Spontaneous Auto-Amputation of the Breast in a Patient With Advanced Malignant Fungating Wound and Distant Metastases Involving the Lungs and Left Upper Extremity: A Case Report.

Malignant fungating wounds in advanced breast cancer cause significant morbidity and psychological distress. Spontaneous auto-amputation of the breast is a rare clinical phenomenon, conventionally linked to neglected tumors rather than actively treated disease. We present a case of spontaneous auto-amputation in an extensively pretreated 60-year-old female with advanced human epidermal growth factor receptor 2-positive (HER2+) breast cancer. She presented to the palliative care unit with refractory left upper extremity pain, severe tactile and thermal allodynia due to malignant brachial plexopathy, and extensive malignant lymphedema complicated by deep vein thrombosis. During her clinical course, despite prior multi-line systemic therapy, rapid local tumor proliferation outpaced neovascularization, leading to critical ischemia, extensive necrosis, and the culminating spontaneous auto-amputation of her left breast. Symptom control required an escalation of pharmacological therapy beyond standard opioid protocols due to inadequate efficacy. To manage the refractory neuropathic pain, the regimen was supplemented with advanced intravenous adjuvant analgesia, bypassing the traditional three-step World Health Organization analgesic ladder. This utilized targeted infusions of lidocaine, magnesium sulfate, and dexmedetomidine. Ultimately, the patient's progressive condition necessitated the implementation of palliative analgosedation to manage refractory distress and maintain dignity. This case highlights that effective advanced management requires dynamic, multimodal palliative strategies, prioritizing the early recognition of complex neuropathic mechanisms and the utilization of advanced intravenous interventions.