S3683 Chronic Diarrhea Secondary to a Metastatic Primary Peritoneal Carcinoma

Abstract

Introduction: We report a case of a patient with chronic diarrhea secondary to a metastatic cancer to small intestine. Causes of diarrhea are multiple including infectious, malabsorption, inflammatory, osmotic and secretory. Diarrhea secondary to metastatic malignancy has been reported mostly in breast cancers with metastasis to the colon. In our case, a metastatic primary peritoneal carcinoma (PCC) was the most likely cause after exclusion of other common etiologies. Case Description/Methods: A 56 year old female with a history of metastatic PCC presented to the hospital with watery diarrhea of two months duration. She reported greater than 10 bowel movement per day. She denied hematochezia, mucus, or fever. In terms of her oncological history, she was diagnosed with PPC 14 years prior to presentation and treated with omentectomy, hysterectomy, and oophorectomy with subsequent adjuvant therapy. Unfortunately, she developed recurrence with metastasis to lymph nodes and liver that failed to respond to chemotherapy and she received only one dose of pembrolizumab 2 months prior to presentation. Her admission vital signs were normal. On exam her mucous membranes were dry and abdominal exam was normal. Laboratory evaluation was significant for white cell count of 24.7 X 103/uL (normal 4.5-11.0 X 103). Stool studies were negative for infection. Upper and lower endoscopy were performed. Colonoscopy revealed normal colonic mucosa and biopsies were negative for microscopic colitis. Upper endoscopy showed a large, infiltrative, ulcerated, and friable mass in second portion of duodenum. Pathology revealed poorly differentiated adenocarcinoma (Figure 1) with ulceration consistent with gynecological origin. Discussion: Diarrhea secondary to metastatic malignancy has been reported mainly in breast cancer patients. Presumably, The pathophysiology in most of these cases is through diffuse colonic invasion and interference with water reabsorption. We presented a rare case of PPC cancer with metastasis to the small bowel and given similarity to epithelial ovarian cancer, it was reported histologically as adenocarcinoma consistent with gynecological origin. The pathophysiology of diarrhea in this situation is presumably malabsorption. Our patient’s prognosis was poor, and she entered hospice care soon after the diagnostic procedures. It is important to consider small bowel metastasis as an etiology of loose stools in patients with a history of cancer and an otherwise negative work up for more common etiologiesFigure 1:: showing normal duodenal mucosa with underlying tumor (A)..