MRI shows an 11mm superficial mass lesion of the nasal bridge. The differential diagnosis includes nasal glioma, dermal cyst, or dermal sinus.
Squamous-lined cyst with keratinous debris as well as sebaceous sweat gland elements (upper right) are present in this dermoid cyst.
Epidermoid cysts consist with stratified epithelium with keratin formation whereas dermoid cysts also contain adnexal structures such as sebaceous glands and hair follicles (Fletcher). They comprise approximately 1% of primary intracranial tumors. Although benign, these cysts can rupture and lead to inflammation of the surrounding parenchyma.
These cysts are slow growing and can be clinically silent for years. Broadly, they can be extradural or intradural. Intradural tumors are harder to excise since they are in close proximity to neurovascular structures (Gormley).
The most common location is the cerebellopontine angle; other sites include prepontine cisterns, sellar region and ventricular system (ie. the lateral and fourth ventricles)(Meng).
Intradural lesions commonly causes headache, visual deficits, and seizures, whereas extradural lesions present with asymptomatic scalp masses (Gormley).
Complete excision is the goal. For intradural cysts, complete removal may not be possible since they may be in close proximity to critical neurovascular structures.
Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 1721.
Gormley WB, Tomecek FJ, Qureshi N et al. Craniocerebral epidermoid and dermoid tumours: a review of 32 cases. Acta Neurochir (Wien). 1994;128(1-4):115-21.
Meng L, Yuguang L, Shugan Z et al. Intraventricular epidermoids. J Clin Neurosci. 2006 May;13(4):428-30. Epub 2006 Mar 27.