Histological features of resolving acute, non-complicated phlegmonous appendicitis

Area of Science:

• Pathology
• Gastroenterology
• Surgical Pathology

Background:

• Acute appendicitis is a common surgical emergency.
• Understanding the histological spectrum of appendicitis aids in diagnosis and management.
• The features of resolving appendicitis require further characterization.

Purpose of the Study:

• To describe the histological features of resolving acute appendicitis.
• To identify specific cellular infiltrates associated with the regression phase.
• To correlate histological findings with clinical symptom duration.

Main Methods:

• Review of 200 formalin-fixed, paraffin-embedded appendices from non-complicated acute phlegmonous appendicitis cases.
• Histological analysis focusing on cellular infiltrate patterns (lymphocytic, eosinophilic) and presence of granulation tissue.
• Classification of cases into three groups based on histological findings and statistical analysis of clinical symptom duration.

Main Results:

• A predominantly lymphocytic infiltrate in the subserosa and/or muscularis propria was observed in 80 out of 200 cases.
• A mixed infiltrate of lymphocytes and eosinophils was noted in the muscularis propria, with a lesser degree of infiltration compared to classic appendicitis.
• Cases with lymphocytic infiltrate (Group 2) and granulation tissue (Group 3) showed statistically significant differences in mean symptom duration compared to classic phlegmonous appendicitis (Group 1).

Conclusions:

• A mixed infiltrate of lymphocytes and eosinophils represents a regression phase of acute appendicitis.
• Histological patterns can indicate different stages of appendicitis resolution.
• Further research into the inflammatory and reparative processes in appendicitis is warranted.