Incidental serrated lesions of the appendix: analysis of 2,137 appendectomy specimens

Serrated lesions of the appendix are rare, often incidental findings in routine appendectomy specimens. Their true frequency, histopathologic spectrum, and anatomic distribution remain incompletely characterized, partly due to variability in sampling practices.

We retrospectively reviewed 2,137 appendectomy specimens (2015-2025) from a single tertiary pathology center. Cases with histologically confirmed serrated lesions were reexamined, classified as hyperplastic polyp (HP) or sessile serrated lesion/polyp (SSL/P), and assessed for clinicopathologic parameters including lesion size, location, and associated pathologies. Nonparametric tests were used, with statistical significance defined as p < .05.

Serrated lesions were identified in 34 cases (1.6%) with 36 serrated lesions, comprising 17 HPs (0.8%) and 19 SSL/Ps (0.9%). SSL/Ps were significantly larger than HPs (median 10.0 vs. 2.7 mm, p < .001) and were more frequently located in the distal appendix (68.4% vs. 33.3%, p = .045, one-tailed Fisher's exact test). No dysplasia or traditional serrated adenoma was detected. Acute appendicitis was present in 88% of cases, and associated neoplasms in 9%.

Appendiceal serrated lesions are uncommon and often incidental. In this large appendectomy series, SSL/Ps differed from HPs by larger size and distal predilection. These findings primarily support diagnostic awareness and optimized sampling/grossing practices-particularly careful evaluation of the distal appendix-rather than clinical risk stratification. Further studies incorporating systematic clinical correlation and molecular/immunohistochemistry analyses are warranted.