Primary breast angiosarcomas are more likely to harbor PIK3CA mutations (as seen in our patient (table 2)).8 A subset of angiosarcomas of the scalp and face harbor high TMB and a pattern of DNA damage consistent with ultraviolet (UV) light exposure, suggesting that this subset might be uniquely susceptible to ICI.8 11 Indeed, one of the responding patients in our study with angiosarcoma of the scalp had a high TMB (table 2). Here, PIK3CA is linked to breast angiosarcoma.