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Neuroradiology Case of the Week

Case 266

Virendra Kumar, MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: Patient with transient visual obscuration and history of hypertension being evaluated for Ischemia.

Imaging Findings: A large, 26 x 20 x16 mm , well-defined, intraparenchymal cystic lesion, paralleling CSF is seen on T1W, T2W and FLAIR sequence. There is no evidence of internal echos. A small septa is seen. There is no perilesional edema, no mass effect, and no nodule. No enhancement is seen on the post-contrast images. The rest of the brain parenchyma is normal. No other parenchymal lesion is seen.

Diagnosis: Neuroglial cyst

Discussion: Neuroglial (also called glioependymal) cysts are benign epithelial-lined lesions that occur anywhere in the neuraxis.They are uncommon, representing fewer than 1% of intracranial cysts . While they may occur in myriad locations, the frontal lobe is the most typical location. Also, intraparenchymal neuroglial cysts are more common than extraparenchymal cysts.
     Intraparenchymal neuroglial cysts are congenital lesions, arising from embryonic neural tube elements that become sequestered within the developing white matter. They are rounded, smooth, and unilocular and contain clear fluid that resembles CSF. They are lined by ependymal (columnar epithelium) or choroid plexus cells (low cuboidal epithelium)

Imaging: The best diagnostic clue to a neuroglial cyst is a nonenhancing CSF-like parenchymal cyst with minimal to no surrounding signal intensity abnormality. The cysts are benign-appearing lesions with smooth, rounded borders . Size is variable.

Presentation: Most commonly present with headache.

Demographics: They may present at any age, however usually in adults rather than children. No gender predilection.

Differential Diagnosis: Other lesions that may be mistaken for a neuroglial cyst include
     1.  an enlarged PVS
     2.  infectious cyst
     3.  porencephalic cyst
     4.  arachnoid cyst
Enlarged PVSs are typically multiple and cluster around the basal ganglia. Infectious cysts, such as neurocysticercosis, are typically smaller than 1 cm and can partially enhance. Porencephalic cysts communicate with the lateral ventricle and show surrounding gliosis. Arachnoid cysts are typically extraaxial.

Treatment: Mainly kept under observation and if there are symptomatic fenestration vs drainage of cyst may be performed.

References:

1. Tsuchida T, Kawamoto K, Sakai N, Tsutsumi A. Glioependymal cyst in the posterior fossa. Clin Neuropathol. 1997 Jan-Feb;16(1):13-6. [Medline]
2. Osborn AG. Neuroglial cyst. In: Diagnostic Imaging: Brain. Salt Lake City, Utah: Amirsys, 2004; I-7-20.
3. Osborn AG. Miscellaneous tumors, cysts, and metastases. In: Diagnostic Neuroradiology. St Louis, Mo: Mosby, 1994; 631–649.