Interval appendicitis features: Potential mimickers of other conditions
Patients with perforated appendicitis are often managed with antibiotic therapy followed by a delayed appendectomy. Histologic features of appendectomy specimens have been incompletely described, especially in the recent literature. The authors of this study described the histomorphology of interval appendicitis, focusing on the features that could mimic important conditions, such as infections, Crohn disease, and mucinous neoplasms. They systematically evaluated histologic findings from 100 interval appendectomy specimens, documenting the nature and distribution of residual inflammation, architectural alterations of the appendix, and epithelial changes in the mucosa. Fifty-four of the 100 patients had radiologic evidence of appendiceal perforation, and 97 were treated with intravenous or oral antibiotic therapy, or both, prior to appendectomy. Percutaneous drains were placed in 34 patients. Common histologic findings included mural eosinophilic infiltration (54 percent), periappendiceal fibrosis (54 percent), and xanthogranulomatous inflammation (31 percent). Periappendiceal fibrosis was frequent among patients with radiologic evidence of perforation. Nine cases featured pulse granulomata associated with fecal material. Epithelioid granulomata were detected in six cases and confined to mucosal lymphoid follicles in all of them. Only four of these cases were accompanied by mural lymphoid aggregates that raised the possibility of Crohn disease. Changes mimicking mucinous neoplasms were more common: 14 cases displayed goblet cell hyperplasia, 15 contained diverticula, and 16 showed mural or periappendiceal mucin pools. The authors concluded that although interval appendectomy specimens occasionally contain inflammatory infiltrates that mimic infections or Crohn disease, or both, changes that can be confused with mucinous neoplasms are more frequently encountered.
Mostyka M, Yantiss RK, Chen Z, et al. Interval appendectomy specimens: potential mimickers of important inflammatory and neoplastic conditions. Arch Pathol Lab Med. 2023;147(5):546–551.
Correspondence: Dr. Maria Mostyka at [email protected]