6 Choroid Fissure Cyst


6 Choroid Fissure Cyst

Susana Calle, Pejman Rabiei, Shekhar D. Khanpara, and Roy F. Riascos

6.1 Case Presentation

6.1.1 History and Physical Examination

A 5-year-old girl with a 1-year history of occasional mild occipital headache admitted to the ER (emergency room) because of a facial laceration from a fall.

The patient had a small facial laceration but was otherwise normal with no neurological deficits.

6.1.2 Imaging Findings and Impression

Axial (▶ Fig. 6.1a) and coronal (▶ Fig. 6.1b) CT scans of the head without contrast demonstrate a well-circumscribed cerebrospinal fluid (CSF) density lesion (white arrows) measuring approximately 10 × 10 mm in the choroidal fissure. The lesion has an imperceptible wall with no evidence of a solid component within the cyst.

Fig. 6.1 (a–h)

However, MR was performed to exclude the less likely possibility of a small cystic lesion. The cyst follows CSF signal intensity on axial T1-weighted (black arrow on ▶ Fig. 6.1c), axial fluid-attenuated inversion recovery (FLAIR; ▶ Fig. 6.1d), and coronal high-resolution fast spin-echo (FSE) T2-weighted (▶ Fig. 6.1e) images (white arrows). Coronal image (▶ Fig. 6.1e) clearly shows that the 10-mm cyst lies within the choroidal fissure. The distinctive spindle shape of the lesion is best seen in the T1-weighted sagittal plane (asterisk on ▶ Fig. 6.1f). The lesion does not show restriction on diffusion-weighted and ADC (apparent diffusion coefficient) map images (arrows on ▶ Fig. 6.1g,h).

6.2 Differential Diagnosis

  • Choroid fissure cysts:

    • Choroid fissure cysts are a normal variant occurring in the choroidal fissure and follow the CSF signal intensity on all sequences, with the absence of nodular enhancement.

  • Mesial temporal sclerosis:

    • This is rarely an incidental finding but rather a common cause of epilepsy.

    • The hippocampus (uni- or bilateral) is atrophic with abnormal signal intensity on FLAIR images and with loss of normal internal architecture on T2-weighted images.

    • The ipsilateral fornix is also often noted to be small.

    • This atrophy may result in ipsilateral widening of the temporal horn and choroidal fissure.

    • The primary abnormality of the hippocampus and secondary widening of adjacent CSF spaces should distinguish this from a choroid fissure cyst in which the adjacent brain is displaced due to mass effect but is otherwise normal. 1

  • Epidermoid cysts:

    • They are more commonly found in the CPA (cerebellopontine angle) cistern.

    • Epidermoid cysts do not suppress on FLAIR images completely and are bright on diffusion-weighted images, unlike choroid fissure cysts.

  • Parasitic cysts (neurocysticercosis):

    • They are more common in tropical countries.

    • Typically, they are parenchymal but can be present in the subarachnoid space.

    • The vesicular stage of neurocysticercosis (tapeworm infection) can look similar, but the cysts are most often multiple.

    • Nonenhancing T2 hypointense/T1 hyperintense scolex can be identified within the cysts.

    • They evolve into colloidal vesicular, granular nodular, and nodular calcified stages over time.

  • Hippocampal sulcus remnants:

    • They are multiple tiny cysts within the hippocampus itself and are therefore seen just medial to the temporal horn of the lateral ventricle but between the dentate gyrus and subiculum.

    • They are incidental findings and follow the CSF signal intensity on all sequences.

  • DNETs (dysembryoplastic neuroepithelial tumors):

    • Intra-axial mass/masslike abnormalities as opposed to a choroid fissure cyst that may compress adjacent brain but is extra-axial in location.

    • They often occur in the temporal lobes and have a pseudocystic/bubbly appearance.

    • They do not suppress on FLAIR sequences and often have a bright rim, which should help distinguish them.

    • Calcification and cortical remodeling may be seen.

    • Contrast enhancement is unusual. 2

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Jun 28, 2020 | Posted by in NEUROLOGICAL IMAGING | Comments Off on 6 Choroid Fissure Cyst
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