Severe Thrombocytopenia after the First Trastuzumab Treatment

Abstract

An 81-year-old woman underwent partial mastectomy for left-breast cancer and received adjuvant therapy of trastuzumab. Two days after the first infusion, the patient returned to the emergency department where oral bleeding and generalized purpura were found. Although her platelet count was 0.1×10⁴/μL, the leukocyte and hemoglobin counts were normal. We diagnosed severe thrombocytopenia induced by trastuzumab and the patient was immediately admitted. She was treated with corticosteroid and platelet transfusion therapy. The generalized purpura disappeared 14 days after the first trastuzumab infusion, but her platelet count remained at 1×10⁴/μL. Platelet count was elevated to 4.7×10⁴/μL 22 days after the first trastuzumab infusion, and was subsequently normalized 29 days after the infusion. The patient refused readministration of trastuzumab treatment. Severe thrombocytopenia induced by trastuzumab is a very rare case in Japan. We report a case of severe thrombocytopenia after the first trastuzumab treatment.