4, CEA, B72.3 and CD-15 were positive in 90, 80, 70 and 65% of the metastatic carcinoma, respectively, they were negative in all 12 malignant meningioma examined. Vimentin immunoreactivity was seen in all benign and malignant meningiomas, and in 20% of metastatic carcinomas. Our results indicated that cytokeratin is not a reliable immunohistochemical marker to separate a malignant meningioma from metastatic carcinoma. A panel of epithelial markers including Ber-EP4, CEA, B72.3 and CD-15, and vimentin may be needed to separate malignant meningioma from metastatic carcinoma. Cytokeratin expression can be a potential pitfall for confusing a malignant meningioma with a metastatic carcinoma.

A previously well 16-month-old boy presented to Sydney Children's Hospital with generalised seizures. There was no history of neurofibromatosis and no family history. Imaging revealed a well-demarcated, frontal intracranial mass at the grey-white matter junction with surrounding oedema. At operation, the tumour was adherent to the underlying brain on its deep aspect but superficially connected to the dura. There was an associated peritumoural cyst. The tumour was biopsied for intra-operative frozen section opinion and excised in its entirety. The specimen consisted of a 25 x 25 x 17 mm nodule of firm cream tissue and separate fragments. Histologically, the tumour was a meningioma with frequent mitoses, necrosis and brain invasion. Optimal treatment, in view of the recurrence risk, includes complete excision and postoperative irradiation. The latter was deferred because of the young age. At follow-up at 26 months, the child was well and free of disease on MRI scan. Paediatric meningiomas are rare, with very few brain-invasive examples in reported series. In infants and young children, few meningiomas have been reported. There are several notable differences between meningiomas in children and adults. This report illustrates these differences.

Brain oedema is usually associated with intracranial meningiomas in about 50-66%. As underlying causes, different factors like localisation, vascular supply, angiogenic growth factors and histological subtypes are discussed, and its existence is probably multifactorial. We present 11 patients with the rare subtype of secretory meningiomas. Brain oedema was observed in 82%. These tumours are localised mainly at the frontal convexity and at the sphenoid ridge. All 11 patients were female so that hormonal factors also may play a role in the production of peritumoural oedema. The postoperative outcome was good and no recurrences were seen during follow-up., (Copyright 2001 Harcourt Publishers Ltd.)

Microcystic meningioma is a rare variant of meningioma, showing microcystic formations throughout the tumor. To the best of our knowledge, there have been no reports describing cytologic findings of microcystic meningioma. Our case was a 66-yr-old woman with a tumor mass adhered to the dura matter. The crush preparations of a small tissue fragment resected from the mass showed medium- to large-sized, well-cohesive clusters or sheets of uniform tumor cells. The tumor cells did not show a feathering-off pattern. Various-sized cystic spaces were observed within the clusters and sheets. The cytoplasm was relatively abundant, and the nuclear:cytoplasmic ratio was lower than that of classic meningioma. We believe that the cystic spaces within the cell clusters or sheets are characteristic of microcystic meningioma. The cytology of microcystic meningioma seen in our case was similar to that of metastatic adenocarcinoma, but relatively monotonous bland cells, smooth nuclear outline, and inconspicuous nucleoli led us to the diagnosis of meningioma rather than adenocarcinoma., (Copyright 2000 Wiley-Liss, Inc.)

We report a rare case of recurrent meningioma with malignant change and rhabdoid transformation in a 54-year-old woman who presented with severe headache and progressive weakness of the right extremities. The patient had a history of atypical meningioma and had undergone a craniotomy to remove a tumor nine years earlier. We discuss the distinctive morphologic, immunohistochemical staining and ultrastructural features of a recurrent malignant meningioma. A meningioma with rhabdoid transformation may indicate aggressive biologic and clinical behavior of the tumor.

Meningiomas are primary meningeal based tumors of the central nervous system that rarely are located strictly within the fourth ventricle. We report a 72-year-old man operated upon for such a tumor. The pre-operative magnetic resonance images revealed a well circumscribed mass in the fourth ventricle that exhibited a low signal on T1-weighted magnetic resonance images and homogenously enhanced with gadolinium. By light microscopy the tumor was composed of tightly packed spindle cells separated by collagen. Immunohistochemistry showed the tumor cells to be positive for vimentin and epithelial membrane antigen, and negative for glial fibrillary acidic protein. Electron microscopy revealed typical findings of meningioma, including interdigitating cell processes, desmosomes, and intermediate filaments. Although rare, fibroblastic meningioma must be included in the differential diagnosis of a fourth ventricular spindle cell tumor in elderly patients.

We describe a case of meningothelial meningioma with a large number of intranuclear inclusions. Morphologically, these are divided into cytoplasmic inclusions and nuclear vacuoles. The cytoplasmic inclusion has a limiting membrane with cell organelles and filaments. Inclusions of this type are generally eosinophilic, like the cytoplasm. However, there are many inclusions that are more eosinophilic than the cytoplasm or that have a ground-glass appearance. Some of them may contain fine or coarse granules. On the other hand, the nuclear vacuole lacks a limiting membrane and appears empty. In most of the inclusions of this type, there is a faintly basophilic substance in the margin. Generally, the cytoplasmic inclusions are as immunopositive as cytoplasm with vimentin, but some of these cytoplasmic inclusions are more reactive. Under the electron microscope, abnormal aggregation of intermediate filaments is recognized in the cytoplasmic inclusions. It is considered that a strong reaction of cytoplasmic inclusions with vimentin immunostaining is due to abnormal aggregation of intermediate filaments. The present study distinctly demonstrates abnormal localization of intermediate filaments in the cytoplasmic inclusions, and it is suggested that the cytoskeleton participates in the evolution of the cytoplasmic inclusions.

Clear cell meningioma (CCM) is a peculiar variant that differs from conventional meningioma in affecting younger patients, arising more often in spinal or cerebellopontine locations, and showing a higher recurrence rate. Classical meningothelial areas are scarce in these tumors and the differential diagnosis with other neoplasms, particularly metastatic carcinoma, is often difficult. We report a case of clear cell meningioma from the lumbosacral spine in which location, radiologic presentation, light microscopic appearance in initial sampling, and some of the ultrastructural findings were reminiscent of chordoma. The tumor cells were diffusely positive for vimentin and very focally positive for epithelial membrane antigen. Ultrastructural demonstration of interdigitating cell processes joined by numerous desmosomes confirmed the diagnosis of CCM.

A case of meningioma coexisting with both lipomatous and secretory components, the latter characterized by hyaline inclusion bodies, is reported. The neuroradiological features of lipomeningioma are reevaluated, and the possible pathogenetic mechanisms of this unique combination in the present case are discussed.

Background: Ectopic meningiomas arising in the lung are rare. We report here the first multiple primary case diagnosed by intraoperative imprint cytology., Case: Asymptomatic pulmonary nodules, two in the left and three in the right lung, were found in a 61-year-old woman, and video-assisted thoracoscopic surgery was undertaken. Because the largest tumor was diagnosed as a meningioma by intraoperative imprint cytology using an excised biopsy specimen, further resection was not performed immediately. Histopathologically the tumor was characterized by whorled nests of cells accompanied by psammoma bodies intermingled with a fibrous pattern. The diagnosis was a transitional meningioma, positive for vimentin and epithelial membrane antigen and negative for keratin immunohistochemically. All the nodules were subsequently surgically resected and showed a similar cytohistologic appearance. Ultrastructurally the tumor cells demonstrated interdigitation of adjacent plasma membranes with numerous desmosomes and hemidesmosomes, typical of meningiomas. We failed to detect another primary tumor in the nervous system, and at this writing the patient was healthy three years after the operation., Conclusion: Because of the characteristic cytomorphologic features of primary pulmonary meningioma, the cytologic approach provides useful information for therapy.

We report the case of a 25 year old male who presented with a well-circumscribed mass in the infratemporal fossa, without intracranial localisation. On histological examination, this tumor was a transitional type of meningioma. We review the literature and discuss the pathogenesis and the differential diagnosis.

Meningiomas, thought to arise from arachnoid cap cells, are usually attached to the dura. Malignancy is present in approximately 1% of these tumors. The authors report the case of a patient with a malignant meningioma arising from the oculomotor nerve with no dural attachment. The patient presented with a 7-month history of left-sided ptosis and diplopia. Magnetic resonance imaging demonstrated an extrinsic mass compressing the root of the oculomotor nerve at its exit from the midbrain. During surgery, a left-sided subtemporal approach revealed the tumor to be arising from the oculomotor nerve. Histological investigation showed a malignant spindle cell lesion with an immunohistochemical profile that was consistent with malignant meningioma. To the authors' knowledge, this is the first documented case of a malignant meningioma arising from the oculomotor nerve.

A cutaneous meningioma of the external auditory canal occurred in a 48-year-old Filipino woman who had undergone subtotal resection of a dural-based intracranial meningioma at the ipsilateral cerebellopontine angle 36 months previously. Radiologic findings demonstrated a recurrence of intracranial meningioma with surface erosion and heterogeneous densities of the mastoid bone, without extension to the area of the external auditory canal. Meningioma in the external ear canal is extremely rare. To our knowledge, there have been only two previously reported cases, both without intracranial lesion. In this case, the auditory canal lesion may represent either an ectopic meningioma arising from an arachnoid cell rest or an occult direct extension from intracranial menigioma.

Extracranial meningiomas are rare outside the head and neck region. We report a case of primary pulmonary meningioma, initially detected as a radiographic incidental finding, occurring in an asymptomatic 45-year-old woman. Light microscopic examination of both cytologic and histologic preparations was typical of a classical meningioma and included such features as intranuclear pseudoinclusions, psammoma bodies, and cellular whorls. Immunohistochemistry demonstrated tumor cell positivity for vimentin and epithelial membrane antigen, as is characteristic of meningioma. Ultrastructural analysis showed interdigitating cell membranes and desmosomes, with no evidence of basal lamina, neurosecretory granules, or microvilli. On short-term follow-up, the patient is well and has no evidence of a cranial or spinal meningioma. The previous 10 cases reported in the literature had similar characteristics, including a tendency toward occurrence in middle age to older women, asymptomatic presentation, peripheral lung location, and morphologic features. Finally, other conditions in the differential diagnosis and possible histogenesis are discussed.

Background: Secretory meningioma is a rare histologic variant characterized by a unique epithelial differentiation of meningothelial cells resulting in the production of hyaline inclusions. Most previous reports have presented single case observations. The authors selected 31 cases for a clinicopathologic study to characterize this type of tumor further., Methods: Clinical data were compiled and the extent of peritumoral edema was assessed from preoperative computed tomography or magnetic resonance imaging scans. Preparations of surgical specimens of all tumors were studied after both conventional histologic and immunohistochemical preparations were made. Immunostaining was performed by either the avidin-biotin complex method or the alkaline phosphatase-antialkaline phosphatase method using 22 primary antibodies., Results: In the tumor collection used in this study, secretory meningiomas represented 3% of meningiomas. The female-to-male ratio was 9:1. Most tumors were located at the sphenoid ridge or at the frontal convexity, and recurrences were not observed. Eighty-four percent of tumors presented with slight to marked peritumoral edema. The MIB-1 staining index showed a mean of 3.8%. Inclusions and surrounding cells consistently expressed epithelial membrane antigen, cytokeratins, carcinoembryonic antigen, and carbohydrate antigen 19-9. In decreasing frequency, they also contained alpha1-antitrypsin, immunoglobulin (Ig)A, alpha1-antichymotrypsin, IgM, and IgG. Cells positive for vimentin and S-100 did not contain inclusions. All tumors were positive for progesterone receptors. Macrophages were stained with antibodies to factor XIIIa, human leukocyte antigen-DR, and alpha1-antitrypsin. In 64% of cases, tumor vessels lacked expression of glucose transporter protein 1., Conclusions: The classification of secretory meningioma as a distinct variant has been justified on clinical, histologic, and immunohistochemical grounds. The unique epithelial features call attention to the broad spectrum of differentiation properties found in meningiomas.