A 55-year-old man presents with jaundice, pruritus, and dark urine. Laboratory tests reveal elevated bilirubin and alkaline phosphatase. Imaging shows dilated intrahepatic bile ducts and a normal common bile duct. What is the most likely diagnosis?

Correct Answer: A

Rationale: The most likely diagnosis is Primary biliary cirrhosis (PBC). PBC typically presents with jaundice, pruritus, and dark urine due to impaired bile flow. Elevated bilirubin and alkaline phosphatase levels are common in PBC. Imaging findings of dilated intrahepatic bile ducts and a normal common bile duct support the diagnosis of PBC. Primary sclerosing cholangitis (Choice B) would show strictures and beading of bile ducts on imaging. Gallstones (Choice C) would typically present with a common bile duct obstruction. Pancreatic cancer (Choice D) may present with similar symptoms but is less likely given the specific imaging findings in this case.

Correct Answer: B

Rationale: The correct answer is B: Celiac disease. The patient's symptoms of abdominal pain, bloating, diarrhea, and improvement with fasting are classic for celiac disease, an autoimmune condition triggered by gluten ingestion. Her iron deficiency anemia can be attributed to malabsorption common in celiac disease. Irritable bowel syndrome (A) typically presents with abdominal pain relieved by defecation, not fasting. Lactose intolerance (C) results in symptoms after consuming dairy, not necessarily improved by fasting. Crohn's disease (D) may present similarly, but the improvement with fasting and iron deficiency anemia point more towards celiac disease in this case.

Correct Answer: B

Rationale: The correct answer is B: Hemochromatosis. In this case, the patient's symptoms of fatigue, arthralgia, darkening of the skin, elevated liver enzymes, and high serum ferritin levels point towards iron overload disorder. Hemochromatosis is a genetic condition characterized by excessive absorption and accumulation of iron in various organs, leading to liver damage and skin pigmentation. Wilson's disease (A) presents with copper accumulation, not iron. Alpha-1 antitrypsin deficiency (C) primarily affects the lungs and liver, not causing iron overload. Autoimmune hepatitis (D) does not typically present with elevated ferritin levels.

Correct Answer: B

Rationale: The correct answer is B: Hyperthyroidism. In this case, the low TSH and high free T4 levels indicate overproduction of thyroid hormones, leading to symptoms like fatigue, weight gain, and constipation. Low TSH is a result of negative feedback due to high T4 levels. Hyperthyroidism is characterized by an overactive thyroid gland, resulting in excess thyroid hormone production. Other choices are incorrect because hypothyroidism would show high TSH levels, thyroiditis typically presents with thyroid tenderness and inflammation, and thyroid cancer usually does not cause these hormonal imbalances.

Correct Answer: A

Rationale: The correct answer is A: Ulcerative colitis. This chronic inflammatory condition affects the colon and rectum, leading to symptoms like abdominal pain, diarrhea, and rectal bleeding. The patient's recurrent episodes and history of similar symptoms point towards ulcerative colitis. Irritable bowel syndrome (choice B) typically presents with abdominal pain, bloating, and changes in bowel habits but not rectal bleeding. Celiac disease (choice C) presents with gastrointestinal symptoms after consuming gluten. Diverticulitis (choice D) presents with localized abdominal pain and fever due to inflammation or infection of the diverticula, not typically with rectal bleeding.