Gastrointestinal Bleed from Erosive Gastritis and Duodenitis: A Sentinel Event of Invasive Lobular Carcinoma of the Breast and a Diagnostic Dilemma.

Metastasis from breast cancer to the gastrointestinal (GI) tract is uncommon, and such events presenting as GI bleeding are exceedingly rare. In some individuals, the absence of classical findings of primary breast cancer coupled with the non-specific nature of GI symptoms may make early detection and diagnosis challenging. Our patient is a 75-year-old female who presented with symptomatic anemia manifesting as progressive dizziness, weakness, and early satiety that developed eight days after right knee arthroplasty. She had a remote history of acid reflux disease and reported regular use of non-steroidal anti-inflammatory drugs (NSAIDs). Physical examination was notable for pallor and tachycardia; the cardiopulmonary examination was otherwise unremarkable and the abdominal examination was normal. A fecal occult blood test was positive. Subsequent esophagogastroduodenoscopy demonstrated significant erosive gastritis and duodenitis that was initially attributed to the patient's NSAID use. However, biopsy showed signet ring carcinoma. No gastric primary tumor was identified on work up. Extensive evaluation ultimately revealed invasive lobular carcinoma of the breast. Notably, no primary breast lesion had been detected on physical examination or breast mammography or magnetic resonance imaging (MRI). Therapy for invasive lobular carcinoma of the breast is substantially different from gastric carcinoma and thus it is important to accurately diagnose the condition early in its course to optimize patient outcomes.