Inflammation: A reaction, usually mediated by the immune system, to noxious stimuli, manifested clinically by swelling, pain, tenderness, redness, heat, and/or loss of function of the affected part. To a pathologist, however, inflammation means the infiltration of certain immune system cells into the tissue or organ being examined. These inflammatory cells include: 1. Neutrophils, which are the white blood cells that make up pus and are seen in acute or early inflammations 2. Lymphocytes, which are typically seen in more chronic or longstanding inflammations 3. Macrophages (histiocytes), which are also seen in chronic inflammation. Some types of inflammation are readily diagnosable by the primary care physician, such as an infected skin wound that is tender, hot, and draining pus. Other types of inflammation are not so readily apparent clinically and require biopsy to distinguish them from neoplasms. The suffix "-itis" is appended to a root word to indicate "inflammation of ______." For example, cervicitis, pharyngitis, gastritis, and thyroiditis are inflammations of the cervix, pharynx (throat), stomach, and thyroid gland.