A 17-year-old boy was admitted to the hospital because of obstructive jaundice and weight loss.The patient had been well until two months earlier, when he consulted a physician because of pruritus. Topical antibiotic preparations were prescribed for excoriations, without improvement. Laboratory studies were performed a week later and were repeated after seven days (Table 1). An abdominal ultrasonographic examination showed distention of the gallbladder and common bile duct, with two large cysts in the left upper quadrant. Three days before admission, the patient came to this hospital.The patient had been born in the United States; his parents were Haitian immigrants. He had lost 13 kg in weight during the preceding three months, during which he had begun to run up to 1500 m daily. His stools became lighter and his urine darker several weeks before admission. He had no history of trauma, alcohol abuse, or use of illicit drugs and no risk factors for human immunodeficiency virus (HIV) infection. His parents and seven siblings were well. There was no family history of disorders suggestive of pancreaticobiliary disease.The temperature was 37°C, the pulse was 63, and the respirations were 18. The blood pressure was 120/65 mm Hg, and the weight was 74 kg.Physical examination showed no abnormalities except for excoriations and scleral icterus.Laboratory studies were performed (Tables 1 and 2). An axial T 2 -weighted image from a magnetic resonance imaging (MRI) study (Fig. 1) showed two homogeneous cysts adjacent to the tail of the pancreas. A magnetic resonance cholangiopancreatographic study (Fig. 2) showed a focal stricture in the common bile duct, which terminated at an abnormally high level; an *To convert the values for bilirubin to micromoles per liter, multiply by 17.1. †The normal range is 5 to 50 U per liter.