Human Epidermal Growth Factor Receptor-2 positive metastatic salivary duct carcinoma with remarkable response to targeted therapy: a case report and therapeutic implications

Salivary duct carcinoma (SDC) is a rare and highly aggressive malignancy that frequently overexpresses Human Epidermal Growth Factor Receptor 2 (HER2). Despite the increasing recognition of HER2-targeted strategies, evidence remains limited and largely derived from small trials and case series. We report the case of a middle-aged man with HER2-positive metastatic SDC who achieved near-complete pathologic and radiological response to trastuzumab and docetaxel, enabling surgical resection for locoregional control. This case highlights the role of anti-HER2 therapy as a first-line strategy in SDC and underscores the importance of individualized management plans integrating systemic treatment and locoregional measures.