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ABSTRACT ID: IRIA - 1044.  51 year old male came with complaints of chronic headache.  He had 3 episodes of generalized seizures.  There is weakness.

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Presentation on theme: "ABSTRACT ID: IRIA - 1044.  51 year old male came with complaints of chronic headache.  He had 3 episodes of generalized seizures.  There is weakness."— Presentation transcript:


2  51 year old male came with complaints of chronic headache.  He had 3 episodes of generalized seizures.  There is weakness of all four limbs.  There is no history of fever, trauma.  Blood parameters were normal.  Patient was referred for MRI brain.

3 MR imaging of the brain revealed an extra-axial, lobulated ill defined mass occupying the fourth ventricle with extension into CP angle which is hypo intense on T1 & hyper intense on T2 insinuating the vessels around CP angle with no evidence 0f blooming on gradient imaging with no enhancement in contrast.

4 The Fourth ventricle mass which is iso intense to CSF in T1 & T2 is appearing of mixed intensity in FLAIR sequences (not suppressed completely). The mass is causing mild dilatation of lateral ventricles.

5  The lesion had homogeneous CSF intensity on both T1- weighted and T2-weighted images and remained hypo intense on FLAIR sequences.  There is no evidence of any altered signal intensity within the mass lesion.

6  Epidermoid cyst, or pearly tumour, is congenital in origin and accounts for about 1% of intracranial tumours.  It is a benign extra cerebral intradural lesion and in about 40% of cases is located in the cerebellopontine angle.  They are believed to form between the 3rd and 5th week of embryonic development as a result of displaced epithelial remnants that remain after the neural tube closes.

7  Although acquired epidermoid tumours may develop as a result of trauma, this is uncommon in the brain.  Grossly, epidermoid tumors are typically well defined lesions with an irregular nodular outer surface and a shiny “mother of pearl” appearance.  The cyst content is derived from desquamated epithelial cells composed mainly of keratin in concentric layers and cholesterol in a solid crystalline state.

8  On MR imaging, epidermoid tumours typically have low signal intensity on T1-weighted images, high signal intensity on T2- weighted images, and no enhancement on gadolinium-enhanced images.  Epidermoid tumors showing unusual signal intensity changes have been reported.

9  The tumour can be a so-called white epidermoid with short T1 values and fatty attenuation on CT, characterized surgically as being cystic and having a high lipid content comprising mixed triglycerides containing unsaturated fatty acid residues, and no cholesterol.  It can show hyper intensity on T1- and T2-weighted MR images, caused by a semi liquid cystic content with high protein concentration.

10  The intra cystic haemorrhage can cause a high signal intensity on both T1- and T2-weighted images because of the paramagnetic effect of heme iron (Fe3) in methemoglobin and other haemoglobin breakdown products.

11  CSF collections, e.g. Arachnoid cyst or mega cisterna magna  Less lobulated follows CSF on all sequences, including FLAIR and DWI  Dermoid cyst  Often fat density due to sebum  Inflammatory cyst, e.g. Neurocysticercosis  Smaller, but may be multiple  May enhance peripherally  May have associated oedema  Usually no restricted disffusion  Cystic tumour, e.g. Acoustic schwannoma or craniopharyngioma  Solid enhancing component is usually identifiable  Neurenteric cyst

12  Epidermoid cysts typically show undulating margins and model their shape to conform to the cerebropontine angle.  The cyst has a tendency to insinuate itself around the nerves and blood vessels in the cerebropontine angle.  They usually do not enhance with gadolinium and do not bleed.  From a practical point of view, recognition of case as a hemorrhagic epidermoid cyst is important.

13  Mohanty A, Venkatrama SK, Rao BR, et al. Experience with cerebellopontine angle epidermoids. Neurosurgery 1997;40:24–30 .Tampieri D, Melanson D, Ethier R. MR imaging of epidermoid cysts. AJNR Am J Neuroradiol 1989;10:351–56  Gao PY, Osborn AG, Smirniotopoulos JG, et al. Radiologic-pathologic correlation: epidermoid tumor of the cerebellopontine angle.AJNRAmJ Neuroradiol 1992;13:865–72  Salazar J, Vaquero J, Saucedo G, et al. Posterior fossa epidermoid cysts. Acta Neurichir 1987;85:34–39  de Souza CE, deSouza R, Costa SD, et al. Cerebellopontine angle epidermoid cysts: a report on 30 cases. J Neurol Neurosurg Psychiatry 1989;52:986–90  Ochi M, Hayashi K, Hayashi T, et al. Unusual CT and MR appearance of an epidermoid tumor of the cerebellopontine angle. AJNR Am J Neuroradiol 1998;19:1113–15

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