Low-attenuation lesions in the middle cranial fossa: differential diagnosis

The reliability of cranial computed tomography (CT) in detecting a broad range of intracerebral disorders has been well established (1) and its complementary role with other neuroradiologic procedures has been documented (2). Some attempts at inferring specific histologic diagnosis from static CT scans have been made (3,4). However, other investigators have demonstrated that it is difficult to separate cystic from noncystic, benign from malignant, and neoplastic from non-neoplastic lesions by absorption coefficients alone (5,6). While initial studies utilizing dynamic CT scanning indicate that patterns of contrast accumulation may be helpful in distinguishing enhancing cerebral lesions (7,16), the differential diagnosis of the low-attenuation lesion remains difficult (17). We present a series of hypodense lesions in the middle cranial fossa that demonstrate a broad range of pathologic entities. Their CT features, differential diagnosis, and pathologic correlation are discussed.