10-year-old female with arachnoid cyst experiencing dizziness Redemonstrated is an approximately 32 x 27 mm extra-axial cystic lesion interposed between the left frontal lobe and frontal calvarium. The lesion does not enhance and follows CSF signal characteristics on all sequences. The lesion exerts mass effect on the adjacent frontal lobe which is compressed and displaced posteriorly. The parenchyma surrounding this lesion, however, is free of any pathologic signal alteration, edema, or enhancement.No additional abnormality is detected. The remainder of the brain demonstrates normal morphology and signal characteristics. Diffusion weighted images are unremarkable. No pathologic parenchymal or extra-axial enhancement is seen. There is no evidence of intracranial hemorrhage. The ventricle system is normal in size and morphology.
Stable left frontal arachnoid cyst exerting mass effect on the adjacent frontal lobe. The brain parenchyma, however, is free of pathologic signal alteration.