Agranulocytosis Induced by Tamoxifen in a Breast Cancer Patient

Background: The main side effects of tamoxifen are menopausal symptoms. We report a case of agranulocytosis induced by tamoxifen in a 33-year-old woman treated in the adjuvant setting. Case Presentation: Ten days after the beginning of tamoxifen treatment, the patient complained of asthenia and mucositis. Blood testing showed a grade 4 neutropenia (0.06 G/L) without any other major hematologic disorder. Tamoxifen was discontinued, and the patient received granulocyte colony-stimulating factor. Within 2 days, she recovered to a normal granulocyte count. Tamoxifen was then switched to the combination of ovarian suppression (triptorelin) and aromatase inhibitor (anastrozole). Conclusion: Agranulocytosis is a very rare adverse event of tamoxifen.