Teaching File Series

M R I - Division

Complaint : 40Y, Female c/o seizures on and off since 14 years.

FINDINGS:

CT:  Large lobulated cystic mass with peripheral calcification in the right temporo-frontal region compressing right lateral ventricle & obstructive dilatation of left lateral ventricles.

MRI :  Appears hypointense on T1W,  hyperintense on T2W & DWI. On ADC hypointense with incomplete suppression              on FLAIR.

DIAGNOSIS:  EPIDERMOID CYST.

DISCUSSION : Congenital Epidermoid cyst arise from ectodermal inclusion during neural tube closer. Acquired Epidermoid cyst is uncommon and as a result of trauma. Epidermoid cyst is most common congenital intracranial tumor.  0.2 to 1.8 % all primary intracranial tumor. It grows by progresive desquamation with conversion to keratin / cholesterol crystals. It is soft pliable, conforms to shape of adjacent local structures / spaces.

                         Presents at 20 to 60 year with peak at 40 years. Most commong symptom headache, Cranial nerve 5, 7, 8 neuropathy. Seizures if in sylvian fissure / temporal lobe. May remain clinically silent for many years.

                       90% intradural, primarily in basal cisterns. CP angle 40 to 50%. Parasellar / middle cranial fossa 10 to 15 %.  On CT scan apears isodense to CSF in >95% & calcification in 10 to 25%.  On MRI slightly hyperintense to CSF on T1 W & isointense to CSF on T2 W. Usually on FLAIR doesnot completely null. DW shows restricted diffusion and yields high signal & ADC isointense to brain parenchyma.

CSF like mass imaging and shows restricted diffusion is diagnositc of epidermoid.

REFERENCE : Osborn AG, Blaser SI, Diagnostic Imaging, Brain 1st edition, 2004.

SUBMITTED BY:  DR. M.ADINARAYANA RAO. MD.

                              DR. SUNIL ALMALE. DMRD.