S3514 A Case of Symptomatic Ileal Non-Secretory Neuroendocrine Tumor Successfully Treated With Octreotide

Abstract

Introduction: Neuroendocrine tumor incidence is steadily increasing, likely from detection due to better imaging, routine colonoscopies, and endoscopies. Most NETs, 55%, are found in the GI tract and only 0.1-1% found on routine colonoscopy. About 40% of NETs are hormone producing leading to the clinical diagnosis of carcinoid syndrome. One of the most common symptoms of carcinoid syndrome is diarrhea occuring in 80% percent of cases, however diarrhea can be present in non-secretory NETs. Here we report a case of GNET presenting as diarrhea that responded to octreotide injections despite having normal 5-HIAA and chromogranin A levels. Case Description/Methods: Our patient is an 80 year old female with past medical history of hypertension, renal stones, and IBS with baseline diarrhea of about 2-4 pasty stools a day. In November she developed two days of severe diarrhea with 10 watery stools a day and multiple episodes of incontinence which prompted patient to go to the ED. The inpatient workup was negative for acute causes, CT showed diverticulosis, and stools returned to baseline. The patient was discharged with outpatient GI follow up. At home the severe diarrhea retuned so outpatient GI planned for colonoscopy. Results of the procedure included a 2cm submucosal non-obstructing mass in the terminal ileum. Pathology showed a G1 well differentiated neuroendocrine tumor. Patient was referred to oncology and workup revealed no metastasis on PET/CT and negative 5-HIAA and chromogranin A levels. During initial oncology visit patient was started on octreotide injections which greatly improved the diarrhea. Even with negative carcinoid workup the decision was made to continue octreotide injections and not to pursue surgical options. (Figure) Discussion: The terminal ileum is the most common GI location for NETs. Terminal ileum intubation on coloscopy is attempted 30-80% and greatly aids in diagnosis, as with our patient. Once diagnosed, there is limited guidance on treatment of diarrhea in patients with NETs and negative carcinoid workup. There are no abstracts or research on treatment of diarrhea with negative carcinoid syndrome. One treatment for carcinoid syndrome is somatostatin analogues but no guidelines with non-carcinoid NETs and therapeutic value in octreotide. However, with our patient, treatment with monthly octreotide injections resolved their symptoms. Our case emphasizes importance of ileal intubation in coloscopy and that somatostatin analogue treatment should be considered in non carcinoid NETs.Figure 1.: Small bowel (terminal ileum): well-differentiated neuroendocrine tumor (G1).