There are 3 likely reasons for this lump. A new lesion of some sort, or a slow growing lesion from your original surgery. The second is a small area of fat necrosis that has gotten larger, possibly due to an infection or hematoma, and finally a seroma or fluid collection that is slowly getting larger. A very remote possibility is a small traumatic vascular wekness that is slowly growing and needs to be repaired. The reason for biopsy is to rule out a malignancy. If the area is painful, malignant or not, removal is indicated. I would get the biopsy sooner rathger than later. I hope this helps, respectfully,
arch s miller ms md facs
Thank you very much for the prompt and detailed answer.