A tumor, also known as a neoplasm, is an abnormal mass of tissue which may be solid or fluid-filled. A tumor does not mean cancer - tumors can be benign (not cancerous), pre-malignant (pre-cancerous), or malignant (cancerous). There are many different types of tumors and a variety of names for them their names usually reflect their shape and the kind of tissue they appear in. Put simply, a tumor is a kind of lump or swelling, it does not necessarily pose a health threat.
When doctors use the term tumor they are talking generically and not about the size of the lesion. A mass usually refers to a lump which is at least 20 mm (0.787 inches) in diameter at its widest point, while a nodule is less than 20 mm at its widest point.
Tumor sizes may vary enormously. In January 2012, Nguyen Duy Hai, a 32-year-old Vietnamese man underwent a 12-hour operation to remove a 200-pound tumor from his leg.