Introduction Trastuzumab emtansine is an antibody-drug conjugate targeting the human epidermal growth factor receptor 2 use in recurrent metastatic breast cancer. Cases of trastuzumab emtansine-induced nodular regenerative hyperplasia are often reported as overt noncirrhotic portal hypertension with ascites and variceal bleeding. Case report We report the case of a 61-year-old woman who present multiple stellate angiomas with gradual increased liver transaminases and reduced platelet count during a 27-months course on trastuzumab emtansine therapy for recurrent metastatic breast cancer. After the nodular regenerative hyperplasia was histologically confirmed, the trastuzumab emtansine was stopped. After two months, trastuzumab was restarted together with exemestane. During trastuzumab therapy, the patient had a normalization of liver transaminases, platelet count and a gradual improvement of her stellate angiomas. Trastuzumab was continued for 15 months without any reoccurrence of nodular regenerative hyperplasia. Management and outcome Nodular regenerative hyperplasia should be suspected after one year of trastuzumab emtansine treatment in patients with signs of portal hypertension without cirrhosis. Definitive cessation of trastuzumab emtansine is required after a diagnosis of nodular regenerative hyperplasia and complete resolution of symptoms generally takes several months. Discussion Based on fundamental studies, nodular regenerative hyperplasia is probably caused by the emtansine (DM1) part of the trastuzumab emtansine. It is still unclear if trastuzumab therapy can be reintroduced after nodular regenerative hyperplasia induced by trastuzumab emtansine, depriving the patient of a HER2-targeted therapy. Only one case reported having given trastuzumab in this situation over one month. In our case, trastuzumab was reintroduced without any complications for a long extent following TDM1-associated nodular regenerative hyperplasia.