Annular atrophic lichen planus induced by anti-HER2 antibodies

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.