Appendicitis is most commonly initiated by swelling of the submucosal lymphoid tissue which blocks the appendiceal lumen. Rarely is a fecolith found. The successive compression of lymphatics, veins and finally arteries combined with overgrowth of luminal bacteria is the normal sequence of events.
The early inflammatory changes progress to suppuration and gangrene. In the normal individual, inflammatory products on the surface of the appendix cause adjacent omentum, mesentery and loops of bowel to adhere to the appendix and wall it off. These adherent structures constitute the mass that is sometimes felt. If perforation occurs, it may form an abscess if the walling off process is complete.
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