Risk of appendiceal malignancy in conservatively treated acute appendicitis.

Background and aims: Appendectomy has historically been the standard treatment of acute appendicitis, but lately, conservative treatment of uncomplicated acute appendicitis with antibiotics has successfully been used in selected patients. Complicated acute appendicitis is often treated conservatively initially, but may benefit from interval appendectomy due to the higher risk of appendiceal malignancy and recurrence. Recommendations for follow-up after conservatively treated appendicitis vary. Furthermore, the risk of underlying malignancy and the necessity of routine interval appendectomy are unclear. This study aims to evaluate follow-up status, recurrence, and underlying appendiceal malignancy in conservatively treated uncomplicated and complicated acute appendicitis.

Methods: This study included patients with conservatively treated acute appendicitis at Skåne University Hospital, Sweden during 2012-2019. Information on patient demographics at index admission and data on follow-up, recurrence, number of appendectomies after initial conservative treatment, and underlying malignancy were retrieved from medical charts.

Results: The study cohort included 391 patients, 152 with uncomplicated and 239 with complicated acute appendicitis. Median time of study follow-up was 52 months. The recurrence risk was 23 (15.1%) after uncomplicated and 58 (24.3%) after complicated acute appendicitis (p = 0.030). During follow-up, 55 (23%) patients with complicated acute appendicitis underwent appendectomy. Appendiceal malignancies were found in 12 (5%) patients with previous complicated acute appendicitis versus no appendiceal malignancies after uncomplicated acute appendicitis (p = 0.002).

Conclusion: The risk of appendiceal malignancy and recurrent appendicitis was significantly higher in patients with complicated acute appendicitis compared with uncomplicated acute appendicitis.