Management of Appendiceal Inflammatory Mass: Nonoperative Treatment,Malignancy Risk,and Surveillance

Abstract

Background

The management of an appendiceal inflammatory mass (historically termed “plastron”) is controversial due to debates over optimal treatment strategies and malignancy risk. This 15-year retrospective study compares medical vs surgical outcomes, provides granular malignancy data, and aims to establish a risk-stratified surveillance protocol.

Material and Methods

This STROBE-compliant retrospective study analyzed 79 consecutive patients (2009-2024) with radiologically confirmed appendiceal inflammatory masses at University of Health Sciences, Ümraniye Training and Research Hospital. We performed propensity score-adjusted comparisons between medical (antibiotics ± percutaneous drainage, n = 32) and surgical (n = 47) groups. Outcomes focused on success rates, complications, hospital stay, malignancy (histopathology), and colonoscopic findings.

Results

Medical management was initially successful (68.7%, 22/32), resulting in significantly shorter hospitalization (mean difference 2.8 days, 95% CI: 0.2—5.4, 4.1 ± 2.7 vs 6.9 ± 4.8 days, P = 0.03) and fewer complications (OR 0.35, 95% CI: 0.1—0.9, 9.3% vs 23.4%, P = 0.04) vs surgery. Interval appendectomy was required in 31.2% (10/32) of medical patients. Malignancies were identified in 15.1% overall (95% CI: 7.9%—24.9%), including 6.2% diagnosed only at interval appendectomy. Colonoscopy was performed in 31.6% (25/79) and detected significant neoplasia in 20.0% (5/25; 95% CI: 8.9%–39.1%), predominantly among clinically high-risk patients.

Conclusion

Conservative management is effective, but the substantial malignancy risk (15.1%) and high colonoscopy yield (19%) in this high-risk tertiary cohort necessitate vigilant surveillance. Consistent with updated screening guidance, we recommend colonoscopic evaluation for patients aged ≥45 and/or those with elevated tumor markers or suspicious imaging, and a lower threshold for interval appendectomy in high-risk phenotypes, supporting a risk-stratified approach.