Severe thrombocytopenia after trastuzumab retreatment: a case report

BACKGROUND: Trastuzumab prolongs survival of human epidermal growth factor receptor 2-positive breast cancer patients in both the adjuvant and metastatic settings. Currently toxicity data are not available on retreatment of metastatic breast cancer patients who relapse after adjuvant trastuzumab. We report one patient with metastatic breast cancer who developed acute thrombocytopenia after trastuzumab infusion. This patient had trastuzumab treatment in the adjuvant setting. CASE PRESENTATION: A 70-year-old Caucasian woman received a diagnosis of metastatic breast cancer four years after her initial diagnosis of locally advanced, hormone receptors-positive, human epidermal growth factor receptor 2-positive breast cancer. Trastuzumab retreatment was planned. Less than 24 hours after trastuzumab infusion, the patient was admitted to the hospital for the appearance of diffuse petechial hemorrhages and ecchymosis. The patient was confirmed to have a severe trastuzumab-induced thrombocytopenia. A rapid and complete recovery was observed after high-dose intravenous corticosteroids and immunoglobulin. No trastuzumab retreatment was attempted. CONCLUSION: Among the reported cases of trastuzumab-induced thrombocytopenia, this is the first report in the literature occurring in a patient retreated with trastuzumab after adjuvant therapy.