Metaplastic Meningioma Research Articles

Incidental Metaplastic Primary Pulmonary Meningioma.

Primary pulmonary meningioma is a rare benign tumor usually presenting as a solitary pulmonary nodule or mass. It can be easily misinterpreted as a primary lung tumor or metastases on imaging studies. We present a 54-year-old woman with an incidentally discovered solitary lung nodule, which was diagnosed as metaplastic primary pulmonary meningioma following resection. Metaplastic meningioma is a rare WHO grade 1 meningioma subtype with focal or global mesenchymal differentiation. To the authors' knowledge, primary pulmonary meningioma with mesenchymal differentiation has not been described previously in the English literature.

Metaplastic Meningioma Presenting with Anemia in A Young Boy Case Report and Review of the Literature

Metaplastic Meningioma Presenting with Anemia in A Young Boy Case Report and Review of the Literature

DNA methylation profiling of a lipomatous meningioma: illustrative case.

Lipomatous meningiomas are an extremely rare, benign meningioma subtype subcategorized under metaplastic meningioma in the most recent 2021 update to the World Health Organization classification. They make up less than 0.3% of all meningiomas and, to date, less than 70 cases have been reported in the literature, none of which have undergone molecular profiling. This study aims to promote the utility of molecular profiling to better diagnose these rare tumors. The authors present the first case of a lipomatous meningioma with DNA methylation profiling that both confirmed its benign biology and uncovered unique cytogenetic changes. Molecular characterization of a lipomatous meningioma confirmed its diagnosis as a distinct, benign meningioma subtype and revealed several copy number variations on chromosome 8 and in NF2 and SMARCB1. Here we discuss some of the radiological and histopathological features of lipomatous meningiomas, how they can be used to distinguish from other meningiomas and other similarly presenting tumors, and a brief literature review discussing the pathophysiology and presentation of this rare tumor. This study provides evidence supporting the use of molecular profiling to diagnose lipomatous meningiomas and guide their clinical management more accurately.

Xanthomatous meningioma, a rare histological variant: Case report

Xanthomatous meningioma is a WHO grade I metaplastic meningioma where neoplastic cells contain lipid-filled vacuolated cytoplasm. The origin of xanthomatous meningiomas is believed to be from meningothelial cells but diagnosis remains difficult because of their close resemblance with the histiocytes. Peculiar radiographic features may aid in diagnosis, however, definitive diagnosis requires immunohistochemical staining. We report a case of 43-year-old male with sphenoid wing meningioma revealing xanthomatous changes and received treatment as grade 1 meningioma. Though the exact pathophysiology remains unknown, we believe focal or gross metaplastic changes lead to transformation of tumor cells into the xanthomatous subtype. Authors discuss this interesting a rare histologic variant with discussion of the relevant literature.

Fronto-orbito-ethmoidal intradiploic meningiomas: A case study with systematic review

Background: Primary intradiploic meningiomas, extra-axial tumors arising primarily in the skull, are rare. The authors reported a complex case of intradiploic intraosseous metaplastic meningioma of the left medial wall and orbital roof with the left frontal sinus invasion and left ethmoidal body bone substitution. The authors also conducted a systematic review concerning diagnosis and management of patients affected by purely calvarial intradiploic meningiomas along with a focus on fronto-orbito-ethmoidal ones.Methods: A literature search was conducted using PubMed and Scopus databases according to preferred reporting items for systematic reviews and meta-analysis statement and with the following Mesh terms: Intradiploic, intraosseous, calvarial, and meningioma. Eligibility criteria were limited by the nature of existing literature on intradiploic meningiomas, consisting of only case series, and case reports.Results: A total of 128 published studies were identified through our search. 41 studies were included in this systematic review, 59 patients with a female/male ratio of 1.2/1. The mean age of the patients is of 47.69 years (range 3–84 years). Only seven out of 59 patients (11.9%) presented a complex intradiploic meningioma located in fronto-orbito-ethmoidal region like our case. In almost all patients, a gross-total resection was performed (96.6%) and only in two patients (3.4%) a subtotal resection was achieved.Conclusion: The authors shared this successfully treated case to add to the overall clinical experience in the management of this rare subtype tumor, with the hope that more studies are conducted to further address the mechanism of intradiploic meningiomas development.

Two distinct case reports with foamy cell and differential diagnosis: Xanthomatous meningioma and review of literature

Meningiomas are the most common primary intracranial tumor thought to derived from arachnoidal cap cells in the meningeal coverings of the spinal cord and brain. The current WHO classification, published in 2016, includes nine different subtypes of grade 1 meningiomas, three different subtypes of grade 2 meningiomas, and three different subtypes of grade 3 meningiomas. Metaplastic meningioma is a rare variant which shows focal or diffuse mesenchymal tissue component. Xanthomatous meningioma which has foamy cell changes is a quite rare variant of metaplastic meningioma. Two patients, 54 and 59 years old, who applied to our clinic with similar symptoms, were operated for meningioma. Histopathological examination of their biopsy showed that neoplastic cells had oval-round nuclei and eosinophilic cytoplasm. In xanthomatous meningioma, some neoplastic cells had clear vacuolated cytoplasm (foamy cells). In microscopic examination of resection material in one of these patients, cells in some areas of the tumor had clear vacuolated cytoplasm (foamy cells). These neoplastic cells were scattered among other meningothelial cells and they were positive for EMA. To the best of our knowledge, until today there have been only 14 reported xanthomatous meningioma cases in English literature. Here, we aimed to discuss the pathogenesis and differential diagnosis of xanthomatous meningioma in two different cases

Intracranial Metaplastic Meningioma : Clinical and Radiological Characteristics of 11 Cases.

ObjectiveMetaplastic meningioma is an extremely rare subtype of World Health Organization (WHO) grade I meningioma. It has distinctive histological subtypes according to its own mesenchymal components. Owing to its scarcity, clinical or radiological features of a metaplastic meningioma are poorly described. MethodsBetween 2004 and 2018, we analyzed total 1814 cases surgically proven meningioma for 15 years. Among them, metaplastic meningioma was diagnosed in 11 cases. Magnetic resonance images were taken for all patients, and computed tomography scan was taken for 10 patients. ResultsWHO grade I meningiomas were 1376 cases (75.9%), 354 cases (19.5%) in WHO grade II, and 84 cases (4.6%) in WHO grade III meningiomas. Metaplastic meningioma was 11 cases as 0.8% of WHO grade I meningioma and 0.6% of entire meningiomas for 15 years. Among the entire 11 metaplastic meningiomas, five tumors (45%) were diagnosed as a lipomatous subtype with rich fat components, four (36%) as an osseous subtype with extensive bone formation and two (18%) as a xanthomatous subtype. There was no cartilaginous subtype metaplastic meningioma in our study. Lipomatous and osseous metaplastic meningioma have peculiar radiological characteristics according to mesenchymal components. ConclusionWe investigated a rare metaplastic meningioma subtype based on our 15-year surgical experience with meningiomas. Further investigation will be necessary for the clear clarification of tumor nature of this rare tumor.

Expression of mucin-4 in meningiomas and its diagnostic significance

Objective: To investigate the expression of mucin-4 (MUC4) in meningiomas. Methods: Totally 258 cases of meningiomas and 165 cases of other brain tumors were collected from the First Affiliated Hospital of China University of Science and Technology (Anhui Provincial Hospital) from 2011 to 2017. MUC4, EMA, PR, SSTR-2 protein expression was detected by immunohistochemistry, and their expression in meningiomas and other tumor tissue was compared. Results: The 258 patients with meningioma included 85 males and 173 females, with a mean age of 69 years. Among the meningiomas, 192, 54 and 12 were WHO grades Ⅰ, Ⅱ and Ⅲ respectively. The overall expression rate of MUC4 in meningiomas was 67.8% (175/258), including 46/46 (100.0%) in meningothelial meningiomas, 3/3 in secretory meningiomas, 44/45 (97.8%) in angiomatous meningiomas, 37/41 (90.2%) in atypical meningiomas, 3/4 in metaplastic meningiomas, 2/3 in microcystic meningiomas, 7/11 in psammomatous meningiomas, 7/11 in chordoid meningiomas, 14/28 (50.0%) in transitional meningiomas, 1/2 in clear cell meningiomas, 1/2 in papillary meningiomas, 4/9 in anaplastic meningiomas, 7/52 (13.5%) in fibrous meningiomas, and 0/1 in rhabdoid meningiomas. In addition, MUC4 was expressed in 44 EMA negative meningiomas and in four SSTR-2 negative meningiomas. PR, EMA, SSTR-2 were expressed in 149 cases (57.7%), 173 cases (67.1%), 235 cases (91.1%) of meningiomas, respectively. MUC4 was not expressed in other tumors in the central nervous system, including schwannomas, neurofibromas, solitary fibrous tumors/hemangiopericytoma (SFT/HPC), hemangioblastoma, gliomas and ependymomas. Conclusion: MUC4 is widely expressed in meningiomas and has great value in distinguishing meningiomas from other non-meningeal epithelial tumorsof the central nervous system.

Thoracic psammomatous meningioma with osseous metaplasia: a controversial diagnosis of a case report and literature review

BackgroundSpinal psammomatous meningioma with calcification is commonly observed, but distinctive osseous differentiation rarely occurs.Case presentationHere, we described a 52-year-old female complaining of chronic back pain for 5 years. CT and MRI examinations revealed an intradural extramedullary mass at the T4 level. The tumor was meticulously excised en bloc. Under the microscope, the tumor was found to be composed of conspicuous calcified psammoma bodies with remarkable immature bone formation. A primary diagnosis of psammomatous meningioma was made based on the recent WHO classification of tumors of the CNS, whereas other pathologists focused on the osseous components and preferred metaplastic meningioma as the proper subtype. A literature review was conducted, and only five cases have been reported with the same histopathological condition. Experts finally reached a consensus based on the acknowledged notion of the preferential diagnosis of psammomatous meningioma, as well as the current evidence and popular opinion that ossification is generated from osteogenic differentiation of pluripotent cells rather than the accumulation of psammoma bodies.ConclusionsA final diagnosis of psammomatous meningioma with osseous metaplasia was made. The rigid and adherent features complicate total resection of the tumor and increase the risk of neurologic deficits.

Intracranial cystic meningiomas: A series of six patients

ObjectiveAlthough meningiomas are the most common primary non-glial intracranial tumors, cystic meningiomas are quite rare. This study presents six cases in order to discuss the radiological and pathological features of cystic meningiomas. Patients and methodsSix patients with cystic meningiomas were included in the study. All patients underwent a cranial computed tomography scan and magnetic resonance imaging (MRI) evaluation, pre- and postoperatively. ResultsAll patients presented with long standing headache dating back at least two years. There was no gender predominance in our series. Radiological evaluation revealed two parasagittal and two convexity meningiomas located at the frontal region. Two lesions were located at the tuberculum sellae and the foramen magnum. All of the tumors were totally excised (Simpson Grade I or II). Pathology results included meningothelial meningioma in three patients, angiomatous meningioma in two patients, and metaplastic meningioma in one patient. In two patients, the cystic meningiomas were resected with the use of sodium fluorescein (Na-Fl) under a YELLOW 560nm microscope filter. Na-Fl was found to be very useful in demonstrating the brain–tumor interface, and it was especially effective in resecting the cyst wall of the peritumoural cystic meningiomas. None of the patients had any complications, and no recurrences were noted in any of the patients within the mean follow-up period of 51 months (range: 16–102 months). ConclusionIt is important to note MRI changes specific to cystic meningioma and include meningiomas in the differential diagnosis of intracranial cystic lesions. The use of sodium fluorescein (Na-Fl) under a YELLOW 560nm microscope filter is a useful tool to differentiate the brain-tumor interface, as well as to identify the cyst wall in order to fully resect the tumor with the cystic component to avoid recurrence and achieve better clinical results.

Intracranial cystic meningiomas: A series of six patients.

Although meningiomas are the most common primary non-glial intracranial tumors, cystic meningiomas are quite rare. This study presents six cases in order to discuss the radiological and pathological features of cystic meningiomas. Six patients with cystic meningiomas were included in the study. All patients underwent a cranial computed tomography scan and magnetic resonance imaging (MRI) evaluation, pre- and postoperatively. All patients presented with long standing headache dating back at least two years. There was no gender predominance in our series. Radiological evaluation revealed two parasagittal and two convexity meningiomas located at the frontal region. Two lesions were located at the tuberculum sellae and the foramen magnum. All of the tumors were totally excised (Simpson Grade I or II). Pathology results included meningothelial meningioma in three patients, angiomatous meningioma in two patients, and metaplastic meningioma in one patient. In two patients, the cystic meningiomas were resected with the use of sodium fluorescein (Na-Fl) under a YELLOW 560nm microscope filter. Na-Fl was found to be very useful in demonstrating the brain-tumor interface, and it was especially effective in resecting the cyst wall of the peritumoural cystic meningiomas. None of the patients had any complications, and no recurrences were noted in any of the patients within the mean follow-up period of 51 months (range: 16-102 months). It is important to note MRI changes specific to cystic meningioma and include meningiomas in the differential diagnosis of intracranial cystic lesions. The use of sodium fluorescein (Na-Fl) under a YELLOW 560nm microscope filter is a useful tool to differentiate the brain-tumor interface, as well as to identify the cyst wall in order to fully resect the tumor with the cystic component to avoid recurrence and achieve better clinical results.

Role of MR Morphology and Diffusion-Weighted Imaging in the Evaluation of Meningiomas: Radio-Pathologic Correlation

Preoperative differentiation of benign, atypical and malignant meningiomas would significantly help in surgical planning and treatment. The aim of this study is to look at radio-morphologic behavior of various histopathological types and grades of meningiomas and their diffusion characteristics. We performed an analytical cross-sectional study including all patients operated on for meningiomas at our hospital during January 2016 to July 2018. We studied 38 meningiomas in 38 patients aged 14 to 73 years old. All patients underwent MRI prior to surgery, including diffusion-weighted sequences, in a 1.5T scanner. Signal intensity in T2-weighted images, diffusion-weighted images (b=0, 90 and 1,000), and Apparent Diffusion Coefficient maps within the tumors and in the normal parietal white matter as a reference were evaluated. In the histological study, cellularity, proliferation index, histological grade, and cerebral invasion were evaluated. There was female predilection with male:female ratio of 1:2.4. Most meningiomas were supratentorial with most common origin being parafalcine and convexity. Of the 38 meningiomas, 31 were WHO grade I, 6 were WHO grade II (atypical) and one was WHO grade III (anaplastic). Among various tumors' behaviors, incomplete CSF cleft, pial invasion and parenchymal invasion were significantly high in high-grade tumors. Similarly, tumors showing pial invasion, breached tumor-brain interface, no capsular enhancement and parenchyma invasion showed significantly low NADC. Mean ADC value was 0.722±7.7x10-3 mm2/s (normalized ADC 0.9±0.1) in the atypical group and 0.876±24.56x10-3 mm2/s (normalized ADC 1.11±0.31) in the typical group. No statistically significant differences of ADC/NADC were found between histologic subtypes. Two subtypes of typical meningiomas, metaplastic and angiomatous meningioma had the highest values in the ADC maps. MR morphology like pial invasion, breached tumors brain interface, parenchymal invasion can predict aggressiveness and atypical nature of meningiomas. Meningioma shows moderately restricted diffusion. The signal on the ADC map is associated with tumors cellularity and aggressiveness suggesting its usefulness for predicting the histological grade.

Ossified Metaplastic Spinal Meningioma Without Psammomatous Calcification: A Case Report

Meningiomas constitute approximately 25% of primary spinal cord tumors, and 1% to 5% are calcified. Ossification is a rare event and the etiology of ossification in meningiomas is not well known. We present the case of a 29-year-old female with a rare case of ossified thoracic spinal metaplastic meningioma. The tumor was successfully resected, and pathology confirmed ossified metaplastic meningioma. On histopathological examination, only mature bone tissue and tumor cells were present in the region containing no psammoma bodies, suggesting that the tumor cells had transitioned to mature osteocytes.

Metaplastic Meningioma Overspreading the Cerebral Convexity

Meningioma is relatively common, benign, and extra-axial tumor accounting for about 20% of primary brain and spinal cord tumors. The World Health Organization (WHO) classified these tumors into Grade I (benign), Grade II (atypical), and Grade III (anaplastic) meningioma. Grade I meningioma which is slowly growing tumor and have some rare subtypes. Among them, metaplastic subtype is defined as a tumor containing focal or widespread mesenchymal components including osseous, cartilaginous, lipomatous, myxoid or xanthomatous tissue, singly or in combinations. We report a rare metaplastic meningioma overspreading nearly whole cerebral convexity from main extra-axial tumor bulk in the parietal lobe.

Ossified Intracranial Meningiomas: Description of the First Series of Cases and Review of the Literature

Metaplastic meningiomas are characterized by mesenchymal differentiation with formation of bone, cartilage, fat, or xanthomatous elements. However the presence of extensive areas of ossification is rare in meningiomas. In addition, intracranial location of ossified meningiomas is uncommon. Surgical management represents the optimal treatment for ossified meningiomas, but ossification may interfere with surgery and condition outcome. By reviewing patient records and contacting patients, families, and referring physicians, the following information was gathered: age, sex, tumor location, clinical presentation, preoperative and postoperative functional status, and surgical data. Each surgical specimen had been formalin-fixed, paraffin-embedded, and cut into parallel 4-μm-thick sections for histological evaluation. Our literature search identified 8 cases, all of whom had undergone surgical treatment. Histopathological analysis revealed the presence of disorganized bone spicules with solitary oval osteocytic nuclei and lined by osteoblasts, with clear evidence of bone tissue in at least 50% of tumor tissue. Here we present the largest series, to our knowledge, of surgically treated intracranial ossified meningiomas reported to date. The mechanism of ossification in these meningiomas remains unclear, and various hypotheses have been formulated. Complete lesion removal, or subtotal debulking in those cases characterized by tenacious adherences to vascular structures and/or critical areas, may represent the optimal treatment.

Pathological correlation of Magnetic Resonance Imaging features in a classical case of lipomatous meningioma

Meningiomas are common tumors, constituting about 20% of all primary brain tumors.[4] The histological subtype of lipomatous meningioma, resulting from lipid accumulation within meningothelial cells, is a well-described but uncommon entity, representing approximately 0.3% of meningiomas.[2,3] In the World Health Organization (WHO) classification of tumors of the nervous system (2000), meningiomas with lipomatous changes were classified as metaplastic meningiomas (WHO Grade 1), and it has been documented that the clinical features, surgical management, and prognosis of lipomatous meningiomas are no different from those of other WHO Grade 1 meningiomas.[2] We report the case of a middle-aged women presenting with magnetic resonance imaging (MRI) features of a classical “lipomatous” meningioma and correlate the radiological findings with the histopathological features of this uncommon tumor. A 44-year-old female presented with history of long-standing generalized tonic-clonic seizures of 9 years duration on antiepileptic medications. MRI of the brain revealed a well-demarcated, extra-axial, dural-based, right anterior one-third, parasagittal lesion with predominant areas of intrinsic T1- and T2-weighted hyperintensity [Figure ​[Figure1a1a and ​andb].b]. Hyperostosis of the overlying calvarium was evident. On fat-suppressed fluid attenuation inversion recovery (FLAIR) images, the areas of T1-weighted hyperintensity were suppressed that corresponded to the fat content [Figure 1c]. Moderate edema was evident in the underlying right frontal lobe. On susceptibility weighted imaging, extensive susceptibility (or blooming) was noted within the lesion [Figure 1d]. Postcontrast T1 magnetization prepared rapid gradient-echo axial and sagittal images revealed intense heterogeneous enhancement within the lesion with a dural tail [Figure ​[Figure1e1e and ​andf].f]. The patient underwent right frontal parasagittal craniotomy and Simpson Grade 1 excision of the tumor. The tumor on gross appearance was bright yellow and greasy [Figure 2a]. Histopathology revealed large lobules of mature adipose tissue within which were nesting islands of meningothelial cells forming whorls [Figure ​[Figure2a2a–c], characteristic of a metaplastic (lipomatous) meningioma. Fine intracellular vacuolation was evident within meningothelial cells [Figure 2d]. On close examination, these vacuolations were highlighted on Oil red O stain, confirming its neutral lipid nature [Figure 2d, inset]. At follow-up (1 year), patient is asymptomatic. Figure 1 Magnetic resonance imaging findings in a classical case of lipomatous meningioma. (a) T1-axial, (b) T2-axial, (c) fluid attenuation inversion recovery-axial, (d) susceptibility weighted imaging-axial, (e) T1 magnetization prepared rapid gradient-echo-axial, ... Figure 2 (a) Gross appearance of the tumor that is bright yellow and greasy; (b) scanner view of tumor reveals large lucent areas (*) separating islands of tumor cells; (c) microscopy reveals lobules of mature adipose tissue (*) separating whorls of meningothelial ... Lipomatous meningioma is a subtype of metaplastic meningioma, which was first described by Bailey and Bucy in 1931.[4] On imaging, lipomatous meningiomas have characteristic MRI findings, which, if taken into consideration, can provide preoperative diagnosis of this uncommon entity.[1,3,5] The tumor shows high intensity on T1- and T2-weighted MRI and the high-intensity area on T1-weighted MRI is changed to a low-intensity area on fat-suppressed T1-weighted imaging. Despite this, in the majority of cases, lipomatous meningioma is not diagnosed preoperatively and is often a histopathological diagnosis.[4] The preoperative differential diagnoses considered, in our case, were lipoma, dermoid cyst, teratoma, or xanthomatous meningioma. The classical “dural tail” sign, intense contrast enhancement of the lesion, and hyperostosis of the overlying calvarium were highly suggestive of meningioma; the suppression of T1-weighted hyperintense areas on FLAIR imaging indicated the lipomatous nature of the meningioma. Our report highlights the distinct MRI findings correlating with characteristic histopathological findings in a “classical case” of lipomatous meningioma. Financial Support and Sponsorship Nil. Conflicts of Interest There are no conflicts of interest.

A rare intracranial tumor consisting of malignant anaplastic and papillary meningioma subtypes.

Sir, I read with great interest the paper by Kochanski et al.[2] describing a case of a rare intracranial tumor consisting of malignant anaplastic and papillary meningioma subtypes. As mentioned, multiple intracranial meningiomas and meningiomas showing collision with other intracranial tumors such as astrocytoma and metastatic tumors are well known pathologies. Indeed, coincidence of meningiomas with different radiological findings and histological types are very rare entities. We have previously reported a coincidence of two intracranial meningiomas—a myxomatous metaplastic meningioma (myxoid meningioma) grade 1 (WHO-93) and a psammamotous meningioma grade 1 (WHO-93)—in a 65-year-old man.[1] The tumors were located on the greater wing sphenoid bone and at the level of the precentral gyrus in the left temporoparietal region, respectively. The tumor that was diagnosed as myxoid meningioma was showing hyperintensity in T2-weighted magnetic resonance imaging sequences; and the other tumor was showing hypointensity in all pulse sequences. Multiple meningiomas with the same histopathological diagnoses with multicentric localizations may be due to spreading via cerebrospinal fluid or venous structures; however, the origin of the multiple tumors of different histological type should have independent pathogenesis. In the presence of lesions with different imaging features and/or different operative findings suggestive of separate histological diagnosis, the removal of all components and examination of the whole surgical specimens have more importance. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Easily misdiagnosed metaplastic meningioma: one case report and review of literature

Objective Metaplastic meningioma is rare lesion which is very difficult to diagnose clinically, and is easy to be misdiagnosed. This article aims to reveal the clinical manifestations and histopathological features of this disease. Methods One case of ossification metaplastic meningioma was reported and the relevant literatures were reviewed. Results A 17-year-old female patient showed paroxysmal stiffness accompanied by convulsion of extremities, headache, vomiting and fever. Cranial CT scan demonstrated an irregular low-density signal in the right frontal and parietal lobes. The lesion did not have a clear boundary, and there was a calcificated high-density signal inside it. The size of the lesion was about 2 cm × 1.80 cm × 1.70 cm. Cranial MRI scan showed a tumor with size of 2.40 cm × 2.10 cm × 2 cm, located in the right frontal and parietal lobes, and there was large edema around the lesion. A resection was performed, and a lesion was found in the right frontal and parietal parenchyma, whose one side was close to the cerebral pia mater and did not invade into the dura and the skull. The tumor was yellow, in irregular shape, and had clear boundary, with hard texture and rich blood supply. Its size was about 3 cm × 2.50 cm × 2 cm. There was extensive ossification and calcification within the tumor under microscope. Tumor cells were flaky and like small nests, which were distributed in the mesh?like arranged trabecular bone. The immunohistochemical staining showed that epithelial membrane antigen (EMA), progesterone receptor (PR), vimentin (Vim) and Bcl-2 were positive for tumor cells with Ki-67 labeling index being about 6%. Conclusions Metaplastic meningioma has various metaplastic components and its imaging features are also various. However, it could be diagnosed and identified from other similar tumors by histopathological observation and immunohistochemical staining. doi: 10.3969/j.issn.1672-6731.2014.08.010

Lateral ventricular cystic meningioma: 2 rare case reports.

Cystic meningioma is an uncommon meningioma variant that is often difficult to distinguish from other intra-axial tumors, including necrotic gliomas. Cystic meningiomas located in the ventricle are particularly rare and may be misdiagnosed with other brain tumors, including ependymoma, choroid plexus papilloma and neurocytoma, due to its location. The present study discusses two cases of lateral ventricular meningiomas, which exhibited intratumoral or peritumoral cystic changes on magnetic resonance imaging scans. The two patients underwent surgical treatment and histological examination confirmed one case of metaplastic meningioma and the other case of psammomatous meningioma. The two patients were middle-aged females and had been misdiagnosed prior to surgery. Although this clinical entity is rare, the diagnosis of meningioma should be considered, particularly in middle-aged female patients.

Spinal metaplastic meningioma with osseous differentiation in the ventral thoracic spinal canal.

Ossified meningioma is classified histologically as a phenotype of metaplastic meningioma, and it is extremely rare. There are only 12 cases involving ossified spinal meningiomas in the literature. We present the case of a 61-year-old female with a primary tumor within the ventral spinal canal at T12. Although we performed a total tumor excision using an ultrasonic bone aspirator, a temporary deterioration of motor evoked potentials (MEPs) was observed during curettage with a Kerrison rongeur. The neurologic findings worsened immediately after surgery. Histologically, the tumor was diagnosed as a metaplastic meningioma with osseous differentiation. In order to avoid spinal cord injury, great care must be taken when removing an ossified meningioma located on the ventral spinal cord.