Female, 26 years old, with history of temporal lobe cyst. Evaluate for size and for other lesions. A cyst is present in the left middle cranial fossa, sitting just superior to the temporal lobe, which measures 24 mm AP, 22 mm TV, and 20 mm SI. The cyst follows CSF signal characteristics on all sequences. There is slight mass effect upon the adjacent anterior temporal lobe.The cerebral and cerebellar parenchyma is otherwise within normal limits. No edema or focal signal abnormality is seen. No restricted diffusion is demonstrated. There are no findings to indicate intracranial hemorrhage. Ventricular size morphology are within normal limits. Prominence of the CSF space posterior to the cerebellum could represent a magna cisterna magna or an additional CSF cyst.
Findings are seen compatible with an arachnoid cyst in the left middle cranial fossa. The lesion causes mild mass effect on the adjacent parenchyma. Findings are also seen compatible with mega cisterna magna or perhaps an additional arachnoid cyst in the posterior fossa. The brain parenchyma itself is within normal limits.