What is a "lesion" A lesion is a non-specific and meaningless term meaning there is "something" seen in the liver that shouldn't be there. It can be very serious, or can mean little or nothing. Depends on what the lesion is - a benign tumor, a cancer, an infection, tuberculosis, a cirrhotic nodule - all are lesions. At 26, i hope you aren't speaking of yourself. Lesions need a biopsy or some specific diagnosis.