Appendiceal Diverticulum as a Modifier of Inflammatory Trajectory in Acute Appendicitis: A Paired Case Contrast Supporting the Hybrid Model

Abstract

Background. Acute appendicitis is increasingly recognized as a heterogeneous disease in which severity is not solely determined by symptom duration or inflammatory burden. The hybrid model integrates time-dependent progression with divergent inflammatory pathways influenced by anatomic and host factors. The role of appendiceal diverticular disease within this framework remains incompletely defined. Case presentation. We report a hypothesis-generating paired case contrast of two female patients with histologically confirmed appendiceal diverticular disease and divergent inflammatory trajectories. One patient developed localized phlegmonous appendicitis with normal serum bilirubin levels despite prolonged symptoms. The second patient exhibited rapid progression to gangrenous diverticulitis with fibrinopurulent peritonitis within 12 hours, accompanied by early bilirubin elevation, marked neutrophil predominance, and elevated procalcitonin. Both cases lacked hepatic or hematologic confounders. Discussion. Despite similar anatomic substrates, the clinical courses differed markedly, challenging a purely time-dependent continuum model. The dissociation between C-reactive protein and bilirubin behavior suggests that bilirubin reflects systemic inflammatory response rather than localized inflammation or symptom duration alone. Conclusion. This paired case contrast supports the hybrid model of acute appendicitis and suggests that appendiceal diverticulum may function as a conditional modifier of inflammatory trajectory. Serum bilirubin appears to reflect systemic response patterns rather than local pathology.