Appendiceal diverticular diseases are typically

Appendiceal diverticular diseases are typically classified into 4 main subtypes. Type 1 is diverticulitis with a normal appendix; Type 2 is diverticulitis with appendicitis; Type 3 is a noninflamed diverticulum with appendicitis; and Type 4 is a noninflamed diverticulum with a normal appendix. Type 1 is the most common of the four types. However, among the 10 patients examined in this arecoline hydrobromide study, 8 patients had Type 2, only one patient had Type 1, and one patient had Type 4. In two of the eight patients with Type 2, a few neutrophils were identified in the muscularis propria adjacent to the acute inflammatory diverticulum. Thus, Type 2 may represent late-stage Type 1 or Type 3. Patients with Type 2 appendiceal diverticulitis were frequently symptomatic, which may increase the risk of perforation. Three studies have indicated that appendiceal neoplasia is significantly associated with diverticular disease. In a 23-case series reported by Dupre et al in 2008, 11 (48%) patients with acquired diverticulosis also exhibited primary appendiceal neoplasia, which included five well-differentiated neuroendocrine tumors (i.e., carcinoids), three mucinous adenomas, one tubular adenoma, and two adenocarcinomas. In 1998, Medlicott and Urbanski reported that 29% (9/31) of patients with acquired diverticulosis also had primary appendiceal epithelial neoplasia (7 adenomas and 2 goblet cell carcinoids). Lamps found that 42% (8/19) appendiceal low-grade mucinous neoplasms were associated with appendiceal diverticula. In our case series of 10 patients, three patients had mucoceles, one patient had a small hyperplastic polyp, and two patients had epithelial regenerative atypia and small foci of adenomatous change with mild dysplasia. Appendiceal diverticulosis is typically asymptomatic. The mechanism of symptomatic appendiceal diverticulosis is unknown. Appendiceal diverticulitis is generally caused by partial or complete obstruction of the appendiceal lumen. Right lower quadrant abdominal pain subsequently develops. Distinguishing appendiceal diverticulitis from acute appendicitis is difficult; however, several differences have been observed. Compared to the symptoms of appendicitis, symptomatic appendiceal diverticulitis has a longer duration of pain (1–14 days); primarily develops in older adults (older than 30 years); has a lower frequency of accompanying abdominal pain, nausea, and vomiting; and has a greater occurrence of right lower quadrant abdominal pain.Table 5 lists the differences between the clinical manifestations of typical acute appendicitis and appendiceal diverticulitis. Image studies may facilitate preoperative diagnosis. Place reported the findings of an abdominal CT scan in a patient with appendiceal diverticulitis. The scan showed a large pericecal phlegmon. However, CT image findings (e.g., appendiceal swelling, pericecal inflammation, abscess, phlegmon, and increased pericecal fat density) did not sufficiently distinguish appendiceal diverticulitis from cecal diverticulitis or appendicitis. Kubota et al reported a patient who was diagnosed preoperatively by an abdominal ultrasound, which showed an enlarged, swollen appendix with a cross-section diameter of 10 mm and multiple small hypoechoic lateral pouchlike projections. In the future, high-resolution ultrasound or CT scans may facilitate the preoperative diagnosis of appendiceal diverticulosis. Appendiceal diverticulosis may also be identified by surgeons during an operation if the distal portion of the specimen is longitudinally bisected along the long axis and the mesoappendiceal plane. We recommend that a frozen section study should be performed for suspected cases of appendiceal diverticulosis. However, most cases were incidentally identified during pathological examinations. Careful inspection and obtaining a greater number of serial sections are recommended when lesions are observed; this may enable identification of additional diverticula, perforation, or neoplasms.