The presentation of right upper quadrant (RUQ) pain, fever, and leukocytosis is classic for acute cholecystitis, which is inflammation of the gallbladder usually caused by gallstone obstruction of the cystic duct. The key surgical point is that acute cholecystitis often requires timely cholecystectomy to prevent complications such as gallbladder perforation or abscess formation. The presence of fever and leukocytosis indicates an inflammatory and infectious process localized to the gallbladder. Other options like acute pancreatitis and hepatitis typically present with different pain patterns and lab findings, while peptic ulcer disease rarely causes fever and leukocytosis.

Reference: Schwartz's Principles of Surgery, Brunicardi, 11th Edition.