[Interdural dermoid cyst of the cavernous sinus presenting with oculomotor palsy: case report].

A 19-year-old female was admitted to our hospital because of diplopia. Neurological examination showed slight anisocoria (right > left), disturbance of ocular movement in upward, downward and medial directions on the right side, and diplopia on upward gaze. Computed tomography (CT) scan demonstrated a well-demarcated cystic lesion in the right parasellar region. The lesion showed non-homogeneous low intensity with a high intensity margin on T1-weighted imaging and high intensity with a low intensity margin on T2-weighted imaging in magnetic resonance image (MRI). The lesion showed enhancement by contrast media on neither CT nor MRI. Cerebral angiography revealed no tumor stains. The lesion was approached via right fronto-temporal craniotomy. The right optic nerve, oculomotor nerve and internal carotid artery were compressed medially by the tumor. The tumor contents appeared to be flaky and greasy containing motor-oil-like fluid, mineralized body, and a few hairs. The tumor was attached to the lateral wall of the right cavernous sinus (inner membranous layer), but was totally resected with careful microscopic dissection. The histopathological examination confirmed the diagnosis of dermoid cyst. The patient's complaint of diplopia showed gradual improvement postoperatively. Supratentorial intracranial dermoid cyst is a rare congenital tumor and, to our knowledge, only one case arising within the lateral wall of the cavernous sinus and presenting oculomotor palsy has been reported. Total removal is ideal and may be possible even when the tumor arises from the lateral wall of the cavernous sinus.