Meningioma mimics: five key imaging features to differentiate them from meningiomas

Primary central nervous system lymphoma: Imaging features and differential diagnosis

Primary central nervous system lymphoma (PCNSL) represents 5% of malignant primary brain tumors. The clinical presentation typically includes focal neurological symptoms, increased intracranial pressure, seizures, and psychiatric symptoms. Although histological examination remains the gold standard for diagnostic confirmation, non-invasive imaging plays a crucial role for the diagnosis. In immunocompetent individuals, PCNSL usually appears as a single, well-defined, supratentorial lesion with a predilection for periventricular areas, iso- or hypointense on T1- and T2-weighted magnetic resonance imaging, with restricted diffusion, slightly increased perfusion, and homogenous gadolinium-enhancement. Differential diagnoses include high-grade glioma and pseudotumoral demyelinating disease. In immunocompromised patients, PCNSL may present as multiple lesions, with a higher likelihood of hemorrhage and necrosis and less restricted diffusion than immunocompetent individuals. Differential diagnoses include neurotoxoplasmosis, progressive multifocal leukoencephalopathy, and cerebral abscess. Atypical forms of lymphoma are characterized by extra-axial lymphoma, lymphomatosis cerebri, and intravascular lymphoma. Extra-axial lymphoma presents as single or multiple extra-axial dural lesions with diffuse leptomeningeal contrast-enhancement. Lymphomatosis cerebri appears as an infiltrative and symmetric lesion, primarily affecting deep white matter and basal ganglia, appearing hyperintense on T2-weighted imaging, without significant contrast-enhancement or perfusion changes. Intravascular lymphoma presents as multiple rounded or oval-shaped "infarct-like" lesions, located cortically or subcortically. This study aims to highlight the imaging characteristics of PCNSL, focusing on magnetic resonance imaging and its differential diagnosis.

Cystic meningiomas: A complex diagnostic challenge and clinicopathological insights from a unique case presentation

Meningiomas present diverse clinical and radiological characteristics, with cystic formations constituting a lesser subset but posing significant diagnostic hurdles. We explore the complexities of cystic meningiomas through a distinctive case, highlighting the challenges in diagnosis and management due to their variable presentations. A 54-year-old female from Bengaluru, Karnataka, initially presented with transient memory disturbances. Brain MRI revealed a sizable left frontal cystic lesion exerting a mass effect and midline shift. However, rapid neurological decline led to an urgent surgical intervention via decompressive craniectomy unveiling unique intraoperative findings and with subsequent histopathological documentation of a Grade WHO 1 cystic meningioma. Cystic meningiomas present intricate diagnostic challenges resembling other intracranial lesions. Various classification systems attempt to categorize these tumors based on their imaging and histopathological characteristics. Despite this, atypical clinical manifestations often lead to misdiagnoses, necessitating a comprehensive approach to differential diagnosis. Further research is crucial to unravel the mechanisms underlying these tumors' cystic changes for improved diagnostic accuracy and tailored therapeutic interventions.

Endoscopic-Assisted Microsurgical Meningioma Resection in the Skull Base via Minicraniotomy: Is There a Difference in Radicality and Outcome between Anterior Skull Base and Posterior Fossa?

Background: Keyhole-based approaches are being explored for skull base tumor surgery; aiming for reduced complications while maintaining resection success rates. This study evaluates skull base meningiomas resected using an endoscopic-assisted microsurgical keyhole approach, comparing outcomes with standard procedures. Methods: Between 2013 and 2019; 71 out of 89 patients were treated using an endoscopic-assisted microsurgical procedure. A total of 42 meningiomas were localized at the anterior skull base and 29 in the posterior fossa. The surgical techniques and use of an endoscope were analyzed and compared in terms of complications, surgical radicality, outcome, and recurrences in the patients' follow-up. Results: The two different cohorts yielded similar rates of GTR (anterior skull base: 80% versus posterior fossa: 82%). The complication rate was 31% for the posterior fossa and 16% for the anterior skull base. An endoscope was used in 79% of all cases. Tumor remnants were detected by means of endoscopic visualization in 58.6% of posterior fossa and 33% of anterior skull base meningiomas. The statistical analysis revealed significantly higher benefits from endoscope use in the posterior fossa cohort (p < 0.05). Conclusions: The results revealed that endoscopy was beneficial in both locations. The identification of remnant tumor tissue and the benefit of endoscopy were clearly higher in the posterior fossa. Endoscopic assistance is a very helpful tool for increasing radicality, providing a better anatomical overview during surgery, and better identifying remnant tumor tissue in skull base meningioma surgery.

Advanced Meningioma Imaging

Noninvasive imaging methods are used to accurately diagnose meningiomas and track their growth and location. These techniques, including computed tomography, MRI, and nuclear medicine, are also being used to gather more information about the biology of the tumors and potentially predict their grade and impact on prognosis. In this article, we will discuss the current and developing uses of these imaging techniques including additional analysis using radiomics in the diagnosis and treatment of meningiomas, including treatment planning and prediction of tumor behavior.

Usefulness of a Rim-Enhancing Pattern on the Contrast-Enhanced 3D-FLAIR Sequence and MRI Characteristics for Distinguishing Meningioma and Malignant Dural-Based Tumor

BACKGROUND AND PURPOSE

Meningiomas are the most common type of extra-axial dural-based tumors; however, malignant dural-based tumors can mimic meningiomas on imaging. The aim of this study was to determine the efficacy of differentiating meningiomas from malignant dural-based tumors by using rim-enhancement patterns on a contrast-enhanced FLAIR sequence and MR imaging characteristics.

MATERIALS AND METHODS

This retrospective study included 102 patients with meningiomas and 31 patients with malignant dural-based tumors who underwent pretreatment MR imaging. The rim-enhancement patterns on contrast-enhanced FLAIR and MR imaging characteristics, including the dural tail sign, hyperostosis, bony destruction, leptomeningeal enhancement, peritumoral edema, T2-weighted signal intensity, and tumor enhancement were evaluated.

RESULTS

Complete rim enhancement of the tumor-brain interface on contrast-enhanced FLAIR (contrast-enhanced-FLAIR rim sign) was present in most meningiomas (91/102, 89.2%) and at significantly greater frequency than in malignant dural-based tumors (2/31, 6.5%) (P  < .001). Complete contrast-enhanced FLAIR rim enhancement provided high sensitivity (89.2%), specificity (93.5%), and accuracy (90.2%) for diagnosing meningioma. Additionally, hyperostosis was an MR imaging characteristic that suggested a diagnosis of meningioma. In contrast, bony destruction with cortical breakthrough and leptomeningeal enhancement suggested malignant dural-based tumors. There were limitations of meningiomas of <2.0 cm or at cavernous sinus locations that did not demonstrate contrast-enhanced FLAIR rim enhancement.

CONCLUSIONS

The rim-enhancement pattern on contrast-enhanced FLAIR could help differentiate meningiomas and malignant dural-based tumors. The presence of complete rim enhancement on contrast-enhanced FLAIR was a robust predictive sign for meningioma.

The NXDC-MEN-301 Study on 5-ALA for Meningiomas Surgery: An Innovative Study Design for the Assessing the Benefit of Intra-Operative Fluorescence Imaging

BACKGROUND

5-aminolevulinic acid (5-ALA; Gleolan^TM, NX Development Corps., Lexington, USA) is approved for fluorescence-guided resections of suspected malignant gliomas. Experience has demonstrated that meningiomas also show fluorescence, which may be a useful surgical adjunct. We present an innovative design for a multi-center, prospective study to determine the clinical safety and potential benefit of fluorescence-guided resection of meningiomas with utmost bias reduction.

METHODS

All patients with suspected meningioma (all grades) receive Gleolan^TM 20 mg/kg 2-4 h prior to surgery supported by fluorescence excitation from a blue light source (Blue400, Zeiss Meditech, Oberkochen, Germany; FL400, Leica Microsystems, Heerbrugg, Switzerland). Surgeons are asked whether a residual tumor can be observed to fluoresce under blue light (BL) after the tumor is no longer recognizable using conventional illumination at the end of surgery. In addition, when faced with tissues of uncertain tissue type (so-called "indeterminate" tissue), this study records how often surgeons make a correct decision based on fluorescence and how this influences surgical strategy. The primary endpoint is the percentage of patients in whom one of these two benefits are observed. Other endpoints include the diagnostic accuracy of fluorescence compared to white light (WL) versus correlative histology. For bias reduction, pertinent data are derived from surgical videos reviewed by independent reviewers blinded to surgeons' assessments of tissue type and fluorescence status. Data will be included from approximately 100 study participants completing the study at approximately 15 centers in the United States, Germany, and Austria.

RESULTS

As of May 2022, 88 patients have completed the study. No adverse safety signal has been detected.

CONCLUSIONS

Preliminary data confirm the feasibility of our study design. Accrual is targeted for completion in the third quarter of 2022.

Case Report: Creeping Growth in Lymphoplasmacyte-Rich Meningioma-A Radiologic Variant

Lymphoplasmacyte-rich meningioma (LRM) is a rare histologic subtype of meningioma. Creeping-growth pattern is uncommon in meningioma, and the mechanism is unclear. Here, we report a 44-year-old man presented with extremities weakness for 2 months and incontinence for 2 weeks. Head and neck MRI revealed diffuse creeping-growth nodular meningeal masses with skull base, tentorium, sella area, and C1-6 vertebral plane involvement. An operation was carried out, cervical and lower clivus part of the lesion was resected, but gross total resection could not be achieved due to the widespread lesions. Pathologic examination revealed the diagnosis of LRM. The patient is free from progression clinically 3 months postoperatively. We also conducted a systematic literature review about LRM with creeping-growth pattern. A total of only nine cases (including the present case) of creeping-growth LRMs were included and analyzed in terms of clinical manifestations, radiological features, treatment, and outcome. LRMs show a higher rate (7.5%) of creeping-growth pattern than other types of meningiomas. The average creeping length of all creeping-growth LRMs was 11.4 ± 10.9 cm (range, 3–30 cm). Most cases (66.7%) had obvious peritumoral edema. Total removal rate is low (33.3%), and two of them (22.2%) received biopsy, followed by steroids treatment (or further immunosuppressive drugs therapy) and radiotherapy. The recurrence rate is higher than conventional LRMs (22.2 vs. 11.3%), and one patient (11.1%) died 11 months after treatment. Creeping-growth pattern in LRM may be considered as a general radiologic variant. The recurrence rate is higher compared with LRM with round/swelling pattern. We speculated that the pathogenesis of creeping growth in LRM may be associated with damage of lymphatic systems of the central nervous system.

Spheno-orbital Lesions-A Major Review of Nonmeningioma Causes

PURPOSE

To review the imaging features of the broad range of nonmeningioma lesions of the greater wing of the sphenoid (GWS) bone and adjacent orbit to assist clinicians in differentiating these lesions from each other and from the most common lesion of the GWS and adjacent orbit, meningioma.

METHODS

We reviewed 32 cases of spheno-orbital lesions involving the GWS from our own practice, as well as 109 published cases (total 141), with emphasis on available imaging features on computerized tomography (CT) and MRI. Features that might assist in differentiating meningioma from its mimics were analyzed for each lesion, including the presence of an osteoblastic or hyperostotic response, bone erosion or osteolysis, homogeneous hypo- or hyperintensity on T2-weighted MRI, leptomeningeal involvement, and the absence of a "dural tail" on contrast-enhanced MRI. The clinical and imaging features were also briefly summarized for each diagnostic group.

RESULTS

The largest diagnostic group was metastasis (67 cases, 47.5%). The most useful imaging features that helped differentiate meningioma from its mimics were the presence of bone erosion and the absence of a "dural tail." Other features were helpful in a small minority of cases only. Metastatic prostate cancer was the largest single group (21 cases), and 18 (85.7%) of these were osteoblastic and most closely mimicked meningioma. Prostate cancer patients were generally older than males with GWS meningioma. Almost all other (44/46, or 95.7%) metastatic lesions showed evidence of bone erosion. Almost half (30 of 61, 49.2%) of patients with metastasis presented without a known diagnosis of malignancy. Among children 16 years of age and less, Langerhans cell histiocytosis (10 cases), dermoid cyst (5), and Ewing's sarcoma (5) were the most common diagnoses.

CONCLUSIONS

A combination of a careful history and both CT and MRI gives information, which can best guide the management of patients with spheno-orbital lesions. Metastatic prostate cancer to the GWS most closely mimics GWS meningioma but can in most cases be differentiated on clinical and imaging features. Older males with hyperostotic lesions of the GWS should be investigated for prostate cancer. Other metastatic lesions and primary tumors of the GWS, as well as benign and structural lesions can readily be differentiated from meningioma on clinical and imaging features.

Misdiagnosis and Delay of Diagnosis in Hemorrhagic Meningioma: A Case Series and Review of the Literature

OBJECTIVE

To evaluate the clinicoradiologic characteristics of hemorrhagic meningiomas (HMs) that are missed or misdiagnosed on radiologic imaging studies.

METHODS

Clinical and radiologic data from 6 patients with HM who were initially misdiagnosed were collected and recorded respectively. In addition, we performed a literature review for misdiagnosed HM and summarized the results.

RESULTS

Five of the 6 patients with misdiagnosed HM were female, and 1 was male. Both computed tomography (CT) and magnetic resonance imaging were performed in 4 patients, and CT alone was performed in 2. On CT, the HM was heterogeneously hyperdense in 5 patients and isodense in 1 patient. In all 4 patients who underwent magnetic resonance imaging, the HM was mixed iso- and hypointense on T1-weighted imaging and heterogeneously hyperintense on T2-weighted imaging. Marked heterogeneous contrast enhancement was observed in 2 patients, strong rim enhancement in 1, and peripheral enhancement in 1. The dural tail sign was seen in only 1 patient. The initial radiologic misdiagnoses were subdural hematoma (n = 1), malignant glioma (n = 1), ruptured arterial aneurysm (n = 1), metastasis (n = 2), and uncertain (n = 1). In the literature review, 22 cases of HM diagnostic error were collected. The main misdiagnoses were subdural hematoma (27.3%), traumatic hematoma (13.6%), vascular anomaly (13.6%), malignant glioma (4.5%), and metastasis (4.5%).

CONCLUSIONS

Our study showed that in patients with HM with inadequate imaging evaluation, a small tumor associated with massive hematoma and atypical imaging features was more likely to be misdiagnosed.

Marker-less augmented reality based on monocular vision for falx meningioma localization

BACKGROUND

The existing augmented reality (AR) based neuronavigation systems typically require markers and additional tracking devices for model registration, which causes excessive preparatory steps.

METHODS

For fast and accurate intraoperative navigation, this work proposes a marker-less AR system that tracks the head features with the monocular camera. After the semi-automatic initialization process, the feature points between the captured image and the pre-loaded keyframes are matched for obtaining correspondences. The camera pose is estimated by solving the Perspective-n-Point problem.

RESULTS

The localization error of AR visualization on scalp and falx meningioma is 0.417 ± 0.057 and 1.413 ± 0.282 mm, respectively. The maximum localization error is less than 2 mm. The AR system is robust to occlusions and changes in viewpoint and scale.

CONCLUSIONS

We demonstrate that the developed system can successfully display the augmented falx meningioma with enough accuracy and provide guidance for neurosurgeons to locate the tumour in brain.

Clinical Features and Prognostic Factors for Primary Anaplastic Large Cell Lymphoma of the Central Nervous System: A Systematic Review

Simple Summary

Primary anaplastic large cell lymphoma (ALCL) of the central nervous system (CNS) is a subtype of primary central nervous system lymphoma (PCNSL). ALCL is divided into anaplastic lymphoma kinase (ALK)-positive ALCL and ALK-negative ALCL, according to ALK expression. ALK-positive cancers tend to develop at a younger age and tend to have a better prognosis. Almost all past articles on primary ALCL of the CNS have been case reports and there have been no randomized trials or cohort studies on this subject. We thus performed a systematic review of primary ALCL of the CNS. According to the author’s survey, 36 case reports have been published in English-language journals. In this paper, we have summarized the clinical features and prognostic factors for primary ALCL of the CNS based on previous studies.

Abstract

Primary anaplastic large cell lymphoma (ALCL) of the central nervous system (CNS) is a subtype of primary CNS lymphoma (PCNSL). There are very few comprehensive reports on this extremely rare tumor. Therefore, it is necessary to investigate the clinical features and prognostic factors for primary ALCL of the CNS. We performed a systematic review of the published literature. Past cases were comprehensively searched using PubMed, Cochrane Library, and Web of Science. Clinical information, such as age, sex, anaplastic lymphoma kinase (ALK) status, lesion sites, treatment methods, and survivorship were extracted. Thirty-nine cases with information on ALK status and treatment course were identified. The average observation period was 13 months, and the overall 2-year survival rate was 58%. Univariate analyses showed a statistically significantly better prognosis among patients < 40 years of age (p = 0.039, HR 0.32 (0.11–0.95)) and in relation to ALK positivity (p = 0.010, HR 0.24 (0.08–0.71) and methotrexate treatment (p = 0.003, HR 0.17 (0.05–0.56)). Because of the sparsity of cases, it is necessary to accumulate cases in order to perform more detailed analyses.

Dural-based lesions: is it a meningioma?

PURPOSE

Meningiomas are the most common extra-axial intracranial neoplasms with typical radiological findings. In approximately 2% of cases, histopathological reports reveal different neoplasms or non-neoplastic lesions that can closely mimic meningiomas. We describe radiological features of meningioma mimics highlighting imaging red flags to consider a differential diagnosis.

METHODS

A total of 348 lesions with radiological diagnosis of meningiomas which underwent to surgical treatment or biopsy between December of 2000 and September of 2014 were analyzed. We determined imaging features that are not a typical finding of meningiomas, suggesting other lesions. The following imaging characteristics were evaluated on CT and MRI: (a) bone erosion; (b) hyperintensity on T2WI; (c) hypointensity on T2WI; (d) bone destruction; (e) dural tail; (f) leptomeningeal involvement; (g) pattern of contrast enhancement; (h) dural displacement sign.

RESULTS

We have a relatively high prevalence of meningioma mimics (7.2%). Dural-based lesions with homogeneous contrast enhancement (52%) are easily misdiagnosed as meningiomas. Most lesions mimic convexity (37.5%) or parafalcine (21.9%) meningiomas. We have determined five imaging red flags that can alert radiologists to consider meningioma mimics: (1) bone erosion (22.2%); (2) dural displacement sign (36%); (3) marked T2 hypointensity (32%); (4) marked T2 hyperintensity (12%); (5) absence of dural tail (48%). The most common mimic lesion in our series was hemangiopericytomas, followed by lymphomas and schwannomas.

CONCLUSION

The prevalence of meningioma mimics is not negligible. It is important to have awareness on main radiological findings suggestive of differential diagnosis due to a wide range of differentials which lead to different prognosis and treatment strategies.

Magnetic resonance imaging of the hypothalamo-pituitary region

The diagnosis and management of mass lesions in the sellar and parasellar areas remain challenging. When approaching patients with possible sellar or hypothalamic masses, it is important not only to focus on imaging but also detect possible pituitary hormone deficits or excess, in order to establish an appropriate diagnosis and initiate treatment. The imaging modalities used to characterize hypothalamic and pituitary lesions have significantly evolved over the course of the past several years. Computed tomography (CT) and CT angiography play a major role in detecting various sellar lesions, especially in patients who have contraindications to magnetic resonance imaging (MRI) and can also yield important information for surgical planning. However, MRI has become the gold standard for the detection and characterization of hypothalamic and pituitary tumors, infections, cystic, or vascular lesions. Indeed, the imaging characteristics of hypothalamic and sellar lesions can help narrow down the differential diagnosis preoperatively. In addition, MRI can help establish the relationship of mass lesions to surrounding structures. A pituitary MRI examination should be obtained if there is concern for mass effect (including visual loss, ophthalmoplegia, headache) or if there is clinical suspicion and laboratory evidence of either hypopituitarism or pituitary hormone excess. The information obtained from MRI images also provides us with assistance in planning surgery. Using intraoperative MRI can be very helpful in assessing the adequacy of tumor resection. In addition, MRI images yield reliable data that allow for noninvasive monitoring of patients postoperatively.

Imaging and diagnostic advances for intracranial meningiomas

The archetypal imaging characteristics of meningiomas are among the most stereotypic of all central nervous system (CNS) tumors. In the era of plain film and ventriculography, imaging was only performed if a mass was suspected, and their results were more suggestive than definitive. Following more than a century of technological development, we can now rely on imaging to non-invasively diagnose meningioma with great confidence and precisely delineate the locations of these tumors relative to their surrounding structures to inform treatment planning. Asymptomatic meningiomas may be identified and their growth monitored over time; moreover, imaging routinely serves as an essential tool to survey tumor burden at various stages during the course of treatment, thereby providing guidance on their effectiveness or the need for further intervention. Modern radiological techniques are expanding the power of imaging from tumor detection and monitoring to include extraction of biologic information from advanced analysis of radiological parameters. These contemporary approaches have led to promising attempts to predict tumor grade and, in turn, contribute prognostic data. In this supplement article, we review important current and future aspects of imaging in the diagnosis and management of meningioma, including conventional and advanced imaging techniques using CT, MRI, and nuclear medicine.

Identification of a Transcription Factor-microRNA-Gene Coregulation Network in Meningioma through a Bioinformatic Analysis

Background

Meningioma is a prevalent type of brain tumor. However, the initiation and progression mechanisms involved in the meningioma are mostly unknown. This study aimed at exploring the potential transcription factors/micro(mi)RNAs/genes and biological pathways associated with meningioma.

Methods

mRNA expressions from GSE88720, GSE43290, and GSE54934 datasets, containing data from 83 meningioma samples and eight control samples, along with miRNA expression dataset GSE88721, which had 14 meningioma samples and one control sample, were integrated analyzed. The bioinformatics approaches were used for identifying differentially expressed genes and miRNAs, as well as predicting transcription factor targets related to the differentially expressed genes. The approaches were also used for gene ontology term analysis and biological pathway enrichment analysis, construction, and analysis of protein-protein interaction network, and transcription factor-miRNA-gene coregulation network construction.

Results

Fifty-six upregulated and 179 downregulated genes were identified. Thirty transcription factors able to target the differentially expressed genes were predicted and selected based on public databases. One hundred seventeen overlapping genes were identified from the differentially expressed genes and the miRNAs predicted by miRWalk. Furthermore, NF-κB/IL6, PTGS2, MYC/hsa-miR-574-5p, hsa-miR-26b-5p, hsa-miR-335-5p, and hsa-miR-98-5p, which are involved in the transcription factor-miRNA-mRNA coregulation network, were found to be associated with meningioma.

Conclusion

The bioinformatics analysis identified several potential molecules and relevant pathways that may represent critical mechanisms involved in the progression and development of meningioma. This work provides new insights into meningioma pathogenesis and treatments.

Increased Risk of Subsequent Meningioma Among Women with Malignant Breast Cancer

OBJECTIVE

Despite the increasing evidence of the association between breast cancer and meningioma in women, the relationship between these tumors remains improperly examined. In this study, we aim to identify the sociodemographic and clinicopathologic features of women with breast cancer associated with a higher risk of developing a meningioma.

METHODS

The SEER (Surveillance Epidemiology and End Results) database (18 registries) was used to identify women with breast cancer as their first neoplasm. The risk of subsequent meningioma was reported as the standardized incidence ratio (SIR) and was analyzed by sociodemographic and clinicopathologic subgroups. Results are given as SIR (95% confidence interval [CI]).

RESULTS

A total of 564,516 women diagnosed with breast cancer between 2004 and 2016 were included for analysis. A 26% increased risk of meningioma development (SIR, 1.26; 95% CI, 1.19-1.33; P < 0.05) was found in the cohort compared with the general population. Patients aged between 18 and 49 years (SIR, 2.16; 95% CI, 1.78-2.61; P < 0.05) and those with a more advanced tumor stage (stage IV; SIR, 2.39; 95% CI, 1.71-3.25; P < 0.05) were at a higher risk. Hormone receptor expression and treatment modality subgroups were at a similar risk compared with the general population.

CONCLUSIONS

Our study corroborated the known association between these tumors and found a 26% risk of meningioma development in women with breast cancer, with younger patients and those with a more aggressive disease having a higher than expected risk.

Metastatic Renal Cell Carcinoma Masquerading as a Sphenoid Wing Meningioma

A 47-year-old man who presented with subacute binocular diplopia and a left head turn was found to have a right sixth nerve palsy and right optic disc edema. Radiologic imaging revealed a non-lytic right greater sphenoid wing mass with a dural tail, suggestive of a sphenoid wing meningioma. The patient underwent an orbitotomy with lesion biopsy; histopathologic analysis and subsequent imaging revealed the diagnosis of metastatic clear cell renal cell carcinoma. He developed new metastases despite systemic immunotherapy, and prognosis was guarded at last follow up 3 months after diagnosis. The authors present the first reported case of renal cell carcinoma metastatic to the sphenoid wing without sinus involvement, describing an atypical presentation of an aggressive malignancy that necessitates timely diagnosis for possible survival.

Small Cell Variant of Anaplastic Lymphoma Kinase-Positive Anaplastic Large Cell Lymphoma of the Dura Mimicking Tentorial Meningioma

BACKGROUND

Primary central nervous system (CNS) anaplastic large cell lymphoma (ALCL) is an uncommon type of brain tumor, usually treated with a regimen that includes high-dose methotrexate (MTX). Only a few cases of primary CNS anaplastic lymphoma kinase (ALK)-positive ALCL have been reported so far, with no reported cases of a small cell variant.

CASE DESCRIPTION

A 26-year-old man presenting with headache and visual field impairment was found to have a supratentorial mass mimicking meningioma. Craniotomy was performed for tumor resection, and postoperative histologic examination revealed atypical cells that were nonenlarged lymphocytes with irregularly shaped and enlarged nuclei; these cells were cluster of differentiation 30 and ALK-positive, leading to the diagnosis of a small cell variant of ALK-positive ALCL. In this case, the tumor exhibited an aggressive behavior with MTX resistance with metastases in the pelvis but responded well to cytarabine and etoposide (CYVE).

CONCLUSIONS

In general, CNS ALK-positive ALCL responds well to MTX, but small cell variants show aggressive behavior and may be resistant to MTX. For small cell variants of ALCL that are resistant to MTX therapy, as in this case, CYVE therapy may be an effective treatment.

Radiomic Analysis of Craniopharyngioma and Meningioma in the Sellar/Parasellar Area with MR Images Features and Texture Features: A Feasible Study

Purpose

To investigate the ability of qualitative Magnetic Resonance (MR) images features and quantitative Magnetic Resonance Imaging (MRI) texture features in the contrastive analysis between craniopharyngioma and meningioma.

Method

A total number of 127 patients were included in this study (craniopharyngioma = 63; meningioma = 64). All the features analyzed in this study were acquired from preoperative MRI images. Qualitative MR images features were evaluated with chi-square tests or Fisher exact test, while MRI texture features were evaluated with the Mann-Whitney U test with the Benjamini-Hochberg method. Then binary logistic regression analysis for texture features was performed to evaluate their ability as independent predictors, and the diagnostic accuracy was calculated next for these texture features with high abilities as independent predictors using receiver operating characteristic (ROC) curves.

Results

Four qualitative MR images features showed significant difference between craniopharyngioma and meningioma, but only cystic alteration could be considered as diagnostic independent predictors. Meanwhile, three quantitative parameters, histogram-based matrix- (HISTO-) Skewness, Grey-level co-occurrence matrix- (GLCM-) Contrast on contrast-enhanced images, and HISTO-Skewness on images of T2-weighted imaging (T2WI), showed promising abilities in the contrastive analysis. Besides, these texture features were found significantly to be relative to cystic alteration.

Conclusion

MR images features and texture features were useful in the contrastive analysis of craniopharyngioma and meningioma. Furthermore, qualitative MR images features and MRI texture features could be related to each other.

Secondary Diffuse Large B-cell Lymphoma Mimicking Meningioma

Meningiomas are the most common benign intracranial tumors accounting for up to 30% of non-glial tumors of the central nervous system (CNS); on neuroimaging studies, they usually appear as a lobular, extra-axial mass with well-circumscribed margins mostly located in the parasagittal aspect of the cerebral convexity. On magnetic resonance imaging (MRI) of the brain, meningiomas are typically isointense to hypointense relative to grey matter in the T1-weighted sequence and isointense to slight hyperintense relative to grey matter on the T2-weighted sequence with avid homogeneous enhancement after contrast administration. A thin linear enhancement along the dura infiltrating away from the lesion, known as the dural tail sign, was once thought to be a pathognomonic feature of meningiomas, but this non-specific sign can also be seen in other meningioma-like lesions. Several benign and malignant pathologies may mimic some of the neuroimaging characteristics of meningiomas; among them dural metastases of lymphomas. When approaching a patient with suspected meningioma, close attention to the neuroimaging features may help distinguish them from meningioma-like lesions. Here we present the case of a woman with CNS involvement of non-Hodgkin lymphoma that presented with a dural mass resembling the neuroimaging characteristics of a meningioma. 

Dynamic contrast-enhanced magnetic resonance imaging perfusion characteristics in meningiomas treated with resection and adjuvant radiosurgery

OBJECTIVE

There is a need for advanced imaging biomarkers to improve radiation treatment planning and response assessment. T1-weighted dynamic contrast-enhanced perfusion MRI (DCE MRI) allows quantitative assessment of tissue perfusion and blood-brain barrier dysfunction and has entered clinical practice in the management of primary and secondary brain neoplasms. The authors sought to retrospectively investigate DCE MRI parameters in meningiomas treated with resection and adjuvant radiation therapy using volumetric segmentation.

METHODS

A retrospective review of more than 300 patients with meningiomas resected between January 2015 and December 2018 identified 14 eligible patients with 18 meningiomas who underwent resection and adjuvant radiotherapy. Patients were excluded if they did not undergo adjuvant radiation therapy or DCE MRI. Demographic and clinical characteristics were obtained and compared to DCE perfusion metrics, including mean plasma volume (vp), extracellular volume (ve), volume transfer constant (Ktrans), rate constant (kep), and wash-in rate of contrast into the tissue, which were derived from volumetric analysis of the enhancing volumes of interest.

RESULTS

The mean patient age was 64 years (range 49–86 years), and 50% of patients (7/14) were female. The average tumor volume was 8.07 cm3 (range 0.21–27.89 cm3). The median Ki-67 in the cohort was 15%. When stratified by median Ki-67, patients with Ki-67 greater than 15% had lower median vp (0.02 vs 0.10, p = 0.002), and lower median wash-in rate (1.27 vs 4.08 sec−1, p = 0.04) than patients with Ki-67 of 15% or below. Logistic regression analysis demonstrated a statistically significant, moderate positive correlation between ve and time to progression (r = 0.49, p < 0.05). Furthermore, there was a moderate positive correlation between Ktrans and time to progression, which approached, but did not reach, statistical significance (r = 0.48, p = 0.05).

CONCLUSIONS

This study demonstrates a potential role for DCE MRI in the preoperative characterization and stratification of meningiomas, laying the foundation for future prospective studies incorporating DCE as a biomarker in meningioma diagnosis and treatment planning.

Subdural haematoma mimics

A subdural haematoma (SDH) is a frequently encountered pathology seen on an emergency room computed tomography (CT) head scan. An extra-axial crescentic density along the convexity of the brain or within the interhemispheric fissure is generally thought to represent a SDH; however, SDH mimics are known to occur in nature, and can be broadly classified under the subcategories of normal anatomy, artefacts, tumour, inflammation, infection, ischaemia, trauma, and iatrogenic. Understanding the typical characteristics of a SDH, knowledge of normal anatomy, close inspection of the morphology of the subdural process, changes to the adjacent structures, and rigorous attention to clinical details may reveal subtle clues that distinguish a true SDH from a mimic. This is crucial in appropriately directing clinical management. This review amalgamates most of the rare subdural processes that have been reported to mimic SDH, and discusses the imaging and clinical features that help to differentiate between them. This topic is highly valuable for radiology trainees, general radiologists, and emergency room physicians, and may serve as a refresher for the practising neuroradiologist.

Prevalence of hitherto unknown brain meningioma detected on 68Ga-DOTATATE positron-emission tomography/computed tomography in patients with metastatic neuroendocrine tumor and exploring potential of 177Lu-DOTATATE peptide receptor radionuclide therapy as single-shot treatment approach targeting both tumors

There is a relative paucity of data in the literature regarding the prevalence of meningiomas and their detection in the clinical setting of neuroendocrine tumors (NETs). The primary aim of this study was to study incidentally detected meningiomas (on ⁶⁸Ga-DOTATATE/ ¹⁸F fluorodeoxyglucose positron-emission tomography/computed tomography [¹⁸F-FDG PET/CT]) in metastatic NET patients referred for peptide receptor radionuclide therapy (PRRT). The secondary aims of this study were to evaluate the response rate of these incidentally detected meningiomas following PRRT and determine progression-free survival (PFS) in this group of patients. This was a retrospective analysis of 500 metastatic/advanced NET patients who had undergone ⁶⁸Ga-DOTATATE PET/CT and ¹⁸F-FDG PET/CT before PRRT workup. The case records were searched to identify cases of hitherto unknown meningiomas detected on PET images; subsequently, these patients underwent brain magnetic resonance imaging (MRI) for confirmation of diagnosis. Following ¹⁷⁷Lu-DOTATATE PRRT, posttreatment functional and structural imaging response evaluation of the meningiomas were undertaken by ⁶⁸Ga-DOTATATE PET/CT, MRI, or CT brain, respectively, along with clinical neurological evaluation. The patients were designated as responders and nonresponders based on predefined response assessment criteria. The PFS of these incidentally detected meningiomas following PRRT was estimated using the Kaplan-Meier product-limit method. Twelve NET patients were retrospectively identified with abnormal focal brain uptake on ⁶⁸Ga-DOTATATE PET/CT. Of these, meningiomas were finally diagnosed on brain MRI examination in six patients (M: F =3:3; age range: 30-66 years; and mean age: 45 years), with a prevalence of 1.2%. Standardized uptake value (SUVmax) of meningiomas on ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT ranged from 7.0 to 22.0 (average 17.0) and 10.19-13.70 (mean: 12.10), respectively, and lesion-to-normal brain parenchyma SUVmax ratio ranged from 140 to 400 (mean: 340) and 1.02-1.07 (mean: 1.04), respectively. Of six patients with incidentally detected meningiomas, one patient died within 1 month and five patients received ¹⁷⁷Lu-DOTATATE PRRT, the number of cycles ranging from two to six (average: 4) and cumulative therapeutic dose ranging from 13.28 to 29.97GBq (average dose: 19.86GBq). Follow-up in these patients ranged from 8 to 36 months (mean: 19.4 months) after the first dose of PRRT. Complete disappearance of neurological symptoms was found in two of five patients (40%), partial response in one of five (20%), and worsening of symptoms in two of five patients (40%). The overall "responder" and "nonresponder" of the meningiomas after PRRT were three patients (60%) and two patients (40%), respectively. Two patients (40%) died of advanced NET at the time of analysis of these data. The observed mean PFS of the meningioma lesions following PRRT was 26.25 months (95% confidence interval, 16.65-35.84 months). No major hematological and renal toxicity were documented in any of these patients. To conclude, ⁶⁸Ga-DOTATATE PET/CT imaging is an effective technique for the incidental identification of meningioma in NET patients. Considering the limited therapeutic options in the palliative setting of advanced or metastatic NET patients and morbidity associated with the therapeutic procedures, PRRT could be a promising targeted therapeutic approach for such cases of incidentally detected meningiomas, which is also helpful in stabilizing the disease process without any significant toxicity.

Dural-Based Cavernous Malformation at the Cerebral Convexity: Report of Two Pediatric Patients

BACKGROUND

Intracranial cavernous malformations (CMs) are usually located at the cerebral parenchyma; dural-based CMs outside the middle fossa are rarely reported. To our knowledge, dural-based CMs located at the cerebral convexity are even rarer in that only 2 pediatric cases have ever been reported. In this report, we present 2 extremely rare cases of dural-based CMs at the cerebral convexity in pediatric patients. The clinical course, radiologic and pathologic features, treatment, and follow-up are described.

CASE DESCRIPTION

The first case is a 6-year-old boy who presented with headache and vomiting and was found to have an acute subdural hematoma and space-occupying lesion. Intraoperative findings and histologic examination were consistent with a CM. He experienced an uneventful postoperative recovery. The second case is a 43-day-old female neonate who presented with a progressively enlarging neoplasm at the right occipital region since birth. Computed tomography of the head performed at admission showed a slight hyperdense occupying lesion communicating between the intra- and extracranial cavity through a skull defect. The lesion was resected en bloc and histologic examination was in accord with a CM.

CONCLUSIONS

The clinical manifestations and radiologic characteristics of dural-based CMs are nonspecific. Unlike that of their cerebral parenchymal counterparts, the radiologic appearance of dural-based CMs is confusing and misleading. Surgical resection is the primary treatment selection for dural-based CMs. In cases with no close relationship to dural sinuses, complete surgical resection with minimal blood loss and few neurologic deficits could be easily achieved.