Computed Tomography Artifact Created by Air in the X-ray Tube Oil.

A subtle artifact of patchy hypodensities in computed tomography images of the head mimicked acute or subacute cerebral infarct. The cause of the artifact was air in the oil of the x-ray tube. The artifact manifested only when the acquisition parameters included a rotation time of 0.5 second and a gantry tilt angle of 11 to 20 degrees. Routine quality control testing did not detect nonuniformities in the water phantom.

Lymphoepithelial cyst as a herald of HIV seropositivity in a patient with known history of neurocysticercosis and suspected parotid cysticercosis.

Among those with acquired immune deficiency syndrome, salivary gland pathology and other less common signs of human immunodeficiency virus (HIV) seropositivity are emerging. Generally speaking, lymphoepithelial lesions of the parotid gland are uncommon with a reported incidence of 0.6%, but they are beginning to overtake other oral lesions such as candidiasis as predominant oral manifestations of clinical HIV infection. Here, we describe a patient with a known history of neurocysticercosis with presumed extracranial cysticercosis as demonstrated by the clinical manifestation of bilateral parotid gland swelling and a ring-enhancing, hypodense lesion of the left parotid gland on CT. He was found to have a lymphoepithelial cyst arising in a lobe of the left parotid gland per pathological evaluation after left superficial parotidectomy, and this served as the initial sign of HIV positivity, which was confirmed by serological studies.