Archives of Pathology and Laboratory Medicine, cilt.147, sa.12, ss.1390-1401, 2023 (SCI-Expanded)
Context.—Tumoral (grossly visible) intraductal neoplasms of the bile ducts are still being characterized. Objective.—To investigate their morphologic, immunohistochemical, and molecular features. Design.—Forty-one cases were classified as gastric-, intestinal-, pancreatobiliary-type intraductal papillary neoplasm (IPN), intraductal oncocytic papillary neoplasm (IOPN), or intraductal tubulopapillary neoplasm (ITPN) on the basis of histology. All neoplasms were subjected to targeted next-generation sequencing. Results.—The mean age at diagnosis was 69 years (42–81 years); male to female ratio was 1.3. Most neoplasms (n ¼ 23, 56%) were extrahepatic/large (mean size, 4.6 cm). The majority (n ¼ 32, 78%) contained high-grade dysplasia, and 68% (n ¼ 28) revealed invasion. All gastric-type IPNs (n ¼ 9) and most ITPNs/IOPNs showed consistent colabeling for CK7/MUC6, which was less common among others (P ¼ .004). Intestinal-type IPNs (n ¼ 5) showed higher rates of CK20 expression than others (P, .001). Overall, the most commonly mutated genes included TP53 and APC, while copy number variants affected ELF3 and CDKN2A/B. All gastric-type IPNs contained an alteration affecting the Wnt signaling pathway; 7 of 9 (78%) showed aberrations in the MAPK pathway. Mutations in APC and KRAS were common in gastric-type IPNs as compared with others (P ¼ .01 for both). SMAD4 was more frequently mutated in intestinal-type IPNs (P ¼ .02). Pancreatobiliary-type IPNs (n ¼ 14) exhibited frequent alterations in tumor suppressor genes including TP53, CDKN2A/B, and ARID2 (P ¼ .04, P ¼ .01 and P ¼ .002, respectively). Of 6 IOPNs analyzed, 3 (50%) revealed ATP1B1-PRKACB fusion. ITPNs (n ¼ 6) showed relatively few recurrent genetic aberrations. Follow-up information was available for 38 patients (median, 58.5 months). The ratio of disease-related deaths was higher for the cases with invasion (56% versus 10%). Conclusions.—Tumoral intraductal neoplasms of the bile ducts, similar to their counterparts in the pancreas, are morphologically and genetically heterogeneous. (Arch Pathol Lab Med. 2023;147:1390–1401; doi: 10.5858/arpa.2022-0343-OA).