Ado-trastuzumab emtansine associated spider telangiectasia.

Introduction: Breast cancer is the most common cancer in women. Human epidermal growth factor receptor 2 (HER2) positivity rate is 20% and generally has a poor prognosis. Ado-trastuzumab emtansine (T-DM1) is an antibody-drug conjugate consisting of HER2 target monoclonal antibody trastuzumab and microtubule inhibitor emtansine.