BACKGROUND Many patients that have undergone mastectomy surgery are left with residual lateral fat under the arm. While the fat may be associated with pain and cause undesirable bulges in clothing and skin irritation, most post-mastectomy patients are not interested in additional surgery. OBJECTIVE Cryolipolysis is a nonsurgical procedure for fat reduction. The procedure is typically performed for aesthetic improvement in the abdomen, thighs, and flanks, but cryolipolysis was explored in this study for reconstructive purposes. Efficacy was evaluated for nonsurgical reduction of lateral chest wall thickness post-mastectomy. METHODS A contoured cup vacuum applicator was used to treat 31 post-mastectomy patients under the arms. All subjects had undergone mastectomy but had never received cryolipolysis or any surgical procedures to reduce lateral chest wall fat. Treatments were evaluated by independent photo review and patient surveys. RESULTS Three blinded, independent physicians correctly identified 84% of the baseline photographs, demonstrating treatment efficacy. The surveys also found that 87% of subjects reported that cryolipolysis met their expectations; 84% noticed reduction in undesirable tissue; 85% reported better bra fit; and 74% noted that clothing fit more comfortably. Patient questionnaires reveal quality of life improvements post-treatment. While 61% of subjects reported pain in the lateral wall prior to the study, when queried post-treatment, only 13% reported pain; the remaining 87% reported no lateral wall pain. CONCLUSIONS Results from this study indicate that cryolipolysis nonsurgically reduces unwanted fat and may reduce discomfort from residual lateral chest wall fat in post-mastectomy patients. METHODS