Nodular Regenerative Hyperplasia Suggested by Noninvasive Findings during Adjuvant Trastuzumab Emtansine Therapy for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

Introduction

Trastuzumab emtansine (T-DM1) is the standard adjuvant therapy for patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer with residual invasive disease after neoadjuvant chemotherapy. It is generally well tolerated. However, nodular regenerative hyperplasia (NRH), presenting as newly detected hepatic nodules, is a rare hepatic adverse event of T-DM1 that requires differentiation from liver metastasis. Here, we report a patient with HER2-positive breast cancer who developed new hepatic nodules during adjuvant T-DM1 therapy; NRH was suspected based on noninvasive findings.