RESUMEN
BACKGROUND: We present the case of a recurrent malignant phyllodes tumor of the breast, after mastectomy and radiotherapy, in which electrochemotherapy (ECT) was applied to the tumor bed, to achieve better local control. CASE REPORT: A 66-year-old woman with a large malignant phyllodes tumor of the right breast with a size of 40 cm underwent right radical mastectomy and right axillary lymph node sampling. One month after surgery, with histologically clear margins, the woman presented with multiple small oval masses in the upper portion of the chest wall, indicating rapid disease progression. A second radical excision with clear margins was performed, followed by adjuvant radiotherapy. Two months after the end of treatment, a new 3-cm mass was present in the right axillary extension. The patient underwent a third extensive debulking surgery. At the end of the resection, ECT was applied on the tumor bed along the extensive skin flaps and resection margins. After eight months of follow-up, breast magnetic resonance imaging and total body computed tomography showed disease recurrence in the anterior portion of the right serratus muscle and in the lungs bilaterally. The area undergoing previous ECT showed no disease recurrence. The patient received two lines of palliative chemotherapy. She died 28 months after diagnosis. At the time of death, the large area treated with ECT was geometrically spared from local disease progression. CONCLUSION: This case report suggests the potential efficacy of ECT at the operating bedside to increase local control in aggressive malignancies.