A Curious Case of Gastric Outlet Obstruction!: 2626

INTRODUCTION: The average lifetime risk of a woman developing breast cancer is 12%. Invasive lobular carcinoma (ILC), the second most common histologic type attributes to 10–15% of breast cancer diagnoses. Compared to invasive ductal carcinoma, ILC has a higher chance to metastasize liver, ovaries and even the gastrointestinal tract. We present a unique case of gastric outlet obstruction (GOO) as the initial presentation of metastatic ILC. Histologically, it can be challenging to delineate ILC from primary gastric adenocarcinoma. This was a rare case where the diagnosis was made via the comparison of the endoscopic biopsy with the patient’s previous lymph node pathology. CASE DESCRIPTION/METHODS: 75-year-old female with history of type 2 diabetes mellitus, and lobular carcinoma treated with a bilateral mastectomy and Anastrozole hormone therapy for 8 years presented with confusion and non-bilious, non-bloody vomiting for two weeks. Vitals indicated orthostatic hypotension and abdominal exam revealed a tender epigastrium without rigidity or guarding. Laboratory findings demonstrated severe contraction alkalosis. Abdominal CT with contrast depicted wall thickening in the second and third portion of the duodenum. Endoscopy revealed an infiltrative circumferential mass that stemmed from the antrum extending through to the proximal duodenum causing GOO. The morphological features of the duodenal mass were consistent with biopsy findings of the patient’s previous sentinel lymph node and mastectomy specimen. The diagnosis was further confirmed with immunostains, which were positive for estrogen receptor and mammoglobin, and negative for progesterone receptor and E-cadherin. Patient received robotic gastrojejunostomy tube placement. Her nutritional status improved and was started on chemotherapy. She had a complete metastatic workup which was unrevealing. DISCUSSION: ILC can metastasize later in life to the brain, ovaries and gastrointestinal tract. Isolated duodenal metastasis is limited to only a few case reports. It is theorized in the literature that lack of expression of the adhesion molecule, E-cadherin, may facilitate ILC’s permeation into tissues. This may contribute to metastasis of ILC with a predilection to gastrointestinal and gynecological sites, which generally occurs after a mean duration of 7 years. Our case is rare in that, the patient presented with GOO as the only initial manifestation of duodenal metastasis within 8 years of treatment of ILC without any other evidence metastatic spread.