Meningioangiomatosis with Variable Imaging Feature: Rare Cause of Drug Refractory Epilepsy

Abstract

Meningioangiomatosis is a rare entity, commonly affecting leptomeninges and the cerebral cortex. It presents in the second decade of life with drug-resistant epilepsy. Meningioangiomatosis lacks a typical computed tomography or magnetic resonance imaging appearance, making the presurgical diagnosis a challenge. Diagnosis often depends on recognizing gyriform cortical patterns with or without calcification. This report presents two biopsy-proven cases of meningioangiomatosis with entirely different imaging features. Postsurgical excision carries a favorable prognosis.

Keywords

meningioangiomatosis - leptomeninges - calcification

Introduction

Meningioangiomatosis (MA) is an uncommon localized hamartomatous or meningiovascular proliferative lesion found in the meninges and the underlying cerebral cortex, mainly in the frontal and temporal lobes.[1] This condition is primarily characterized as unifocal and sporadic but has also been described in association with meningioma and neurofibromatosis (NF).[1] Pathologically, it is characterized by the proliferation of blood vessels within the leptomeninges and the cortex. Meningothelial and fibroblastic cells are observed to spread around the Virchow–Robin (VR) spaces of small leptomeningeal and intracortical blood vessels.[1] [2] [3] [4] It typically occurs in children and young adults who present with partial seizures, drug-resistant epilepsy, and headaches[5] and it is a diagnosis that needs to be considered in people with drug-refractory seizures. Radiologically, it has a variable appearance. On noncontrast computed tomography (NCCT), predominantly hypodensities have been described with calcification up to 90% of cases.[6] Magnetic resonance imaging (MRI) is the modality of choice and reveals T1 iso- to hypointense signal with T2/fluid-attenuated inversion recovery (FLAIR) gyriform hyperintensities, and cystic degenerations with variable contrast enhancement.[6] [7] Cerebral angiogram is normal in most cases with occasional abnormal vessels.[8] Due to its variable imaging appearance, radiologists face challenges in differentiating MA from ganglioglioma, cavernoma, dysembryoplastic neuroepithelial tumor (DNET), and calcifying pseudoneoplasms of the neuraxis. Preoperative diagnosis of MA is helpful in prognosis due to its benign nature without malignant potential.[9]

In this article, we present two cases with diverse imaging findings. One case featured a completely calcified lesion, while the other had a noncalcified cortical–subcortical lesion with cystic changes. Both cases showed a positive response following surgical resection.

Case Presentation

Case 1

A 19-year-old boy presented in the neurology outpatient department (OPD) with a history of left focal motor seizures since the age of 10 years. Family history was negative for seizure and the perinatal period was uneventful. Seizure frequency was twice a week. Upon examination, he was alert and without neurological deficits. Video electroencephalogram (VEEG) localization indicated abnormal activity in the right frontoparietal lobe. Initially, he was managed conservatively but later on changing medication for controlling seizures. NCCT brain ([Fig. 1A]) revealed thickening of the cortex with subcortical hypodensity in the right anterior frontal lobe's middle frontal gyri. A 3T MRI brain showed an area of disorganized gyral pattern with T2/FLAIR gyral and sulcal ([Fig. 1C–E]) hyperintensities and prominent Virchow spaces in the cortical and subcortical regions of the right middle frontal gyri. No contrast enhancement was observed ([Fig. 1G]). The lesion remained stable in size during follow-up imaging. Based on the imaging findings, a provisional diagnosis of DNET or MA was considered. The patient subsequently underwent a right frontal craniotomy and gross total resection under electrocorticography (ECOG) guidance. The lesion was pale yellow, firm to hard in consistency, and highly vascular with an area of calcifications. Piecemeal dissection with excision was done; medially excised till falx, posteriorly till premotor cortex, laterally till inferior frontal gyrus, and inferiorly till cingulate gyrus. Histopathological examination ([Fig. 2]) showed proliferation of meningothelial cells around blood vessels with a positive marker (epithelial membrane antigen and somatostatin receptor 2A [SSTR2A]) confirming the diagnosis of MA. After 6 months of surgery, the patient has been on continuous follow-up and is now seizure-free.

Fig. 1 Meningioangiomatosis in a 19-year old. Noncontrast CT brain axial section (A) revealed thickening of the right middle frontal cortex (arrow) with subcortical hypodensity. 3T magnetic resonance imaging (MRI) brain axial T1-weighted (T1W) (B) image shows a disorganized gyral pattern with the hypointense subcortical region (arrow). The lesion shows prominent subcortical linear hyperintensity (Virchow space) in axial T2W (C) images, which were suppressed on fluid-attenuated inversion recovery (FLAIR) (D and E). The lesion did not show diffusion restriction (F) and contrast enhancement as depicted on axial T1FS + C (G). Postop changes with cavity shown in noncontrast computed tomography (NCCT) axial image (H).

Fig. 2 Histopathological examination: (A) hematoxylin and eosin (H&E) (10 × ) shows proliferation of meningothelial cells (arrow) around blood vessels in a fibrillary background; (B) H&E (40 × ) shows the similar finding of meningothelial proliferation (arrow) around blood vessels; (C) immunohistochemistry (10 × ) for epithelial membrane antigen (EMA) is positive, and also (D) immunohistochemistry for somatostatin receptor 2A (SSTR2A) is positive confirming the meningothelial cells. Diagnosis of meningioangiomatosis was made.

Case 2

A 30-year-old female presented at the neurology OPD with a long history of drug-resistant focal seizures, occurring since the age of 10 years. VEEG localization indicated abnormal activity in the left front-temporal region. NCCT brain revealed a subcortical calcified lesion with a gyral pattern of calcification in the left parietal lobe medially ([Fig. 3A]). A 3T MRI brain scan revealed a well-defined ovoid hypointense lesion in the left parietal lobe, which appeared hypointense on both T1- and T2-weighted images ([Fig. 3B, C]). There was no evidence of contrast enhancement ([Fig. 3D]), or no surrounding FLAIR hyperintensity, or gliosis. The initial differential diagnosis included MA or polymorphous low-grade neuroepithelial tumor of the young. Another incidental small calcified lesion on NCCT ([Fig. 3F]) with T2 hypointense center ([Fig. 3G]) and rim enhancement on T1 fat-saturated contrast ([Fig. 3H]) with surrounding gliosis on FLAIR ([Fig. 3I]), was noted in the right precentral gyri in the frontal lobe likely of neurocysticercosis. As the VEEG localization indicated activity on the left side, surgery was planned to excise the lesion located in the left parietal lobe. ECOG recording showed abnormal activity over the medial cortex. Left parietal craniotomy with an interhemispheric approach was used for surgery under ECOG guidance. The lesion was well-defined, firm calcified in the left medial parietal subcortical region and excised in toto. Histopathological examination ([Fig. 4]) showed proliferation of meningothelial cells around blood vessels with a positive marker (SSTR2A and SSTR5) confirming the diagnosis of MA. Follow-up MRI of brain axial T2 done after 5 months of surgery ([Fig. 3E]) showed no residual lesion and the patient was seizure-free.

Fig. 3 Calcified meningioangiomatosis (MA) in a 30-year-old female with drug-refractory seizures. Noncontrast computed tomography (NCCT) brain axial image (A) shows well-defined calcified lesion (arrow) with a gyral pattern of calcification in the left parietal lobe medial subcortical region. The lesion appears hypointense on T2-weighted (T2W) (B), and T1W (C) with no postcontrast enhancement on axial T1 FS + C image (D). Postop magnetic resonance imaging (MRI) after 5 months, axial T2W image (E) reveals no residual lesion with a postop cavity (arrow). Another focus of calcification on NCCT (F) was noted in the right premotor cortex with surrounding fluid-attenuated inversion recovery (FLAIR) hyperintensity (I). The lesion shows a hypointense center on axial T2W (G) with mild rim enhancement (arrow) on postcontrast axial T1FS + C image (H) s/o neurocysticercosis (NCC).

Fig. 4 Histological examination of sample received from left parietal lobe lesion. (A) hematoxylin and eosin (H&E) (10 × ) shows meningothelial cell proliferation around blood vessels; (B) H&E (40 × ) on higher power of the similar finding showing proliferation of meningothelial cells around blood vessels. Immunohistochemistry (40 × ) for (C) somatostatin receptor 2A (SSTR2A) and (D) somatostatin receptor 5 (SSTR5) both are positive. Diagnosis of meningioangiomatosis was made.

Discussion

The exact pathophysiology of MA remains unclear. Several hypotheses have been proposed, including developmental and hamartomatous (MA and NF),[10] dysplastic (proliferation of meningothelial cells),[11] or reactive origins (MA and meningiomas).[1] [11] In a study conducted by Wiebe et al,[2] MA was found sporadically in 75% of patients and was associated with NF in 25% of cases.

Seizure was the only symptom in 42 patients (85%).[2] The mean age of diagnosis in sporadic cases was 28 years[2] and one of our cases was also 30 years old. Sporadic cases are usually symptomatic and have solitary lesions, whereas the MA with NF2 ones are often asymptomatic, and multiple lesions with MA are detected as an incidental finding.[7] Similarly to the study by Sun et al,[7] both cases were symptomatic with drug-refractory epilepsy and had solitary lesions.

Imaging findings of MA are variable in both CT as well as MRI.[9] NCCT shows calcification in 89.6%[6] cases. One of our cases was entirely calcified with another having a hypodense area. A calcified lesion with surrounding hypodensity was noted in 55% of cases in a study by Wiebe et al.[2]

Both of our cases were confined to the cortex[12] and 90% of MA involves the cortex.[2] MA cases commonly show gyral hyperintensity and prominent VR spaces due to meningothelial cell spread.[13]

Both cases did not show any contrast enhancement as opposed to 80% of cases demonstrating some degree of enhancement in a study done by Kashlan et al[6] and Bulut et al.[14] Differential diagnosis is broad due to variable imaging features. It includes meningioma, oligodendroglioma, calcifying pseudoneoplasm of the neuraxis, cavernous malformation, ganglioglioma for case no. 2, and low-grade astrocytoma and DNET for case no. 1.[12] [13]

Compared with MA, gliomas typically exhibit a surrounding hyperintense FLAIR signal, which was absent in our case. Meningiomas are usually dural-based, while MA is primarily cortical. Cavernous malformations can be differentiated by their multiloculated appearance and a hypointense rim on T2-weighted images. DNET have a peripheral hyperintense FLAIR rim and a bubbly appearance on T2-weighted, whereas our case demonstrates prominent VR spaces, which is typically found in MA.[12] Surgical resection is the main treatment modality and has a good prognosis. Both cases were seizure-free after surgery. In literature, seizure-free rates can be seen in up to 63% of cases, and improvement in seizures was noted in 30% of cases.[2]

Conclusion

In conclusion, we have presented two cases of drug-resistant epilepsy in young individuals with biopsy-proven MA. Both cases exhibited diverse imaging features. Following surgical excision, both patients experienced significant improvements in their symptoms. Given its benign nature, the prognosis for MA appears favorable when compared with other similar tumors.

Conflict of Interest

None declared.

Authors' Contributions

B.D.C., V.G., S.D., S.A., A.G., L.J.D.S., S.J., S.A.H., and A.S. contributed to the acquisition, analysis, conception, design, and drafting of the work. B.D.C. and V.G., along with R.B. and A.G. contributed to the final draft, revisions, upload, and submission of the final revised work. All authors have agreed both to be personally accountable for their contributions and ensured that questions related to the accuracy or integrity of any part of the work, even ones in which one was not personally involved, are appropriately investigated, resolved, and the resolution documented in the literature. All authors have read and approved the manuscript.

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Publikationsverlauf

Artikel online veröffentlicht:
10. Januar 2025