A 28-year-old woman presents with abdominal pain, diarrhea, and weight loss. She has a history of recurrent mouth ulcers and a perianal fistula. What is the most likely diagnosis?

Correct Answer: C

Rationale: The most likely diagnosis for the 28-year-old woman with abdominal pain, diarrhea, weight loss, mouth ulcers, and perianal fistula is Crohn's disease. Crohn's disease is characterized by inflammation that can occur anywhere in the digestive tract, leading to symptoms like abdominal pain, diarrhea, weight loss, mouth ulcers, and fistulas. Ulcerative colitis primarily affects the colon, not the entire digestive tract like in this case. Irritable bowel syndrome typically presents with abdominal pain and changes in bowel habits but not with fistulas. Diverticulitis is inflammation of pouches that can develop in the colon, but it does not typically present with mouth ulcers or fistulas.

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

Correct Answer: A

Rationale: The most likely diagnosis for a 50-year-old man with jaundice, dark urine, pruritus, and a mass in the head of the pancreas is pancreatic cancer. Pancreatic cancer commonly presents with obstructive jaundice due to compression of the common bile duct by the tumor in the head of the pancreas. This leads to dark urine (due to increased bilirubin) and pruritus. Chronic pancreatitis typically presents with recurrent abdominal pain, not progressive jaundice. Gallstones can cause obstructive jaundice but are not associated with a mass in the pancreas. Primary sclerosing cholangitis presents with jaundice, but it typically involves intrahepatic and extrahepatic bile ducts, not the pancreas.