Complete response of unresectable maxillary undifferentiated pleomorphic sarcoma with Alluminox photoimmunotherapy.

Undifferentiated pleomorphic sarcoma (UPS) is an aggressive mesenchymal malignancy with a poor prognosis in unresectable head and neck cases. A woman in her late 70s presented with unresectable maxillary UPS (cT4bN0M0, Stage IVB) involving the skull base and showing membranous epidermal growth factor receptor (EGFR) expression in 10%-20% of tumour cells. After a partial response to definitive chemoradiotherapy, she underwent two sessions of Alluminox photoimmunotherapy with Akalux (cetuximab-sarotalocan sodium) activated by near-infrared illumination via transoral and transnasal optical diffusers under intraoperative navigation and cone-beam CT. This technique enables selective tumour ablation, induces immunogenic cell death and offers potential synergy with immune checkpoint inhibitors. She achieved complete radiological and pathological remission with minimal toxicity and remains disease-free with preserved oral function at 8 months.