Intracranial epidermoid tumors. A continuing diagnostic challenge.

Epidermoid tumors are benign, slowly growing intracranial masses that still present difficulty in preoperative diagnosis. This article reviews six cases of histologically proven epidermoid tumors. Computed tomography and magnetic resonance imaging were complementary in their evaluation. Computed tomography demonstrated a hypodense, smoothly contoured extra-axial paramedian mass with lower density than cerebrospinal fluid. Magnetic resonance imaging usually demonstrated an irregularly but sharply marginated mass with inhomogeneous density, variable enhancement with gadolinium, lack of edema in adjacent normal structures, extensive insinuation into cisternal and other cerebrospinal fluid spaces, and a high-signal intensity on proton-weighted images. Multiplanar magnetic resonance imaging was extremely helpful in displaying the full anatomic extent of the lesion and its relationship with other structures.

Concha bullosa: CT evaluation.

Aeration of the middle turbinate, termed "concha bullosa," is a common anatomical variant of intranasal anatomy. Of 320 patients evaluated for sinus disease with coronal CT, 34% had concha bullosa on at least one side. The overall incidence of inflammatory disease in the ostiomeatal complex in these symptomatic patients was not different between those with and without concha bullosa. However, there were many cases in which an abnormally large middle turbinate appeared to obstruct the ostiomeatal complex causing secondary infection of the ethmoid, frontal, and maxillary sinuses. Obstruction of drainage of the concha bullosa itself can lead to mucocele formation. Furthermore, the presence of a concha bullosa has important implications for the technique of endoscopic surgery used in the management of the sinus disease. The anatomy, pathophysiology, and CT findings in patients with concha bullosa are reviewed.