Ibrahim A. Almahbashi, Abdulmalik A. Qais, Mohammed O. Alabsi
Department of Radiology, faculty of medicine and health sciences, Sana’a university
Most of spinal canal epidermoid cysts are intradural extramedullary in location .Epidermoid cyst within the spinal cord (intramedullary epidermoid cyst) is a very rare condition. Less than 55 cases have been reported in the literature, of these, only 12 cases have been subjected to magnetic resonance imaging (MRI) studies.The first objective of this report is to emphasize the role of MRI in the early diagnosis of intramedullary tumors, analyzing the MRI features of this rare lesion. The second objective is to creat awareness of the possibility of early presentation of such a benign tumor.
A 3 year- old male child was referred to our radiology department for spine MRI because of progressive lower limbs weakness and arching of the back since 3 months.There was no history of trauma, fever or convulsion.The child is vaccinated against polio.The physical examination revealed bilateral decrease of motor power of lower limbs (grade 2-3).The ankle and knee reflexes were slightly exaggerated. There was bilateral decreased proprioception below T12. Upper limbs were normal.Spine CT scan which has been done before (Figure 1)showed ill defined hypodense expansion of the spinal
canal at the level of lower thoracic region, but no well demarcated lesion could be outlined.During this period antibiotics and anti-inflammatory drugs were prescribed but without benefit.
Under general anaesthesia the MRI for the whole spine was performed in sagittal and axial planes using closed type MRI machine of 1.5 Tesla.The used sequences were T1 and T2, as well as, T1 after 2.5ml of Gd-DTPA contrast administration.STIR sequence was not used because no hyperintensity was found on the pre-contrast T1 WI.In the axial cuts, 4mm. slices thickness were applied.
The MRI revealed an intramedullary well defined, smoothly outlined space occupying lesion that expanded the conus medullaris.The vertical diameter of the lesion was about 12mm. The lesion was hypointense on T1 WI and homogenous hyperintense on T2 WI (Figure2a&2b).There was no contrast enhancement at all (Figure2c).The surrounded area of the cord didn’t show edema or satellite focal
lesions.No hydromyelia noticed. The MRI didn’t reveal occult spinal dysraphism.The case was reported as intramedullary cystic lesion of benign character with reference to the possibility of epidermoid cyst.