I had liposuction of my abdomen and flanks 12 weeks ago. Is a large lump normal or do I have an underlying issue? (photos)

Very good question and thank you for supplying both before and after photos to evaluate.The fullness of your left abdomen may be one of several issues.  First, it may just be residual fat which can be fixed under local anesthesia at a 'touch up' procedure at six months.  Second, it may be a fluid collection called a seroma.  This can be ruled out by either an ultrasound or placing a thin needle into the area to see if fluid can be aspirated.  Third, it may be a weakness of the abdominal wall (hernia) which was present before, but became more prononced after the fat above it was removed.Best of luck.Dr. T

This might be fat but also could be a seroma (fluid collection), less likely a hernia. Would suggest have your surgeon evaluate it, possibly get ultrasound if concerned about fluid collection

It is likely fat but always could be a hernia. I agree to wait at least 4-6 months before doing any touch-up.  Best of luck.