A Perf-ect Diagnosis: Ileocolonic Crohn Disease Presenting as Acute Appendicitis

Abstract

Background: Crohn disease (CD) involving the appendix is rare, but often presents as lower abdominal pain. Occasionally patients may present with symptoms mimicking acute appendicitis. A retrospective review from 2014 cited an overall incidence of CD at the time of appendectomy for acute appendicitis to be only 0.55% Case: An 18-year-old male without known past medical history presented with intermittent right lower quadrant abdominal pain for 3 weeks. CT scan revealed acute appendicitis with possible early perforation and he was treated non-operatively with antibiotics. A repeat CT scan 16 days later demonstrated bowel wall thickening of the distal ileum, proximal right colon, and appendix. At the surgical follow up visit he admitted to a long-standing history of 5-6 loose bowel movements per day and he was referred to gastroenterology. He soon returned to the hospital with recurrent abdominal pain and fever. CT scan demonstrated persistent inflammation in these areas. Colonoscopy revealed an edematous ileocecal valve and a narrowed, inflamed cecal lumen with ulcerations. Biopsies demonstrated features suggestive of CD, but no granulomas. Fecal calprotectin was elevated to 212 mcg/g. He was discharged with a steroid taper, but returned to the office with a complaint of right groin pain and on exam had a positive psoas sign. MRE demonstrated a right psoas abscess and continued inflammation in the terminal ileum and cecum and he was re-admitted for percutaneous drainage and IV antibiotics. Two weeks later he underwent open ileocecectomy and pathology confirmed the diagnosis of CD. Discussion:The overall incidence of CD involving the appendix is low, with a 2001 study citing appendiceal involvement in only 0.2% of patients with CD. Isolated appendiceal CD is even rarer with only 229 cases reported in the literature, and prognosis appears to be better with post-appendectomy recurrence rates of only 0-10%. Conversely, appendectomy in patients with CD with ileocecal involvement has a high rate of fistula formation. There has been recent inconsistent literature regarding a proposed increased risk of developing CD following appendectomy, but this is felt to be largely due to diagnostic bias. Overall, this case highlights the importance of keeping an initial broad differential, taking an adequate history, and having a high index of suspicion when working up a case of suspected appendicitis, especially with atypical symptoms or a prolonged course.