The discovery of a subcutaneous lump or an unusual skin tag or mole can be a source of concern for most people. A professional examination of the growth or tumor often provides answers about its nature and its potential for future harm. A tumor or growth could be considered benign, precancerous, or malignant depending on its structure and root cause. The best case scenario would be a benign tumor, which poses little to no harm, while the worst case scenario would be a malignant tumor, indicating a dangerous cancerous growth has already developed.
A benign tumor or growth differs from a malignant or precancerous growth in one major respect: the tumor's structure is self-contained, meaning it will not seek out other tissue to consume or spread to other parts of the body. This does not mean that the tumor will be completely painless or not grow in size, but it will not destroy surrounding tissue and will not become malignant over time. Many of these tumors or growths can be addressed medically or surgically without the need for cell-killing radiation or chemotherapy regimens.
A tumor or growth diagnosed as malignant, however, is by definition a cancerous situation. A malignant tumor contains cells that have begun to grow uncontrollably and actively seek out more tissue to consume. A malignant growth is not self-contained like a benign growth, and it will continue to spread as long as it continues to find healthy tissue. Pieces of a malignant tumor could break off from the original source and spread to other parts of the body as well.
There is also a condition which falls somewhere between benign and malignant. Certain growths or tumors have the potential to become malignant, but their cell growth has not yet become uncontrolled. A number of skin tags and moles fall under this description of precancerous. A precancerous tumor or growth is not completely harmless, but it has not become aggressive enough to be considered malignant. The precancerous growth may respond well to medical or surgical intervention, but a medical professional may want to observe its behavior before risking a conversion to full-blown malignancy.
In short, a benign tumor is self-contained and should pose no long-term harm. A malignant tumor contains active cancer cells and may require aggressive treatment before long-term damage occurs. A precancerous tumor has the potential to become malignant, but in its current state is only a cause for heightened concern and closer observation.