A pathologist is a physician who specializes in the causes and paths taken by different diseases in order to accurately diagnose an illness.
In addition to determining the cause and development of a disease, these specialists also study the changes a disease makes to a body and the consequences of those structural changes.
Pathologists diagnose and determine the characteristics of a disease through the study of biopsies of diseased tissue or of bodily fluids. For example, a pathologist will look at a biopsy of a skin lesion in order to diagnose or rule out skin cancer. A pathologist will also look at a Pap smear in order to check for a gynecological cancer like cancer of the uterus.