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Appendiceal Diverticulitis

      Diverticulitis has long been known to affect the right colon, and in recent years, our understanding has evolved in regard to the underlying cause. Appendiceal diverticulitis has yet to gain widespread recognition despite the fact that it was first described in 1893. Commonly dismissed by surgeons and pathologists as a variant of true appendicitis, appendiceal diverticulitis is a discrete clinical process that must be considered in the appropriate setting. We describe a case of appendiceal diverticulitis in a previously healthy 59-year-old man and review the literature.
      Appendiceal diverticular disease was first described in 1893 by Kelynack
      • Kelynack TN
      as a “greatly distended appendix, totally shut off from the cecum, having two distinct diverticular processes directed between the folds of the mesentery.” Since then, this disease process has been characterized as either congenital or acquired. The congenital form is exceedingly rare, and diverticularization involves all layers of the appendiceal wall. The acquired form, which is more prevalent, results from mucosal hemiations through a muscular defect on the mesenteric border of the appendix. Commonly dismissed by surgeons and pathologists as a variant of true appendicitis, appendiceal diverticulitis is a discrete clinical pathophysiological process that manifests differently than classic appendicitis in regard to age, onset of symptoms, operative findings, and histopathological examination.
      Appendiceal diverticulitis is identified in up to 2% of appendectomy specimens.
      • Stout AP
      A study of diverticular formation in the appendix.
      • Spriggs EI
      • Marxer OA
      Intestinal divenicula.
      • Lipton S
      • Estrin J
      • Classer L
      Diverticular disease of the appendix.
      Four morphologic subtypes have been identified based on the anatomical site of inflammation. Although specific causes are unknown, appendiceal diverticular disease is hypothesized to occur secondary to orifice obstruction; subsequent inflammation predisposes to the formation of false diverticula.
      • Skaane P
      • Strom EH
      Peridiverticnvlitis of the appendix: an unusual ultrasonic “target lesion.”.
      The congenital form is thought to be similar to diverticular disease of the colon. Treatment of symptomatic appendiceal diverticulitis is similar to that of acute appendicitis—that is, surgical resection. We describe appendiceal diverticulitis in a 59-year-old man and briefly review the literature on this uncommon condition.

      REPORT OF A CASE

      A previously healthy 59-year-old man presented to the emergency department because of an 11-day history of bandlike lower abdominal pain. The pain was progressive in severity and was associated with anorexia, constipation, persistent belching, subjective fever, and chills. Physical examination revealed a man with a toxic appearance in moderate distress with a temperature of 38.2°C. The abdomen was soft with bilateral lower quadrant tenderness, worse on the right than on the left side. Voluntary guarding was noted, but rebound could not be elicited. The leukocyte count was 12.1 × 109/L with a left shift (segmented neutro-phils, 64%; bands, 14%). Findings on plain x-ray films were nonspecific, but computed tomography revealed gross thickening of the terminal ileum and cecum with a small adjacent abscess collection (Figure 1).
      Figure thumbnail gr1
      Fig. 1Computed tomogram of abdomen showing adjacent abscess cavity (circled area).
      In light of the patient's symptoms and 11-day history of lower abdominal pain, a gastroenterologist was consulted to evaluate the possibility of Crohn disease. However, 24 hours later, the patient had peritoneal signs and was transferred to the operating room. Through a right lower quadrant incision, a “ruptured appendix” was found, but pathologic analysis demonstrated a type 1 appendiceal diverticulitis; histologically, a single appendiceal diverticulum was identified, with acute inflammation and perforation at its tip. The surrounding appendiceal mucosa was normal with no evidence of true appendicitis. The patient was treated for 5 days with broad-spectrum intravenous antibiotics, and he recovered without complications. Colonoscopy performed 6 months later showed no abnormalities. At 1-year follow-up, the patient was doing well.

      DISCUSSION

      Diverticular disease of the vermiform appendix can mimic acute appendicitis, Crohn disease, or several other pathologic conditions. Both appendiceal diverticular disease and acute appendicitis can manifest with right lower quadrant pain, fever, tenderness at McBurney point, and leukocytosis. However, appendicitis classically manifests in patients before the third decade of life, with coexistent anorexia, nausea, and emesis; often, operative intervention is necessary within 24 hours. In contrast, appendiceal diverticulitis usually appears after the third decade of life with intermittent insidious pain occurring 1 to 14 days before presentation (Table 1). Occasionally, these 2 conditions can be distinguished with a thorough history and physical examination. With detailed questioning, some patients will report prior episodes of right lower quadrant pain (ie, “chronic appendicitis”). In the literature, few gastrointestinal symptoms are demonstrated with appendiceal diverticular disease. Possible risk factors for appendiceal diverticulitis include chronic appendicitis, cystic fibrosis, age greater than 30 years, and male sex.
      • Lock J
      • Wheeler WK
      Diverticular disease of the appendix.
      • Fitzer PM
      • Rao KG
      • Bundrick TJ
      Diveniculosis of the appendix: radiographie and clinical features.
      Often, there is a delay in establishing the correct diagnosis, and perforation within the mesentery is commonly found at the time of operation.
      • Esparza AR
      • Pan CM
      Diveniculosis of the appendix.
      However, generalized peritonitis is unusual since the inflammatory process is contained within the mesoappendix by surrounding adhesions. This “masslike” effect is often mistakenly identified as carcinoma.
      • Lipton S
      • Estrin J
      • Classer L
      Diverticular disease of the appendix.
      Classically, there is a diverticulum with a cylindrical appearance, and macroscopically it may be associated with peri-appendicitis.
      • Deschenes L
      • Coulure J
      • Gameau R
      Diverticulilis of the appendix: report of sixty-one cases.
      Ultrasonography has been used to identify peridiverticulitis, but its role in detecting appendiceal diverticulitis remains to be established.
      • Skaane P
      • Strom EH
      Peridiverticnvlitis of the appendix: an unusual ultrasonic “target lesion.”.
      Surgical resection is the treatment of choice for symptomatic patients. Early operative intervention is necessary to avoid the increased morbidity and mortality associated with perforation and peritonitis.
      • Lock J
      • Wheeler WK
      Diverticular disease of the appendix.
      • BirdSong D
      • Kolachalam RB
      Laparoscopic appendectomy foi diverticular disease of the appendix.
      • Lenz TR
      Diverttculitis of the appendix: report of a case.
      A recent report described uncomplicated laparoscopic removal of the vermiform appendix with a 7-mm inflamed diverticulum.
      • BirdSong D
      • Kolachalam RB
      Laparoscopic appendectomy foi diverticular disease of the appendix.
      Laparoscopic or conventional resection of the incidentally discovered appendix with diverticulosis is indicated because two thirds of patients will experience an episode of acute inflammation. Compared with patients who have simple appendicitis, those with appendiceal diverticulitis have a higher rate of perforation and a longer convalescence.
      • Fitzer PM
      • Rao KG
      • Bundrick TJ
      Diveniculosis of the appendix: radiographie and clinical features.
      • Deschenes L
      • Coulure J
      • Gameau R
      Diverticulilis of the appendix: report of sixty-one cases.
      • Delikaris P
      • Slubbe Teglbjaerg P
      • Fisker-Sorensen P
      • Balsley L
      Diverticula of the vermiform appendix: alternatives of clinical presentation and significance.
      Once the diagnosis of appendiceal diverticular disease has been established, we recommend resection; however, some investigators doubt the potential benefit of a prophylactic appendectomy.
      • Lock J
      • Wheeler WK
      Diverticular disease of the appendix.
      • Lenz TR
      Diverttculitis of the appendix: report of a case.
      Table 1Presentation of Appendiceal Diverticulitis
      SymptomOnsetCharacteristics
      Right lower quadrant abdominal pain2-13 dInsidious, intermittent, originates in right lower quadrant
      Nausea, anorexia, emesisVariableOften absent
      FeverVariableTemperature >38.4°C
      Appendiceal diverticulitis can be classified into 1 of 4 subtypes.
      • Lipton S
      • Estrin J
      • Classer L
      Diverticular disease of the appendix.
      Type 1 is the classic form in which a normal-appearing appendix is found with an acutely inflamed diverticulum (Figure 2). Type 2 involves an acutely inflamed diverticulum with surrounding appendicitis, and type 3 is conventional appendicitis with an incidental, uninvolved diverticulum. Type 4 is an incidental appendiceal diverticulum with no evidence of appendicitis or diverticulitis.
      Figure thumbnail gr2
      Fig. 2Acute diverticulitis of the vermiform appendix (cross-section). 1, Normal-appearing appendix; 2, inflamed diverticulum; 3, mesoappendix.
      Although there are incidental reports of congenital diver-ticula (with possible linkage to a group D chromosomal trisomy 13-15),
      • Trollope ML
      • Lindenauer SM
      Diveniculosis of the appendix: a collective review.
      • Wilson RR
      Diverticula of the appendix and certain factors in their development.
      symptomatic diverticula are classically pulsion in nature. These acquired lesions occur on the mesenteric border of the appendix, often in association with an arteriolar blood vessel and thinning of the muscularis propria.
      • Skaane P
      • Strom EH
      Peridiverticnvlitis of the appendix: an unusual ultrasonic “target lesion.”.
      • Esparza AR
      • Pan CM
      Diveniculosis of the appendix.
      • Edwards HC
      Diverticula of vermiform appendix.
      Mucosa is thought to prolapse through the muscularis propria because of increased intraluminal pressure.
      • Lipton S
      • Estrin J
      • Classer L
      Diverticular disease of the appendix.
      Another hypothesis is that appendiceal diverticula are the result of residual weakness in the appendiceal wall after an episode of appendicitis.
      • Esparza AR
      • Pan CM
      Diveniculosis of the appendix.
      Microscopic examination of the appendiceal specimen often reveals a small lumen with increased thickness of the submucosa and muscular wall, as well as atrophy of the mucosal lymphoid tissue.
      • Deschenes L
      • Coulure J
      • Gameau R
      Diverticulilis of the appendix: report of sixty-one cases.
      These findings are likely physiological responses to a chronically elevated luminal pressure. As demonstrated in our case, appendiceal diverticula occur in the absence of colonie diverticulosis.
      • Trollope ML
      • Lindenauer SM
      Diveniculosis of the appendix: a collective review.
      Although treatment is similar to that for appendicitis, diverticular disease of the vermiform appendix is distinctly different and should be considered separately in the differential diagnosis of right lower quadrant pain, especially in the elderly population. Because of an insidious onset, patients with appendiceal diverticulitis seek medical treatment much later than those with classic appendicitis. Those with appendiceal diverticulitis are 4 times more likely to have a perforation, which increases mortality 30-fold compared with simple appendicitis.
      • Lipton S
      • Estrin J
      • Classer L
      Diverticular disease of the appendix.

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        Peridiverticnvlitis of the appendix: an unusual ultrasonic “target lesion.”.
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        Diverticular disease of the appendix.
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        Diveniculosis of the appendix: radiographie and clinical features.
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        Diverticulilis of the appendix: report of sixty-one cases.
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        Laparoscopic appendectomy foi diverticular disease of the appendix.
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