Chronic Calculous Cholecystitis

Comments:
Rokitansky-Aschoff (RA) Sinuses: They are herniations of gallbladder mucosa into or even through the smooth muscle layer. The glands are usually oriented perpendicular to the lumen. They are gallbladder counterparts of intestinal diverticula. They usually form in response to increased intraluminal pressure due to bile outflow obstruction caused by gallstones. The presence of RA sinuses does not equate to chronic cholecystitis. They are also found in patients with biliary dyskinesia.

This image shows mucosal glands (RA sinuses) deep within the muscularis with no apparent connection to the surface. Given their location and the presence of fibrosis around glands in some cases, they may be mistaken for invasive adenocarcinoma.