Primary squamous cell carcinoma of the duodenum: a case report and literature review

Duodenal squamous cell carcinoma is an exceedingly rare occurrence among gastrointestinal malignancies, and its diagnosis and treatment are not well understood. In this report, we present a case of duodenal squamous cell carcinoma with liver and adrenal metastasis. The patient was treated with gemcitabine and S-1, achieving a progression-free survival (PFS) of 7 months and an overall survival (OS) of 9 months. Additionally, we review the features and treatment approaches reported in previous cases of primary duodenal carcinoma. Clearly, further case reports, such as ours, can contribute to a deeper understanding that is essential for characterizing this entity and establishing management guidelines.