Pathology covers the study of diseases and their effects on the body.An ulcer is a sore that forms on the skin or on a mucous membrane.Cysts can occur in various parts of the body, including the ovaries, kidneys, and liver.A tumor is an abnormal growth of cells that can be benign or malignant.A cancer is a condition when there is uncontrolled growth of abnormal cells in the body.Congenital defects can be present at birth and are often caused by genetic factors.The diagnosis of infections often requires laboratory tests, such as blood cultures or microbial cultures.