Pertuzumab and trastuzumab are monoclonal antibody inhibitors targeting human epidermal growth factor receptor 2 (HER‐2) and are increasingly being utilised in the management of HER2‐positive breast cancer, having been demonstrated to improve progression‐free survival in conjunction with docetaxel. We present a rare presentation of a lichenoid drug eruption, in an annular atrophic variant, in a 35‐year‐old woman after initiation of HER2‐inhibitor (pertuzumab and trastuzumab) therapy for metastatic breast cancer. [ABSTRACT FROM AUTHOR]