CT can designate when to alter acute appendicitis surgical management

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By using CT to visualize indications of coexisting mucoceles in patients with acute appendicitis, surgical management may have to be altered, according to a study published in the March issue of the American Journal of Roentgenology.

In patients with acute appendicitis, a mucocele--a cystic mass resulting from a dilated appendiceal lumen caused by an abnormal accumulation of mucus--can become inflamed, and the clinical and CT findings can mimic those of acute appendicitis without mucocele.

"It is important to identify mucocele preoperatively because the surgical approach may have to be altered to avoid rupture of the mucocele and resultant pseudomyxoma peritonei. In addition, more extensive surgical resection may be needed if a neoplastic cause of a mucocele is identified," the authors wrote.

Researchers from the department of radiology at New York University Medical Center in New York City sought to identify the CT features of mucocele of the appendix in association with acute appendicitis and to determine whether this entity can be differentiated from acute appendicitis without mucocele.

Two readers retrospectively interpreted the CT scans of 70 patients (12 with acute appendicitis with mucocele, 29 with acute appendicitis without mucocele, 29 with a normal appendix). The appendix was evaluated for maximal luminal diameter, cystic dilatation, luminal attenuation, appendicolith, mural calcification and enhancement, periappendiceal fat stranding, fluid and lymphadenopathy. 

The results showed that cystic dilatation of the appendix and maximal luminal diameter achieved statistical significance for the diagnosis of acute appendicitis with mucocele. Mural calcification achieved statistical significance for one reader and a statistical trend for the other. A maximal luminal diameter greater than 1.3 cm had a sensitivity of 71.4 percent, specificity of 94.6 percent and overall diagnostic accuracy of 88.2 percent for the diagnosis of acute appendicitis with mucocele.

"Although there is overlap with acute appendicitis without mucocele, we conclude that CT features suggestive of a mucocele coexisting with acute appendicitis include cystic dilatation of the appendix, mural calcification, and a luminal diameter greater than 1.3 centimeters," the authors noted. "If these features are visualized in a patient with acute appendicitis, the surgeon should be alerted to the possibility of coexisting mucocele because surgical management may have to be altered."

The authors noted that an important limitation of the study was the small number of patients with mucocele, which limited the statistical power of comparisons between patients with mucocele and those without.

"However, acute appendicitis with associated mucocele is a rare condition, and a multicenter study would be needed to collect a large number of cases," they wrote.