Can Fat necrosis developed 4 almost 5 months after a breast reduction.

The vascular insult that led to fat necrosis probably occurred at the time of the operation. Acute swelling will camouflage the temporary damaged area. As a swelling subsides a lump may become apparent many weeks after the operation.

Any mass on the breast needs to be checked regardless of it occuring after surgery.  It more than likely is just fat necrosis but it warrants at least some imaging to be sure.  Best wishes, Dr. T. 

Thank you for your question.  While it is unlikely that you have developed new fat necrosis, it is possible for it to become noticeable in a delayed fashion.  As the edema of the tissue resolves and the necrotic tissue hardens, it can become more evident.  Other causes of painful masses include breast cysts.  It should be evaluated by your doctor.  Given the timing, you are also problably due for a new postop baseline mammogram, so checking would be a good idea. Best wishes.