Plastron Appendicitis Mimicking a Malignant Adnexal Mass

Plastron appendicitis is a rare complication of acute appendicitis, characterized by localized and encapsulated inflammation within the surrounding tissues. It accounts for ∼4%–5% of all acute appendicitis cases. The mass-like appearance of plastron appendicitis can mimic various malignant pathologies, particularly those of the adnexal region. Due to its rarity, diagnosing plastron appendicitis can be challenging. Advanced imaging techniques, such as 18 F-FDG PET/CT, are crucial in differentiating it from other pathologies. In this case presentation, we aim to present the 18 F-FDG PET/CT and contrast-enhanced CT imaging findings of a patient with plastron appendicitis, which was initially suspected to be a malignant adnexal mass.