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Pancreas

Tumors

Intraductal oncocytic papillary neoplasm


Reviewer: Deepali Jain, M.D. (see Reviewers page)
Revised: 2 December 2012, last major update August 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.

General
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● First recognized in 1996 (Am J Surg Pathol 1996;20:980); also occurs in bile duct
● WHO classifies as oncocytic type of IPMN, with complex and arborizing papillae with delicate stroma; papillae are lined by 2-5 layers of cuboidal to columnar cells with abundant eosinophilic granular cytoplasm; nuclei are round, large, and fairly uniform and typically contain single, prominent, eccentrically located nucleoli (WHO)
● Mean age 62 years, no gender preference
● Low malignant potential
● Surgery may be curative
● Invasive in 20%, usually limited in extent with nested oncocytic pattern

IPMN v IOPN
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● IPMN more often invasive (50% v 20%)
● IPMN invades with a ductal or colloid pattern, not the oncocytic pattern of IOPN
● IPMN usually have intestinal papillae, not the pancreaticobiliary type of IOPN
● IOPN have intraepithelial lumina and are oncocytic
● IOPN does not have Kras mutation

Case reports
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● 76 year old man with painless jaundice (JOP 2010;11:49)
● 76 year old woman with 7.5 cm cystic mass (JOP 2007;8:206)

Gross description
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● Usually in head, mean 6 cm
● Mucin filled cysts with nodular papillary projections
● Often with dilated ducts communicating with main tumor

Gross images
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Partial gastrectomy, duodenum, pancreas, spleen, and partial omentum; pancreas shows solid area in head and multilocular lesion in tail with thick mucin and soft grey-brown luminal papillary masses (arrow); papillary mass also present in ductus choledochus (arrowhead), close to the surgical resection margin (*)


Cystic mass in body of pancreas contains coagulated blood with fibrin, mucus and nodular papillary projection

Micro description
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● Unilocular or multilocular papillary ducts composed of arborizing papillary structures with focal cribriform pattern, papillae lined by stratified and pseudostratified oncocytic cuboidal cells with intraepithelial lumina (highly specific, may contain mucin), abundant finely granular pink cytoplasm (due to mitochondria), prominent eccentric nuclei, microcystic spaces of 1-3 cell size (Stanford University)
● Architecturally complex with atypical cytology, mitotic figures, hyaline globules (negative for mucin) produce bud like appearance (Pathol Int 2010;60:48)
● Intraductal papillae may fuse and form large solid areas replacing the papillary architecture
● Invasive component, if present, may resemble intraductal component

Micro images
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Various images


Arborizing papillae and invasive areas characterized by small nests of cells with extracellular mucin accumulation; invasion front composed of cells with abundant eosinophilic cytoplasm surrounded by abundant mucin; perineural invasion exists as a peritumoral desmoplastic stromal reaction


Figure a-cyst wall lined by columnar pancreas duct epithelium with papillary projections
Figure b/c-tumor has variably complex, arborizing structures lined by plump cells with abundant eosinophilic cytoplasm
Figure d-cytoplasm is positive for anti-mitochondrial antibody



Oncocytic carcinoma: large cells with abundant, finely granular, eosinophilic cytoplasm, irregular nuclei, prominent nucleoli


MUC6+ (figure C)

Positive stains
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● MUC6 (Am J Surg Pathol 2010;34:364)
● Mucin in intraepithelial lumina, PTAH, 111-3 for mitochondria
● B72.3 (uniformly), CEA (focal)
● Focal apical MUC1+, dispersed MUC2+ (Am J Surg Pathol 2001;25:942)

Negative stains
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● p53, acinar cell markers (lipase, trypsin, chymotrypsin), neuroendocrine markers

Molecular description
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● No Kras, p53 or SMAD4 mutations (Am J Surg Pathol 2002;26:1071)

Electron microscopy description
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● Cells frequently packed with mitochondria

Electron microscopy images
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Oncocytic carcinoma in pancreatic tail: cells are packed with mitochondria and few glands

End of Pancreas > Tumors > Intraductal oncocytic papillary neoplasm


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