Impacted viable cholesterol polyp: A rare etiology of acute cholecystitis

What is it about?

Acute cholecystitis is generally caused by the incarceration of a gallstone. Herein, this case report presents an extremely rare case of acute cholecystitis caused by an impacted viable cholesterol polyp, which appeared as a strongly hyperechoic lesion with a faint acoustic shadow. However, macroscopic examination of the resected specimen revealed two small cholesterol polyps impacted at the gallbladder neck. Histopathologically, these polyps showed no evidence of tissue degeneration or necrosis. FIGURE: The fresh specimen incised along the longitudinal axis on the peritoneal side: Macroscopically, the resected gallbladder reveals a mildly thickened wall with cholesterosis, reddened mucosa, and three polyps. One polyp is located in the gallbladder body (arrowhead), while the other two are detached from the mucosa and situated at the sites marked with two circles.

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Photo by Boris Smokrovic on Unsplash

Photo by Boris Smokrovic on Unsplash

Why is it important?

Typically, cholesterol polyps are connected to the gallbladder mucosa by a fine filamentous stalk. They are reported to disappear or decrease in size occasionally without symptoms. This process is usually attributed to detachment and subsequent devascularization, leading to degenerative changes and tissue necrosis. The authors similarly experienced a few cases in which a cholesterol polyp, 10 mm in diameter, disappeared asymptomatically. It is hypothesized that acute cholecystitis could be caused by a viable cholesterol polyp that arises only under specific circumstances. In this case, the cholesterol polyps originated in the gallbladder neck and became impacted in situ, leading to acute cholecystitis before any histopathologically degenerative changes could have occurred. The operative maneuvers likely detached the polyps from the gallbladder mucosa. However, it remains unclear whether detachment of the polyps occurred before surgery or because of operative manipulation. Unfortunately, the mechanism underlying the faint acoustic shadow cannot be determined because the sonographic appearance of a cholesterol polyp immediately after detachment from the gallbladder mucosa has not been well documented.

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