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What is Which of the following is not a characteristic of malignant lesions? and explain in detail?
The periphery most often is ill defined and has an invasive characteristic commonly seen in malignant tumors.
The imaging presentation of malignant tumors is variable and is related to the grade, aggressiveness, location, and type of tumor. In many cases, it is impossible to determine whether a tumor  is malignant or benign. However, features such as ill-defined margins, invasion of adjacent soft tissues (e.g., fat spaces), and destruction of adjacent osseous structures are considered to be typical  indicators of malignancy.
Oral radiology White and Pharaoh; 7th ed. Page no 557