Amyloidosis is an uncommon disorder characterized by extracellular deposition of abnormal proteins. Breast involvement has rarely been reported and can clinically be misdiagnosed as breast cancer. A 60-year-old woman presented with a 3-mm diameter mass in the right breast close to a silicon implant positioned 20 years before. A core biopsy, performed to rule out breast cancer, showed amyloid deposit. Further exams confirmed a systemic amyloid light chain amyloidosis. After few months the mass increased causing breast volume and shape distortion. Since breast cancer may be the cause of amyloid deposits or be hidden by it, the patient underwent a bilateral skin sparing mastectomy and expander and fat grafting breast reconstruction. The resection specimens showed amyloid deposits only, no evidence of cancer. At 2 years follow-up, no breast amyloidosis recurrence was shown. Breast amyloidosis is rare but can occur in a plastic surgeon’s practice. It is mandatory to rule out a comitant breast cancer or systemic amyloidosis.