**2. Classification**

Tumors are classified as benign and malignant, depending on the biological behavior of a tumor.

	- Remain localized without invasion or metastasis.
	- Well-differentiated: Their cells closely resemble their tissue of origin.
	- Prognosis: It is very good, can be cured by surgical removal in most patients and the patient generally survives [1].
	- Invasion: Malignant tumors invade or infiltrate into the adjacent tissues or structures.
