Neutrophils are seen infiltrating the mucosa and submucosa of the gallbladder in this patient with acute cholecystitis. Bouts of acute cholecystitis are marked by right upper quadrant colicky pain. Gallstones are typically present, often obstructing the neck of the gallbladder or cystic duct. "Acalculous" cholecystitis (no stones present) is much less common.

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