Within the realm of oncology, there exists a type of cancerous growth known as a malignant tumor that originates from the duct cells located within a gland. This particular form of tumor develops when the duct cells undergo abnormal and uncontrolled growth, resulting in the formation of a cancerous mass. The malignant nature of this tumor implies its potential to invade surrounding tissues and spread to other parts of the body, necessitating prompt diagnosis and appropriate treatment to manage and mitigate its harmful effects.