Pathology is the study of disease. Pathologists are doctors who specialize in pathology and can help determine the cause or causes of a health problem. Pathology tests are performed on samples taken from a patient's body, usually during an examination. The results of these tests are used to diagnose diseases and provide information about how your body works. Pathology tests are also important when you have symptoms that suggest possible diseases but do not meet all the criteria for a specific diagnosis.