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Hepatobiliary and Pancreatic: Biliary intra‐epithelial neoplasia

A 79-year-old woman, with hypertension, diabetes mellitus, and chronic renal insufficiency, complained of abdominal distension and vomiting for a week. Abdominal ultrasound and subsequent magnetic resonance imaging showed a large multiloculated cystic lesion over left lobe liver (Fig. 1a). She had no hepatitis B or C virus infection. She had no jaundice, and the liver panels were all within normal range. Serum levels of CA19-9 and carcinoembryonic antigen were 234.1 U/mL (normal, < 37) and 2.1 ng/mL (normal, < 5.0). Percutaneous drainage revealed clear mucinous fluid without cytologic evidence of malignancy. She received left lateral segmentectomy, and the excised cyst contained elastic solid component with smooth inner lining (Fig. 1b, arrow). Histopathologically, the multilobulated “cyst” was actually the lumen of the dilated bile ducts, with chronic periluminal inflammation and fibrosis. The lining epithelial cells had abnormal changes from hyperplastic, to dysplastic, to multifocal micropapillary growth with nuclear atypia, but without invasion beyond the basement membrane (Fig. 1c). The pathological diagnosis was biliary intra-epithelial neoplasia (BilIN), with grade up to 3. BilIN is a premalignant biliary lesion of cholangiocarcinoma. The differential pathological diagnosis includes another premalignant biliary intraductal papillary neoplasm, which manifested microscopically as prominent papillary proliferation with distinct fibrovascular cores. Molecular difference of these two premalignant lesions between BilIN and biliary intraductal papillary neoplasm, however, in literature is inconsistent as yet. Clinically, BilIN is frequently observed in surgical margins of biliary tract cancer specimens and is considered to pose no prognostic implication. In our case, although postoperative course was smooth with reduction of serum CA19-9 and she enjoyed a 7-month symptom-free period, jaundice and biliary tract infection recurred and progressed thereafter. More aggressive surgical intervention in the first time might reverse the disease course.