Bile duct adenoma 2症例の画像及び病理学的検討―造影US門脈相washout所見に注目して―

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Ultrasound (US) revealed a 6-mm hypoechoic nodule in segment 6 of a 65-year-old man with alcoholic cirrhosis (Case 1) and a 7-mm hypoechoic nodule in segment 5 of a 70-year-old man with chronic hepatitis C (Case 2). Contrast-enhanced US (CEUS), CE computed tomography, and CE magnetic resonance imaging of the nodules in both cases revealed hypervascularity in the early phase and washout in the late phase. CEUS with the use of perflubutane revealed washout in the portal phase, which differentiates these nodules from hepatocellular carcinoma. Histopathologically, the nodules showed proliferation of small 30-μm bile ducts with slight atypia. Immunohistochemically, these were positive for p16^INK4a and Ki67 index (0%-3%) and negative for EZH2, distinguishing them from cholangiolocellular carcinoma.