Differential Diagnosis for RUQ Pain with Fever and Leukocytosis
Single most likely diagnosis:
- Acute cholecystitis: This is the most likely diagnosis given the presentation of RUQ pain, fever, leukocytosis, a distended thin-walled gallbladder (GB) with a stone on ultrasound, and a tender RUQ mass on examination. These findings are classic for acute cholecystitis, which is inflammation of the gallbladder often caused by gallstones blocking the cystic duct.
Other Likely diagnoses:
- GB mucocele: Although less common, a GB mucocele could present similarly, especially if the gallbladder is distended and there's a concern for possible obstruction. However, the presence of a stone and the specific ultrasound findings would make acute cholecystitis more likely.
- Pancreatitis: While pancreatitis can cause RUQ pain and elevated white blood cell count, the specific findings of a distended gallbladder with a stone and a tender RUQ mass are more suggestive of gallbladder pathology rather than pancreatitis.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Acute cholangitis: Although the common bile duct (CBD) is reported as normal, and there's no jaundice, acute cholangitis is a condition that requires prompt recognition and treatment due to its high morbidity and mortality. It typically presents with jaundice, fever, and abdominal pain (Charcot's triad), but the absence of jaundice does not rule it out entirely, especially if there's a concern for a stone in the CBD not visualized on the initial ultrasound.
Rare diagnoses:
- Mirizzi's syndrome: A rare condition where a gallstone becomes impacted in the cystic duct and causes obstruction of the common bile duct, potentially leading to jaundice and cholangitis. It's less likely given the normal CBD on ultrasound but could be considered if the clinical presentation evolves.
- Gallbladder cancer: Although very rare, gallbladder cancer can present with a mass in the RUQ and systemic symptoms like fever. The presence of a stone and the specific ultrasound findings make this less likely, but it remains a consideration in the differential diagnosis, especially in older patients or those with risk factors.