1. PRKACA/PRKACB Fusions in Pancreatobiliary Intraductal Oncocytic Papillary Neoplasms Including Those With Atypical Morphology: An Analysis of 22 Cases Expanding Morphologic Spectrum.
- Author
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Mariko Tanaka, Kimiko Takeshita, Akiko Kunita, Kiyoshi Hasegawa, and Tetsuo Ushiku
- Subjects
BILE duct tumors ,ACADEMIC medical centers ,PAPILLARY carcinoma ,GENETIC markers ,TUMOR markers ,TUMOR grading ,PANCREATIC tumors ,CANCER cells ,HISTOLOGICAL techniques ,FLUORESCENCE in situ hybridization ,CARCINOGENESIS ,TUMOR classification ,MICROSCOPY - Abstract
Intraductal oncocytic papillary neoplasms (IOPNs) of the pancreatobiliary tract are considered a separate entity from intraductal papillary mucinous neoplasms (IPMNs), especially because of the distinct molecular alterations represented by PRKACA or PRKACB fusion. However, IOPNs display a spectrum of cytoarchitectural features. Typically, an IOPN is composed of arborizing papillae lined by layers of cells with oncocytic cytoplasm, prominent nucleoli, and intraepithelial lumina, while a significant subset shows atypical morphology: lack of the characteristic cytoarchitectural features such as arborizing papillae and prominent nucleoli, or mixture with nononcocytic IPMN-like components within a single lesion. To elucidate the tumorigenesis and morphologic spectrum of IOPNs, we analyzed 22 IOPNs, including those with atypical morphology for PRKACA/PRKACB fusions in each different component separately using fluorescence in situ hybridization. In total, 18 of 22 (82%) cases harbored PRKACA/PRKACB fusions, including 3 of 3 (100%) purely typical IOPNs and 15 of 19 (79%) IOPNs with atypical morphology. In the latter, PRKACA/PRKACB fusions were noted in atypical components as well as typical IOPN components. Notably, gastric-type IPMN-like components in the fusion-positive cases were usually low grade and had scattered neoplastic cells with eosinophilic cytoplasm, a morphologic feature suggestive of an early lesion of IOPN. In summary, most IOPNs with atypical morphology either lack characteristic cytoarchitectural features or exhibit a mixture with nononcocytic IPMN-like components, harbored PRKACA/PRKACB fusion as did typical IOPN components. Our observations expanded the morphologic spectrum of IOPNs. They are expected to be useful for correct diagnosis of this neoplasm. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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