16.表皮樣囊腫（epidermoid tumor）腦瘤會有下列何種特質？
(A)細菌性腦膜炎（bacterial meningitis）
(B)伴有先天異常（associated congenital malformations）
(C)對放射性治療有效（responsive to radiation therapy）
(D)無菌性腦膜炎（aseptic meningitis）

Intracranial epidermoid cysts are uncommon congenital lesions which account for about 1% of all intracranial tumors. They result from inclusion of ectodermal elements during neural tube closure, and typically present in middle age due to mass effect on adjacent structures. Their content, derived from desquamated epithelial cells, mimics CSF on CT and MRI, with the exception of DWI which demonstrates restricted diffusion. Management is surgical and prognosis is good.

Clinical presentation

Signs and symptoms of epidermoid cysts are due to gradual mass effect, with presentation including 4:

headaches: most common

cranial nerve deficits

cerebellar symptoms

seizures

raised intracranial pressure

Recurrent aseptic meningitis is uncommon but recognized.