The appendiceal lumen is engorged by inspissated eosinophilic mucin, a feature of cystic fibrosis. This can lead to a sausage-like appendix.
The wall of the appendix shows glands spewing abundant mucin which is abnormally thick. Although there is no inflammation present, the dilated appendix may still cause clinical symptoms suspicious for appendicitis. Ultrasound reveals a dilated appendix, even in the absence of appendicitis in cystic fibrosis patients, making this test less useful than in the typical patient.
The underlying glands are dilated, with prominent goblet cells.
Cystic fibrosis is due to a mutation of the cystic fibrosis transmembrane conductance regulator gene, which helps create sweat, digestive juices, and mucus. Appendiceal lesions in patients with cystic fibrosis represents a spectrum ranging from simple mucous distention, intucesseption, to acute appendicitis with perforation and abscess formation.