Introduction: Colonic diverticulosis is a common process that increases with patient age. Inflammation or infection of the diverticulum can occur causing diverticulitis. While diverticulosis is not a long-term risk factor for colorectal cancer, the short-term risk of colon cancer is markedly increased in those hospitalized for diverticulitis. Current practice patterns support completing a colonoscopy for colorectal cancer screening after acute symptoms have resolved. We report a case of goblet cell carcinoma with initial presentation as acute uncomplicated diverticulitis. Case Description/Methods: A 67-year-old man with a history of obesity was referred to the gastroenterology clinic for endoscopic evaluation after having an episode of colonic diverticulitis diagnosed by CT findings in the setting of abdominal pain. The CT also showed terminal ileitis concerning for inflammatory bowel disease. Colonoscopy to evaluate CT abnormalities in setting of abdominal pain revealed a mass-like narrowing in the ascending colon that could not be traversed with a colonoscope. Biopsy of the mass demonstrated adenocarcinoma with signet ring differentiation. He underwent a right hemicolectomy with terminal ileum excision revealing goblet cell adenocarcinoma arising from the appendix and invading the visceral peritoneum. He was initiated on palliative chemotherapy following resection. Discussion: Goblet cell carcinoma (GCC) is a rare cancer that is almost exclusively seen arising from the appendix. It is a mixed endocrine-exocrine neoplasm that is considered a low-grade malignancy unless the coexistence of adenocarcinoma is present, as seen with our patient (2). GCC is classified into three groups. Our patient would fulfill the definition of group B, adenocarcinoma ex GCC, signet ring cell type which carries a 3- and 5-year mortality rate of 15% and 64% respectively (3). Management involves resection of the primary tumor, with most cases necessitating a right hemicolectomy, given delayed presentation with colonic invasion, and intraperitoneal chemotherapy. This case represents a common presentation for an exceptionally rare cancer. We offer this case to add to the current literature regarding GCC and to educate gastroenterologists on the condition.