Medical

A result that appears negative when it should not.

An antibody that is measurable in the blood. Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis.

The process of straitening or the state of being strait. Extension of the hip and knee joints is necessary to stand up from the sitting position.

A crater in the lining of the esophagus that is created by the corrosive acidic digestive juices secreted by the stomach cells. Ulcer formation is related to the presence of Helicobacter pylori (H.

A narrowing or closure of the normal opening of the swallowing tube that leads to the stomach, usually caused by scarring from acid irritation.

A condition wherein stomach contents regurgitate or back up (reflux) into the esophagus (a long cylindrical tube that transports food from the mouth to the stomach).

A malignant tumor of the esophagus. The risk of cancer of the esophagus is increased by long-term irritation of the esophagus, such as from smoking, heavy alcohol intake, and Barrett esophagitis.

An abnormal reddened patch with a velvety surface that is found in the mouth. Erythroplakia carries an increased risk for becoming a cancer in the oral cavity.

A virus in the herpes family that is best known as the cause of infectious mononucleosis (also called mono and glandular fever). Abbreviated EBV.

Cancer that begins in the cells that line an organ.