A 35-year-old man presents with difficulty swallowing, weight loss, and regurgitation of undigested food. A barium swallow shows a 'bird beak' appearance of the lower esophagus. What is the most likely diagnosis?

Correct Answer: B

Rationale: The correct answer is B: Achalasia. The presentation of difficulty swallowing, weight loss, regurgitation of undigested food, and 'bird beak' appearance on barium swallow are classic for achalasia. In achalasia, there is impaired relaxation of the lower esophageal sphincter and absent peristalsis in the esophagus. This leads to functional obstruction and dilation of the esophagus, causing the characteristic 'bird beak' appearance. Incorrect Choices: A: Esophageal cancer typically presents with progressive dysphagia, weight loss, and may show a mass or stricture on imaging. C: Peptic stricture is usually seen in patients with long-standing gastroesophageal reflux disease or esophagitis. Symptoms are often related to acid reflux. D: Gastroesophageal reflux disease commonly presents with heartburn, regurgitation, and chest pain. It does not typically cause weight loss or the 'bird

Correct Answer: B

Rationale: The correct answer is B: Esophageal cancer. This patient's symptoms of difficulty swallowing solids and liquids, along with unintentional weight loss, are concerning for a malignancy like esophageal cancer. The progressive nature of dysphagia and significant weight loss are red flags for cancer. Esophageal stricture (A) can cause dysphagia but typically presents with a history of chronic inflammation or injury. Achalasia (C) is characterized by dysfunction of the lower esophageal sphincter, leading to dysphagia, but it is less likely in this case due to the weight loss. Peptic ulcer disease (D) usually presents with epigastric pain and can cause weight loss, but it is less likely to cause progressive dysphagia.

Correct Answer: B

Rationale: The most likely diagnosis is B: Primary biliary cirrhosis. This condition commonly presents with fatigue, pruritus, jaundice, elevated bilirubin, and alkaline phosphatase levels in older women. Primary biliary cirrhosis is an autoimmune liver disease that leads to destruction of bile ducts. The other choices are less likely because Hepatitis C typically presents with acute symptoms, Hemochromatosis presents with iron overload symptoms, and Wilson's disease presents with copper accumulation symptoms, which do not match the patient's clinical presentation.

Correct Answer: B

Rationale: The most likely diagnosis in this case is B: Mesenteric ischemia. Given the sudden onset of severe abdominal pain in an elderly patient with atrial fibrillation, mesenteric ischemia is a crucial consideration due to the risk of thromboembolism from the heart condition leading to inadequate blood supply to the intestines. Acute pancreatitis (A) typically presents with epigastric pain radiating to the back and elevated serum amylase/lipase levels. Peptic ulcer disease (C) usually presents with a history of dyspepsia and is less likely to cause sudden severe abdominal pain. Diverticulitis (D) commonly presents with left lower quadrant pain and tenderness, which contrasts with the soft abdomen and minimal tenderness seen in this case.

Correct Answer: C

Rationale: The correct answer is C: Acute cholangitis. In a 30-year-old woman with right upper quadrant pain, fever, jaundice, elevated white blood cell count, and bilirubin levels, acute cholangitis is the most likely diagnosis. This condition is characterized by inflammation of the bile ducts, often due to obstruction, leading to symptoms such as pain, fever, and jaundice. The combination of right upper quadrant pain, fever, jaundice, and elevated white blood cell count and bilirubin levels suggests an infection in the biliary system, which is typical of acute cholangitis. Acute hepatitis (choice A) typically presents with elevated liver enzymes but may not have the same degree of biliary obstruction symptoms. Acute cholecystitis (choice B) usually presents with gallbladder inflammation and may not cause jaundice. Pancreatic cancer (choice D) typically presents with different symptoms and is less common in a