Duodenal metastasis from breast carcinoma presenting with refractory nausea and vomiting: a case report.

Breast carcinoma rarely metastasises to the gastrointestinal tract, and duodenal involvement is particularly uncommon. We describe a patient with a complex history of recurrent invasive ductal breast carcinoma who presented with persistent nausea and vomiting refractory to conventional therapy. Endoscopic evaluation revealed mucosal nodularity in the second portion of the duodenum. Biopsies confirmed metastatic breast carcinoma immunohistochemically positive for GATA3 and mammaglobin, and negative for CK20, indicating breast origin. This case highlights the importance of considering gastrointestinal metastasis in patients with prior breast cancer presenting with gastrointestinal symptoms. Early endoscopic assessment and immunohistochemical confirmation were key to diagnosis. Clinicians should maintain a high index of suspicion for atypical metastatic patterns in patients with advanced breast carcinoma.