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| LETTER TO EDITOR |
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| Year : 2012 | Volume
: 60
| Issue : 4 | Page : 441-442 |
Occipital lobe epidermoid cyst
Sukhdeep S Jhawar, Sarvpreet S Garewal, Raghav Wadhwa, Toshi Nandi Shadangi, Pranshu Bhargava
Department of Neurosurgery, Christian Medical College and Hospital, Ludhiana - 141008, Punjab, India
| Date of Web Publication | 6-Sep-2012 |
Correspondence Address:
Sukhdeep S Jhawar
Department of Neurosurgery, Christian Medical College and Hospital, Ludhiana - 141008, Punjab
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.100730
How to cite this article:
Jhawar SS, Garewal SS, Wadhwa R, Shadangi TN, Bhargava P. Occipital lobe epidermoid cyst. Neurol India 2012;60:441-2 |
Sir,
Epidermoid cysts are rare intracranial lesions and account for 0.2-1.5% of all intracranial space-occupying lesions. [1] They are commonly located in the cerebellopontine angle and parasellar area. [1],[2] Other rare locations include brainstem, intraventricular, pineal gland, cavernous sinus and intracerebral. [1],[2],[3] Intracerebral epidermoid cysts are very rare and are commonly located in the frontal and temporal lobe. [4]
A 22-year-old male presented with dull aching holocranial headaches of two years' duration. Two months before admission the patient noticed sudden-onset flashes of light in his visual field for a few seconds followed by an episode of generalized tonic-clonic convulsion. Magnetic resonance imaging (MRI) of brain revealed a well-demarcated right occipital cystic mass lesion [Figure 1]. The lesion was hypointense on T1-weighted and brightly hyperintense on T2- weighted imaging [Figure 1]a and b. There was no post-contrast enhancement [Figure 1]c. The lesion exhibited hyperintense signal on diffusion-weighted imaging (DWI) and internal heterogeneity was noticed on fluid attenuated inversion recovery (FLAIR) imaging [Figure 1]d and e. Patient underwent right occipital craniotomy. Lesion was entirely intra-axial with thick layer of arachnoid covering the medial side of the lesion. Histopathological examination confirmed the lesion to be epidermoid cyst [Figure 2]. | Figure 1: Magnetic resonance image of the brain: (a) T1-weighted axial image showing well-defined hypointense cystic lesion of the occipital lobe. (b) T2-weighted axial image demonstrates the lesion to be brightly hyperintense. (c) Post-gadolinium axial image showing no enhancement of the lesion. (d) Diffusion-weighted axial image showing the lesion to be brightly hyperintense. (e) Fluid attenuated inversion recovery axial image showing internal heterogeneity giving dirty mop-like appearance
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 | Figure 2: Histopathological examination of the lesion shows a cyst wall lined by stratified squamous epithelium with overlying lamellated keratin suggestive of epidermoid cyst (H and E, × 200)
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Pathogenesis of epidermoids is neuroectodermal in origin. [1],[2] These tumors are thought to arise from ectodermal inclusions during neural tube closure in the third to fifth weeks of embryogenesis. At this time of embryogenesis the optic and otic vesicles are being formed, and this could explain the frequent occurrence of epidermoid cysts in the cerebellopontine angle cistern and the parasellar region. Ectodermal inclusions occurring before the third week of embryogenesis could account for the intracerebral and intraventricular location of epidermoids. [4] Epidermoid cysts have an extremely slow linear growth rate. Thus the onset of symptoms and signs is often slow, over a period of months to years. Causes of rapid onset of symptoms include hemorrhage, trauma, chemical or bacterial meningitis, malignant transformation and acute brain swelling. [3] Epidermoid cysts classically demonstrate inhomogeneous hypointense signal intensity on T1- weighted images and inhomogeneous hyperintense signal on T2-weighted images. Epidermoid cysts show restricted diffusion with higher signal intensity than that of cerebrospinal fluid on DWI. [1],[2] Although the cystic appearance and the unusual location as seen in the present case bring other lesions such as an oligodendroglioma and ganglioglioma into the differential consideration, these tumors have not been described to have a hyperintense signal on DW imaging. MRI findings, in the absence of DWI, are not specific and these intracerebral lesions are often mistaken for low-grade astrocytoma or oligodendroglioma.
| » References | |  |
| 1. | Conley FK. Epidermoid and dermoid tumors: Clinical features and surgical management. In: Wilkins RH, Rengachary SS, editors. Neurosugery. New York: McGraw-Hill; 1996. p. 971-6. 
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| 2. | Russell DS, Rubinstein LJ. Tumors and tumor like lesions of maldevelopment origin. In: Russell DS, Rubinstein LJ, editors. Pathology of Tumors of the Nervous System. London: Edward Arnold; 1989. p. 693-9.
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| 3. | Netsky MG. Epidermoid tumors. Review of literature. Surg Neurol 1988;29:477-83.
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| 4. | Kaido T, Okazaki A, Kurokawa S, Tsukamoto M. Pathogenesis of intraparenchymal epidermoid cyst in the brain: A case report and review of the literature. Surg Neurol 2003;59:211-6.
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[Figure 1], [Figure 2]
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