S1737 Goblet Cell Adenocarcinoma: A Rare and Aggressive Appendiceal Neoplasm

Abstract

Introduction: Goblet cell adenocarcinoma (GCA) is a rare and unique appendiceal neoplasm, containing features of both adenocarcinoma and neuroendocrine tumors (NETs). Also termed "goblet cell carcinoids" and previously considered a low-grade malignancy, these tumors are now known to be much more aggressive than traditional carcinoid tumors due to coexistence of high grade adenocarcinoma. In fact, up to 40% of cases present after development of distant metastasis, most commonly to the peritoneum. This has led to pressure for updated nomenclature removing the term "carcinoid" to prevent confusion and potential for incorrect management. Case Description/Methods: A 69-year-old Filipino male with minimal past medical history presented with a four day history of sharp, bloating-type abdominal pain and difficulty passing gas. He denied any other symptoms, specifically nausea, vomiting, constipation or diarrhea. Screening colonoscopy performed 3 years prior with intubation of the terminal ileum was normal. CT of the abdomen/pelvis demonstrated a small bowel obstruction due to a mass, appearing to arise from the terminal ileum, encompassing the cecum and appendix. Colonoscopy was requested, however after discussion with colorectal surgery service, the decision was made to proceed directly to surgical resection, given likelihood of malignancy. Pathology revealed goblet cell adenocarcinoma with peritoneal metastasis, consistent with stage 4B (T4b N2 M1b). Discussion: Goblet cell adenocarcinomas are more aggressive and have a worse prognosis than NETs. Therefore, they must be staged and treated as appendiceal carcinomas. The mixed histology of these tumors, has led to misdiagnosis and poor outcomes. Given the rapid spread of these tumors, a recent normal screening colonoscopy should not preclude prompt investigation of abdominal symptoms in at-risk patients, to include cross-sectional imaging, because surgical resection remains the primary curative treatment strategy. Furthermore, if suspected, preoperative colonoscopy for biopsy should not delay surgical resection. Current debate exists regarding extent of surgical resection required for Stage 1-2 GCAs. Additional treatment strategies for Stage 3-4 GCAs include 5-fluorouracil based adjuvant chemotherapy and hyperthermic intraperitoneal chemotherapy (HIPEC). The low five-year survival, 57% for Stage 3 and 19% for Stage 4, emphasize the importance of early diagnosis and treatment.Figure 1.: A. CT abdomen/pelvis without contrast demonstrating a diffusely dilated, air-filled gastrointestinal tract extending from the stomach through the rectosigmoid colon. No transition point or obstruction noted. B. CT abdomen/pelvis with rectal contrast demonstrating an interposition of the hepatic flexure of the colon posterior and medial to the right lobe of the liver. No evidence of obstruction or strangulation noted. C. Endoscopy demonstrating a twisted, almost volvulus-like appearance at the splenic flexure, though without clear transition points.