SHM Converge Scientific Abstract ePoster Gallery-Undifferentiated Breast Adenocarcinoma Manifesting as Duodenal Obstruction and Hydrourteronephrosis

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This case describes a 55-year-old woman who presented with abdominal pain, persistent nausea, duodenal obstruction, and bilateral hydroureteronephrosis with acute kidney injury. Initial workup at outside facilities showed a near-complete obstruction at the duodenum, a mass-like area near the pancreatic uncinate process, retroperitoneal inflammatory changes, and hydronephrosis requiring bilateral ureteral stents. Multiple endoscopic evaluations and biopsies were initially benign or nondiagnostic, and the patient was treated empirically for possible autoimmune disease with dexamethasone, without improvement.<br /><br />At a tertiary center, repeat imaging and biopsies again failed to reveal a clear pancreatic or duodenal mass. Autoimmune testing, including IgG4, was negative, and tumor markers were normal. Because the imaging and clinical picture were nonspecific, the differential diagnosis remained broad, including pancreatitis, IgG4-related disease, and retroperitoneal fibrosis.<br /><br />Ultimately, surgical sampling of peritoneal tissue provided the diagnosis. Histology showed infiltrative epithelioid tumor cells in fibroadipose tissue, and immunohistochemistry was positive for CK7, CK5/6, GATA3, and p40, but negative for markers supporting gastrointestinal, lung, gynecologic, or mesothelial origin. These findings indicated undifferentiated adenocarcinoma of breast origin with peritoneal and retroperitoneal spread causing duodenal obstruction and ureteral compression.<br /><br />The report highlights how rare gastrointestinal and retroperitoneal metastases from breast cancer are, how closely they can mimic benign inflammatory or autoimmune conditions, and how repeated biopsies may still be inconclusive. It emphasizes the importance of multidisciplinary collaboration and obtaining adequate tissue for diagnosis. Prognosis is poor when breast cancer spreads to the GI tract and peritoneum, and in this case the patient elected comfort-focused care after diagnosis.

Asset Subtitle

An Q. To

Meta Tag

Author List An Q. To, Jacob Stepherson, Megan Brooks, Zi-on Cheung

Category Clinical Vignettes

Concept Metastatic Breast Cancer

Concept Gastrointestinal Obstruction

Concept Immunohistochemistry

Concept Retroperitoneal Involvement

Concept Peritoneal Involvement

Distinguished Non-Finalist

Presenter Organization University of Queensland-Ochsner Clinical School

Presenting Author An Q. To

Track Adult

Keywords

breast cancer metastasis

duodenal obstruction

retroperitoneal fibrosis

bilateral hydroureteronephrosis

acute kidney injury

peritoneal spread

undifferentiated adenocarcinoma

GATA3 positive

inconclusive biopsy

gastrointestinal metastasis

Metastatic Breast Cancer

Gastrointestinal Obstruction

Immunohistochemistry

Retroperitoneal Involvement

Peritoneal Involvement