LIVER/PANCREATOBILIARY

Question 1

Features of Intraductal Papillary Mucinous Neoplasm (IPMN)

Answer 1

• Arises from the main pancreatic duct and/or its branches.
• Most frequently located in head of pancreas.
• Flat or papillary tall columnar mucinous epithelium with small, basally located nuclei to complex architecture with high-grade nuclear features.
• The epithelium produces mucin and it accumulates in the ducts causing dilatation and a cystic appearance.
• The supporting stroma is dense and fibrotic.
• May consist of different cell types, including intestinal, pancreatobiliary, gastric, and oncocytic.
• May give rise to invasive carcinoma. Entire lesion should be submitted.
• Classified as low grade/borderline or high grade/CIS.
• DD:
• MCN (has ovarian-type stroma beneath epithelium & doesn’t communicate with ductal system).
• PanIN (IPMN>1cm grossly visible, MCN <0.5cm microscopic lesion)

Question 2

Criteria for Chronic Cholecystitis (3) and terminology(Page 1002 Odze)

Answer 2

1) Mononuclear inflammatory infiltrate in the lamina propria, +/- extension into the muscularis and pericholecystic tissues. Lymphocytes predominate over plasma cells and histiocytes, +/- few eosinophils and neutrophils may be also seen.
2) Fibrosis.
3) Metaplastic changes:
- Antral/pyloric (most common): Tubular glands in the LP composed of clear cells with mucin vacuoles.
The surface epithelium of the GB (tall columnar) usually undergoes focal or diffuse mucinous columnar metaplasia of gastric type.
- Intestinal: Glands with goblet cells, absorptive columnar cells, Paneth cells & endocrine cells.

Other findings:

• Rokitansky-Aschoff sinuses, hypertrophic muscularis (non-diagnostic in the absence of inflammation or metaplasia).
• Ulcerated mucosa.
• Ceroid granulomas: Collection of histiocytes with pale cytoplasm containing brown granules resulting from penetration of bile into submucosal tissues.
• Xanthogranulomas (foamy histiocytes predominate) and Foreign body-type granulomas.
• Dystrophic calcifications.

Terminology:

• Intraepithelial neutrophils in the setting of chronic cholecystitis: ‘chronic active cholecystitis’.
• Diffuse distribution of lymphoid follicles: ‘chronic follicular cholecystitis’.
• ‘Porcelain GB’: Due to diffuse dystrophic calcification of the wall.
• ‘Hyalinizing cholecystitis’: Dense hyaline fibrosis with sparse inflammation causing the gallbladder wall to become a thin, uniform shell.

Question 3

Features of Adenocarcinoma of gallbladder

Answer 3

• Elderly, F>M. Often incidental (at cholecystectomy).
• Imaging: diffuse thickening, polyp, occluding lumen.
• Risk Fx:
• Chronic inflammation (cholecystitis, cholelithiasis, chronic biliary infections).
• Porcelain GB
• PSC
• GI polyposis (FAP, Gardner, Peutz-Jeghers).
• Micro:
• Malignant glands, clusters, or individual cells invading the GB wall. Can be very well diff (look for infiltrative growth, alignment of the glands parallel to muscular wall, nuclear grooves, anisocytosis, mitosis).
• Usually associated with dysplasia/CIS.
• Multiple histologic variants: Papillary, intestinal type, gastric type, mucinous, clear cell, signet ring, adenosq, small/large cell NE, undiff & GB cystadenoca).
• IHC: (pancreaticobiliary type) CK7 & 19 +, CK20 +/-.
• DD: R-A sinuses, adenomyoma, acute cholecystitis (reactive atypia), ducts of Luschka, mets (rare).

Question 4

Features of (pancreatic) Solid-Pseudopapillary Tumour

Answer 4

• Young females, anywhere in the pancreas.
• Low grade malignant neoplasm of uncertain differentiation. Can metastasize to liver, peritoneum & lymph nodes (10-15%).
• Molecular: Mutations to the CTNNB1 gene leading to nuclear translocation of B-catenin (90-100% cases).
• Large, well demarcated solitary mass, solid to cystic.
• Micro:
• Monomorphic sheets of polygonal cells with uniform round/oval N, fine chromatin, nuclear grooves and moderate eosinophilic to clear/vacuolated cytoplasm.
• Admixed delicate vessels surrounded by hyalinised or myxoid stroma.
• Characteristic degenerative changes: Pseudopapillae formation, foamy Mo, cholesterol clefts, haemorrhage, calcification, pigment, areas of infarction.
• Infrequent mitosis.
• Special stain: PASD+ cytoplasmic globules.
• IHC: Nuclear B-catenin +, loss of membranous e-cadherin staining, PR + (nuclear), CD10+, SYN +/-, panCK +/-.
• DD: Pan NET, Acinar cell Ca.