When Morphology Falls Short: ATP1B1::PRKACB Fusion in a Morphologically Atypical Pancreatic Intraductal Oncocytic Neoplasm.
4 affiliations
- 1Department of Pathology, Jeonbuk National University Medical School, Jeonju, KOR.
- 2Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, USA.
- 3Department of Radiology, University of Minnesota, Minneapolis, USA.
- 4Department of Surgery, University of Minnesota, Minneapolis, USA.
Abstract
Intraductal oncocytic papillary neoplasm (IOPN) is a rare pancreatic intraductal neoplasm characterized by distinctive oncocytic morphology and recurrent gene fusions involving PRKACA or PRKACB. While conventional IOPN exhibits complex arborizing papillae lined by oncocytic epithelium, morphologically atypical lesions may lack these hallmark features and demonstrate overlap with intraductal papillary mucinous neoplasm (IPMN). A 76-year-old man presented with a pancreatic cystic lesion that remained radiographically stable over five years of surveillance and was initially considered indeterminate, though it was favored to represent a side-branch IPMN. Persistent main pancreatic duct dilation to 10 mm and a cyst measuring approximately 4.5 cm prompted multidisciplinary evaluation and subsequent pancreaticoduodenectomy. Histologic examination revealed a 3.4-cm intraductal neoplasm predominantly composed of foveolar-type and pancreatobiliary-type epithelium, with focal oncocytic differentiation and extensive high-grade dysplasia. The classic complex arborizing architecture characteristic of conventional IOPN was absent, and no invasive carcinoma was identified. RNA-based next-generation sequencing identified an ATP1B1::PRKACB fusion, while KRAS and GNAS alterations were not detected, strongly supporting its classification as a morphologically atypical intraductal oncocytic neoplasm within the IOPN spectrum. This case underscores the diagnostic value of integrating morphologic and molecular assessment when oncocytic differentiation is present, but conventional IOPN morphology is incompletely developed. Additionally, it provides uncommon longitudinal documentation of an IOPN-spectrum lesion that remained radiographically stable for five years.
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BibTeX
@article{han2026when,
title = {{When Morphology Falls Short: ATP1B1::PRKACB Fusion in a Morphologically Atypical Pancreatic Intraductal Oncocytic Neoplasm.}},
author = {Suyeon Han and Ying-Hsia Chu and Robben Schat and Ismail Elbaz Younes and David Brauer and David Cartwright and Amin Khalid and Kevin Turner and Byoung Uk Park},
journal = {Cureus},
year = {2026},
month = sep,
doi = {10.7759/cureus.117098},
url = {https://europepmc.org/article/MED/42953497},
note = {CC BY},
}
RIS
TY - JOUR
TI - When Morphology Falls Short: ATP1B1::PRKACB Fusion in a Morphologically Atypical Pancreatic Intraductal Oncocytic Neoplasm.
AU - Suyeon Han
AU - Ying-Hsia Chu
AU - Robben Schat
AU - Ismail Elbaz Younes
AU - David Brauer
AU - David Cartwright
AU - Amin Khalid
AU - Kevin Turner
AU - Byoung Uk Park
PY - 2026
DA - 2026/09/28
JO - Cureus
DO - 10.7759/cureus.117098
UR - https://europepmc.org/article/MED/42953497
AB - Intraductal oncocytic papillary neoplasm (IOPN) is a rare pancreatic intraductal neoplasm characterized by distinctive oncocytic morphology and recurrent gene fusions involving PRKACA or PRKACB. While conventional IOPN exhibits complex arborizing papillae lined by oncocytic epithelium, morphologically atypical lesions may lack these hallmark features and demonstrate overlap with intraductal papillary mucinous neoplasm (IPMN). A 76-year-old man presented with a pancreatic cystic lesion that remained radiographically stable over five years of surveillance and was initially considered indeterminate, though it was favored to represent a side-branch IPMN. Persistent main pancreatic duct dilation to 10 mm and a cyst measuring approximately 4.5 cm prompted multidisciplinary evaluation and subsequent pancreaticoduodenectomy. Histologic examination revealed a 3.4-cm intraductal neoplasm predominantly composed of foveolar-type and pancreatobiliary-type epithelium, with focal oncocytic differentiation and extensive high-grade dysplasia. The classic complex arborizing architecture characteristic of conventional IOPN was absent, and no invasive carcinoma was identified. RNA-based next-generation sequencing identified an ATP1B1::PRKACB fusion, while KRAS and GNAS alterations were not detected, strongly supporting its classification as a morphologically atypical intraductal oncocytic neoplasm within the IOPN spectrum. This case underscores the diagnostic value of integrating morphologic and molecular assessment when oncocytic differentiation is present, but conventional IOPN morphology is incompletely developed. Additionally, it provides uncommon longitudinal documentation of an IOPN-spectrum lesion that remained radiographically stable for five years.
SN - 2168-8184
ER -