Mucinous adenocarcinoma of the appendix invading in the sigmoid colon: Case report

Introduction: Mucinous appendiceal adenocarcinoma (MAA) is a rare malignancy that can occasionally present with complications such as rupture and local invasion. This report details a unique case of MAA rupturing into the sigmoid colon and the subsequent management of the patient. Case presentation: A 62-year-old male presented with hypogastric abdominal pain, diarrhea, fever, and a palpable abdominal mass. A CT scan revealed an 8 cm intraperitoneal collection in contact with both the appendix and the sigmoid colon, suggesting acute appendicitis complicated by an abscess. An emergency laparotomy was performed, revealing an abscess involving both organs. An en-bloc resection of the appendix and the sigmoid colon was performed, followed by a Hartmann procedure. Histopathological analysis confirmed mucinous cystadenocarcinoma of the appendix invading the sigmoid colon, with clear resection margins and no lymph node involvement (pT4b). After a normal postoperative CT scan and colonoscopy, the patient underwent a right hemicolectomy and restoration of digestive continuity, with no residual tumor found. Discussion: MAA is an uncommon malignancy, and its rupture into the sigmoid colon is exceedingly rare. This case highlights the importance of prompt surgical intervention in managing complications such as abscess formation and tumor invasion. The en-bloc resection and Hartmann procedure were effective in removing the diseased tissues, and subsequent follow-up with right hemicolectomy confirmed no further tumor spread. Conclusion: This case demonstrates the successful management of mucinous appendiceal adenocarcinoma rupturing into the sigmoid colon through timely surgical intervention. This case underscores the importance of early diagnosis and aggressive treatment in achieving positive outcomes for rare malignancies.