Intraorbital Epidermoid Tumors: A Case Report and a Review of the Literature

Abstract

Epidermoid tumors are uncommon lesions making up approximately 1% to 1.5% of all intracranial neoplasms. 1 They originate during the fourth and fifth weeks of embryonic life when the neural plate invaginates in the dorsal midline to form the neural groove and neural folds. The neural folds then form the neural tube, which separates from the overlying ectoderm. When this sequence of development is imperfect, ectopic epithelium may be deposited at sites between the neural canal and skin, resulting in epidermoid and dermoid tumors. 2,3 We report on a case of a large epidermoid tumor involving three cranial bones (sphenoid, zygomatic, and frontal) that extended from the orbit and into the temporal fossa. Report of a Case A 41-year-old white woman with no significant medical history was referred to us by her ophthalmologist with a chief complaint of asymmetry between her eyes since the age of 4 or 5. She stated that her right eye had always “bulged out of the socket” and that this condition had recently worsened. She did not take any daily medications and she reported no allergies. Physical examination was normal except for a noticeable downward and inward proptosis of the right eye. Her vision was 20/20 bilaterally, and extraocular movements were essentially normal. Computed tomography scan revealed a bone-destroying mass in the right lateral orbital wall and orbital roof that extended into the temporal fossa (Fig 1). The mass was isodense with brain tissue and had well-defined borders. Magnetic resonance imaging showed a hypointense signal on T1weighted images and a hyperintense signal on T2-weighted images (Fig 2). Total surgical excision was recommended, and the patient agreed after receiving a full explanation of risks, benefits, and alternatives. Surgical access was obtained through a frontotemporal craniotomy. A pearly white, cheesy mass that had eroded the bone of the pterion and the orbital roof was identified. The thinned bone was carefully excised with rongeurs and the lesion was removed piecemeal with copious irrigation. After the contents of the cyst were evacuated, the diaphanous capsule was carefully peeled from the dura and periorbita. All eroded bone was also removed to decompress the area. The bone flap was replaced, and closure proceeded uneventfully. Histopathologic analysis of the surgical specimen revealed a stratified squamous epithelial lining with abundant keratin debris (Fig 3). No sebaceous glands, sweat glands, or skin appendages were recognized, and thus a diagnosis of epidermoid tumor was confirmed. The patient recovered uneventfully and remains tumor free at 4 months. There has been dramatic reduction in the proptosis.