CASE 14267 Published on 27.11.2016

Cystic meningioma in an adult

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Aikaterini Solomou, Pantelis Kraniotis

University Hospital Patras,Department of Radiology,Magnetic Resonance Imaging Unit ; Rion 26504 Rion, Greece; Email:solomou@med.upatras.gr
Patient

62 years, female

Categories
Area of Interest Neuroradiology brain ; Imaging Technique MR
Clinical History
The patient presented with sudden onset of seizures and loss of conscience.
Imaging Findings
The patient was submitted to brain MRI with T1WI, FLAIR, SWI, DWI, as well as T1WI post IV Gadolinium (Gad) administration in the axial, sagittal and coronal planes(figures 1-5). The MRI revealed an extra-axial, dural based lesion in the left parietal lobe measuring 3.5x3.4x3.2 cm. The lesion had a solid enhancing central part, with multiple well-circumscribed peripheral cysts (ddx:concommitant CSF clefts). There was no vasogenic edema, or midline shift. There was mild buckling of the white matter. The adjacent dura was thickened and enhanced. On DWI, the lesion showed slight diffusion restriction of the solid component. The cystic areas followed the CSF signal on all sequences. There was no evidence of hemosiderin/calcification on SWI. The findings were compatible with cystic meningioma, type 4. The tumour was surgically resected. Histopathology confirmed the diagnosis of cystic meningioma, grade I WHO.
Discussion
Meningiomas are the most common extra-axial neoplasms, representing 15% of all intracranial tumours [1]. Most meningiomas are benign, however atypical and malignant meningiomas may also exist.
Cystic meningiomas are rare in adults, accounting for only 2-4% of meningiomas and are, on the other hand, more frequent (10-19%) in infants and children [2]. The aetiology of meningioma is unclear. However, known risk factors comprise radiation exposure and type II neurofibromatosis.
The majority of meningiomas are located in the frontal, parietal lobes, arising from the falx or the convexity meninges [3].
According to the Nauta classification [4], cystic meningiomas are divided into four types: I-with a central cyst; II-with a peripheral intratumoral cyst; III-cyst wall may comprise a nest of tumor cells; IV-with a peritumoral cyst, located between the meningioma and brain.
Worthington [5] added a supplementary type V, where the cysts enclose the tumour nodule, with neoplastic cells on the cystic wall. Weber [6] subdivided the peritumoral cystic meningioma according to the presence of tumour invasion in the cystic wall.
The exact mechanism of cyst formation is unknown. Types I and II are probably the result of microcystic degeneration, intratumoral haemorrhage or ischemic necrosis. Type III may be due to reactive gliosis or cerebral oedema, type IV may be the result of widened subarachnoid spaces and trapped cerebrospinal fluid around the tumour [3].
Meningiomas may be asymptomatic or present with headaches, seizures or focal neurologic deficit.
MRI is the modality of choice for diagnosing cystic meningioma, with higher accuracy than CT, however only histolopathology can lead to the accurate diagnosis [7]. Combined MRI and DWI may be helpful in the diagnosis of the type of cystic meningioma [8]. The cystic parts are hypointense or mildly hyperintense on DWI, whereas the ADC values are increased.
Typical MR findings include an extra-axial tumour with a broad dural base. The solid part shows intense enhancement, while the associated cysts may illustrate wall enhancement, in spite of the absence of tumour cells [9]. The absence of Gad-enhancement of the cystic component does not exclude the presence of tumour cells [10]. Regarding the dural tail sign, it may also be observed in glioblastoma, parenchymal/dural metastases and schwannomas. Peritumoral oedema, presenting in 60% of meningiomas, may incorrectly suggest an intra-axial lesion, i.e. glioma.
Treatment is surgical if the lesion is symptomatic. If asymptomatic, follow-up is recommended. If malignant cells are found on histopathology, radiation therapy may also be used.
Differential Diagnosis List
Cystic meningioma, type IV.
dural metastasis
primary intra-axial glial neoplasm
Final Diagnosis
Cystic meningioma, type IV.
Case information
URL: https://www.eurorad.org/case/14267
DOI: 10.1594/EURORAD/CASE.14267
ISSN: 1563-4086
License