LAUSR

pink-tan tissue pieces. The mucosa was tan-pink and congested with a 2.0 × 2.0 × 0.2-cm area of irregular thickening. The wall thickness measured up to 0.3 cm. Microscopic examination revealed exuberant tubulopapillary growth with lowto high-grade dysplasia; focal flat dysplasia; oncocytic, pyloric, and goblet cell metaplasia; marked acute and chronic inflammation; and abscess formation. No invasion of the gallbladder wall or Rokitansky-Aschoff sinuses were identified. The tumor cells were immunoreactive for CK20 (strong) and patchy positive for CK7, MUC1, and MUC5 AC. Tumor cells were negative for MUC2, MUC6, CDX2, and Hep-par. Based on these findings, a diagnosis of intracholecystic papillary-tubular neoplasm, pancreaticobiliary type, with high-grade dysplasia and clear margins was made (T1 lesion). Conclusion: ICPNs larger than 1 cm, as in this case, are more commonly of the biliary type showing cuboidal cells, prominent nucleoli, and MUC1 positivity and often associated with high-grade dysplasia and invasive cancers. ICPN patients have a propensity to develop biliary tract carcinomas, especially when associated with extensive high-grade dysplasia. These tumors must be sampled adequately, with documentation of tumor characteristics and presence or absence of invasive component.