Tx and Followup:
Dermoid surgically removed. Patient presented on follow-up exam with focal seizures v. new onset movement disorder. Follow-up MRI did not identify any residual tumor, however, a small deep right hemispheric infarction in relationship to the anterior caudate and inferior deep hemispheric structures was noted.
Dermoid cysts are believed to arise from congenital rests of epithelial cells and skin tissue that remain in the intracranial cavity as a result of incomplete separation of the neuroectoderm from the cutaneous ectoderm at the time of neural tube closure. They are likely to present as midline masses (as opposed to epidermoids), mostly in the pineal and suprasellar regions, due to the earlier inclusion of ectoderm into the neural tube. They may contain ectodermal glands such as apocrine glands and hair follicles. Teeth may also be found. They are rare neoplasms as they account for less than 1% of all intracranial tumors. The slow growth rate of dermoids delays the clinical presentation until the 3rd or 4th decade of life. The clinical presentation is variable and nonspecific. Headache, seizures and dementia have been described. A ruptured cyst may present as chemical meningitis from leakage of cystic contents into the CSF. Rarely patients with ruptured dermoids cyst may be asymptomatic. MR findings of dermoid tumors include heterogeneous mass usually at the midline. Sometimes fluid- fluid levels are observed. The lesion appears hyperintense on T1W imaging while on fat suppressed T1W imaging the mass loses signal. The dermoid tumor has to be differentiated from an epidermoid. The location of epidermoids shows a much greater variation as well as a greater tendency to deviate from the midline. The most frequent site is the cerebellopontine angle, followed by the suprasellar region and the middle cranial fossa. Although epidermoids may present at any age, most are diagnosed during the fifth decade.