Male, 40 years old, with five days of unremitting migraine headache and one episode of vomiting. An ill-defined, bubbly multicystic lesion is demonstrated centered on the cerebellar vermis. Several of the small cysts suppress on FLAIR while others do not. The intervening vermian parenchyma is somewhat deformed, but no additional lesional tissue is suspected. No pathologic lesional enhancement is seen. However, there is one ill-defined focus of susceptibility within the lesion which could reflect blood product or mineralization. No large or abnormal vascular structures are suspected on either the postcontrast or susceptibility weighted images. The vermis may be very slightly expanded, but overall, no significant mass effect is seen. The contour of the fourth ventricle remains within normal limits.No additional lesions are seen. Morphology and signal characteristics of the supratentorial brain are within normal limits. No pathologic intracranial enhancement is seen. No abnormal extra-axial fluid collections are detected. There are no findings to suggest acute intracranial hemorrhage. The ventricular system is within normal limits.
A bubbly appearing lesion is seen centered quite specifically in the cerebellar vermis which appears to be composed of numerous cysts and the deformed intervening vermian parenchyma. No pathologic enhancement is seen. No enlarged or abnormal vessels are detected. The lesion exerts little if any mass effect. There is one focus of associated susceptibility which could reflect blood product or mineralization.The differential diagnosis for this lesion is broad and would include a congenital dysplasia, sequelae of prior inflammation or infection, low-grade potentially involuted tumor, or an atypical presentation of Lhermitte-Duclos. A vascular malformation is considered unlikely.