Are We Missing Tumors When Using Antibiotics Alone for Appendicitis?

The risk of missing aggressive appendiceal tumors in patients with acute appendicitis treated with antibiotics only was very low, a retrospective cohort study suggested.

Among 2,293 appendectomies, 1.6% had malignant or premalignant lesions, most commonly small and low-grade neuroendocrine tumors (NETs), reported Maxime K. Collard, MD, PhD, of Hôpital Saint Antoine and Sorbonne Université in Paris, and colleagues in JAMA Surgery.

A key concern with nonoperative management of appendicitis is the delayed diagnosis of incidental appendiceal neoplasms, the authors noted. However, clinically significant lesions that required a change in management were rare — just 0.13% of those cases eligible for antibiotic-only treatment, “and these cases remained treatable with subsequent surgical intervention.”

The overall tumor prevalence observed in the study was comparable to the reported rates of 1% to 2%, and the predominance of NETs is consistent with prior literature, the authors pointed out.

“Aggressive malignancies were rare and occurred in patients with high-risk preoperative profiles and could be effectively excluded [from antibiotic-only management] using an ensemble of simple preoperative selection criteria,” Collard and team concluded.

High-risk preoperative features included ages 60 and older, symptoms for 14 days or longer, appendiceal diameter of 15 mm or greater on imaging, complicated appendicitis on imaging, or metastatic-appearing lesions.

“Our data are reassuring for the safety of antibiotic-only treatment in strictly selected cases,” the authors wrote. “When all criteria were applied simultaneously, no aggressive malignancy met eligibility; only [grade 1] NETs smaller than 2 cm and low-grade dysplasia did, both with excellent prognosis, indicating minimal oncologic risk with rigorous selection.”

However, in an accompanying commentary, Marja A. Boermeester, MD, PhD, of the University of Amsterdam, and colleagues cautioned that the oncologic consequences of no surgical treatment for small NETs “is unclear.”

They noted that even though the malignant potential of these NETs is generally low, all the detected lesions in this study would require resection according to current standards. Thus, “while these low incidences support the overall oncologic safety of nonoperative treatment of appendicitis, caution remains warranted,” they wrote.

They also suggested that structured clinical follow-up is essential, as delayed appendectomy may be needed if symptoms from low-grade appendiceal NETs recur or persist.

This study was conducted from January 2013 through December 2021 at a tertiary surgical emergency center in Paris and included 2,293 appendectomies. The median age of the cohort was 32 years, and 44% were women.

Other lesions detected included five low-grade appendiceal mucinous neoplasms, three metastatic tumors, two goblet cell carcinomas, one mucinous adenocarcinoma, and four low-grade dysplastic polyps.

Collard and colleagues found that their proposed eligibility criteria (abdominal pain duration <14 days, age <60 years, uncomplicated appendicitis, appendiceal diameter <15 mm, and absence of suspicious appendiceal, peritoneal, hepatic, or bone lesions) would have excluded all malignant appendiceal tumors from antibiotic-only management, with the exception of 17 small grade 1 NETs and one low-grade dysplastic polyp.

When considering all selection criteria for potential antibiotic-only management, 74% of the cohort would have been eligible. Within the subgroup with uncomplicated appendicitis, 85% would have been eligible.

Collard and colleagues acknowledged that their study was limited by its retrospective, single-center design, as well as the fact that the low number of malignant or premalignant tumors detected in the study precluded the external validation of their proposed selection criteria for antibiotic-only management.