case_images: PMC3669468_01
case_images: CT scan brain axial image showing well-circumscribed extra-axial midline hypodense lesion in the posterior fossa (arrow)
case_images: JCVJS-3-16-g001.jpg
case_images: PMC3669468_01_JCVJS-3-16-g001.jpg
case_images: F1
case_images: Computed tomographic (CT) scan of head showed a well-circumscribed extra-axial midline hypodense lesion in the posterior fossa [Figure 1].
case_images: MRI brain: (a) Axial and (b) Sagittal views showing posterior fossa extra-axial well-marginated T1-hypointense, (c) T2-hyperintense non-enhancing midline cyst with hydrocephalus. (d) Coronal view shows elongation of the cyst below foramen magnum
case_images: JCVJS-3-16-g002.jpg
case_images: PMC3669468_01_JCVJS-3-16-g002.jpg
case_images: F2
case_images: T1WI hypointense, T2WI hyperintense non-enhancing cystic lesion with elliptical elongation below the foramen magnum [Figure 2a, b, and d]. There was associated mass effect compressing the 4th ventricle, causing non-communicating hydrocephalus [Figure 2c].
case_images: MRI craniospinal axis sagittal view showing posterior fossa T1WI hypointense, (a) T2WI hyperintense. (b) Cystic mass communicating with the spinal subarachnoid space, compressing and anteriorly displacing the medulla oblongata and proximal cervical cord up to the lower border of C5 (arrow)
case_images: JCVJS-3-16-g003.jpg
case_images: PMC3669468_01_JCVJS-3-16-g003.jpg
case_images: F3
case_images: MRI of craniospinal axis revealed the same cystic lesion extending down through foramen magnum up to the lower border of C5 vertebra, communicating with the spinal subarachnoid space, compressing and displacing the medulla oblongata and proximal cervical cord [Figure 3].
case_images: Photomicrograph of the cyst wall demonstrating a thin arachnoid layer lined by discrete nests of meningothelial cells
case_images: JCVJS-3-16-g004.jpg
case_images: PMC3669468_01_JCVJS-3-16-g004.jpg
case_images: F4
case_images: Histopathologic examination of the cyst wall confirmed it to be an arachnoid cyst [Figure 4].
case_images: Postoperative decreased size of the cyst
case_images: JCVJS-3-16-g005.jpg
case_images: PMC3669468_01_JCVJS-3-16-g005.jpg
case_images: F5
case_images: CT scan done on 8th postoperative day revealed decreased size of the lesion [Figure 5].