1905 Appendiceal Neuroendocrine Tumor in an Inverted Appendix Discovered on Screening Colonoscopy

Abstract

INTRODUCTION: Appendiceal carcinoid tumors are the most common appendix neoplasm. Most cases are diagnosed incidentally after an appendectomy. We present a rare case of neuroendocrine neoplasm from an inverted appendix manifesting as cecal polyp seen on a screening colonoscopy. CASE DESCRIPTION/METHODS: Patient is a 58-year-old female with no significant past medical history or family history of colon cancer who presented for colorectal cancer screening. She denied any fevers, night sweats, flushing, palpitations, weight loss, abdominal pain, or changes in bowel habits. She denied any prior abdominal surgeries. Patient underwent colonoscopy which revealed internal hemorrhoid, two polypoid lesions in the cecal area measuring 8 mm, and 1.3 cm. A total of 6 mL of normal saline was injected underneath to lift them up and snaring polypectomy technique applied. Endo Clip was applied at the base of the large polyp and the specimen was retrieved and sent to the pathology. Pathology revealed well-differentiated neuroendocrine tumor, grade 1, 0.4 cm, involving submucosa and muscularis propria of probable inverted appendix/appendiceal stump. IHC stains for CDX 2, Pankeratin, Chromogranin, and Synaptophysin were positive. Stains for CK7/CK 20/PAX 8/Vimentin were negative. Patient returned for a follow-up office visit and was doing well after the procedure. She was later referred for a CT abdomen pelvis with contrast which failed to show an appendix, any cecal masses, or other acute intra-abdominal pathologies. Patient was then referred to a general surgeon for further evaluation who recommended a one-year surveillance colonoscopy. DISCUSSION: Neuroendocrine tumors are the most common tumor of the appendix. They are typically discovered incidentally from an appendectomy but rarely manifest in an inverted appendix. Additionally, they are usually located in the distal 1/3 of the appendix and for that reason most patients do not present with obstructive symptoms. Management of tumor depends on the size of the tumor. If the carcinoid is < 2 cm, appendectomy is generally sufficient. In this case the tumor was only 0.4 cm and was completely excised endoscopically in the inverted appendix.