Duodenal Squamous Cell Carcinoma From Metastatic Spread of Head and Neck Cancer: A Case Report.

We present the case of a 69-year-old man with squamous cell carcinoma (SCC) of the duodenum, which was identified as a metastatic lesion stemming from recurrent head and neck cancer (HNC). The patient, who had a history of hypertension, came to the emergency department with burning abdominal pain that had persisted for a week. He reported being well until he suddenly experienced lower abdominal pain, accompanied by reduced appetite, nausea, and post-meal vomiting. An abdominal CT scan revealed a high-grade mechanical obstruction of the small bowel, with a transition point in the right lower quadrant. A biopsy confirmed that the mass was a moderately differentiated metastatic keratinizing squamous cell carcinoma. Metastasis of head and neck squamous cell carcinoma (HNSCC) to the duodenum is rare, likely due to the unique anatomy of the area, which lacks significant lymphatic drainage. This case brings to our attention the need to consider atypical metastatic sites in patients with HNSCC and highlights the importance of advanced imaging and immunotherapy in the diagnosis and management of such metastases.