topics / مواضيع

  Primary Nonneoplastic Cysts Overview (Left) Gross pathology shows an autopsied case of a colloid cyst, sectioned in the coronal plane through the foramen of Monro. Note the gelatinousappearing lobulated cyst ﬈ with the fornices st straddling the cyst. This patient died of sudden obstructive hydrocephalus. (Courtesy J. Townsend, MD.) (Right) Gross pathology of an autopsied brain, seen from below, shows a large arachnoid cyst of the middle cranial fossa. The cyst contained cerebrospinal fluid within split layers of arachnoid ﬈. (Courtesy J. Townsend, MD.) (Left) Gross surgical specimen of a sectioned dermoid cyst shows the characteristic lining of stratified squamous epithelium plus intracystic keratin debris ſt. Matted, tangled hairs ﬊ are present within the cyst, which contained thick, greasy sebaceous material when sectioned. (Courtesy R. Hewlett, MD.) (Right) Microscopy of a typical dermoid cyst shows squamous epithelium ﬈ and sebaceous glands ﬊ lining a cavity that contains desqua

  Primary Nonneoplastic Cysts Overview Intracranial Cystic-Appearing Lesions Extraaxial Intraaxial Supratentorial Supratentorial Midline Parenchymal Pineal cyst Enlarged PVSs Dermoid cyst Neuroglial cyst Rathke cleft cyst Porencephalic cyst Arachnoid cyst (suprasellar) Connatal, germinolytic cysts Hippocampal sulcus remnants Off midline Intraventricular Arachnoid cyst (middle cranial fossa, convexity) Choroid plexus cysts Epidermoid cyst Ependymal cyst TACs (macroadenoma, meningioma) Colloid cyst Sebaceous cyst (scalp) Leptomeningeal cyst ("growing fracture") Infratentorial Infratentorial Midline Parenchymal Neurenteric cyst Enlarged PVSs (dentate nuclei) Arachnoid cyst Off midline Intraventricular Epidermoid (CPA) Epidermoid (4th ventricle, cisterna magna) Arachnoid cyst (CPA) Cystic ("trapped") 4th ventricle TACs (schwannoma, meningioma) Nonneoplastic, noninfectious cystic brain lesions are classified by common anatomic locations. The 1st division is extra- vs. in

  ular cysts are most often found in the atria of the lateral ventricles and foramen of Monro. CPCs are the most common of all intracranial neuroepithelial cysts, occurring in up to 50% of autopsies. Most CPCs are actually xanthogranulomas. Lipid accumulates in the choroid plexus from degenerating &/or desquamating choroid epithelium. CPCs are common incidental imaging findings in middle-aged and older adults. They are usually bilateral and are often multicystic. Most CPCs are small, measuring 2-8 mm in diameter. They typically do not suppress completely on FLAIR and may show moderately high signal intensity on DWI. Ependymal cysts (ECs) are rare, benign, ependymal-lined cysts of the lateral ventricles. Most ECs, even large ones, are asymptomatic and incidental. EC patients presenting with headache, seizure, &/or obstructive hydrocephalus have been reported in the literature. They contain clear serous CSF-like fluid secreted from ependymal cells. ECs typically follow CSF on all