Large mammary hamartoma of axillary supernumerary breast tissue.

Hamartoma is an uncommon breast tumor and it is extremely rare to find it in ectopic breast tissue. We report the first case, to our knowledge, of a large hamartoma axillary supernumerary breast tissue. This report describes the case of a 33-year-old Brazilian patient who detected a lump in her left axillary supernumerary breast tissue at the same time as she was diagnosed with systemic erythematous lupus and corticoid treatment was initiated. The lesion showed progressive growth, reaching considerable proportions within a year, and it was removed with good esthetic and functional results.