Double mimickry: perforated sigmoid colon cancer presenting as acute appendicitis in a 34 year-old woman.

Alejandro Rodriguez-Garcia, MD, Roberto Alatorre-Adame, MD, Roman Gonzalez-Ruvalcaba, MD, Eduardo Flores-Villalba, MD. Tecnologico de Monterrey

INTRODUCTION Colon cancer may present in a number of ways, often times mimicking acute diverticulitis, with or without formation of an intra-abdominal abscess.

CASE REPORT: We report the case of a previously healthy 34 year old female who presented to the ER complaining of abdominal pain in the RLQ. Upon examination the patient was tachycardic and febrile. Tenderness was noted in the right lower quadrant, along with resistance in the right iliac fossa. A CBC showed left shift, and ultrasound was compatible with acute appendicitis. The patient was taken to the OR for laparoscopic appendectomy. Upon laparoscopy, free liquid was noted in the abdomen. The appendix was grossly normal. An inflammatory process was noted in the left lower quadrant. The patient was deemed to have acute diverticulitis and underwent appendectomy with peritoneal lavage. A drain was placed in the LLQ. After an uneventful recovery, colonoscopy was performed at 1month post-op. A large mass was noted in the sigmoid colon; biopsy confirmed a tubule-villous dysplastic lesion. Following this, laparoscopic left colectomy was performed. Pathology showed stage IIIB adenocarcinoma. No K-ras mutation was found. The patient is well at 3 year follow-up.

DISCUSSION: Although cancer of the sigmoid colon may mimick acute diverticulitis, it is rare for it to cause right-sided pain. In this case, the patient was incorrectly thought to have diverticular disease after observing normal appendix. Follow-up colonoscopy was key in ascertaining the correct diagnosis.