Choroidal fissure cyst

# 6148502397

Donato, Angel MD. Figueroa, Ramon E. MD. FACR

Augusta University
1120 15th street
Augusta, GA 30912

Female, 22 year(s)


22-year-old female patient G2P0 at 38 weeks of gestation. Prenatal ultrasound shows fetus with a right perithalamic cystic brain lesion. Further evaluation includes fetal MRI with single shot fast spin echo T2 sequences, post-natal transfontanelle ultrasound and sequencial post-natal MRIs at newborn, 3 months and 6 months of age.


Fetal MRI (Fig. 1) demonstrates a left-sided choroidal fissure homogeneous T2 hyperintense cystic lesion, which causes no entrapment of the temporal horn or ventricular enlargement, nor significant mass effect or midline shift of fetal brain parenchyma. 
Transfontanelle neuro ultrasound (Fig. 2) shows a simple cystic cavity lesion projecting within the medial right temporal lobe, with no asymmetry or internal septations. The ventricles were normal in size and configuration. No intracranial haemorrhage was identified.
The postnatal MRI (Fig. 3) further characterizes it as an extra-axial CSF-like lesion consistent with an arachnoid cyst arising from the margin of the right choroidal fissure and expanding the right perimesencephalic cistern, producing deformity of the medial temporal lobe. The right hippocampal formation and parahippocampal structures are significantly compressed and displaced.