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Intrahepatic cholangiocarcinomaHistologic spectrum, novel markers and

molecular assays

Sanjay Kakar, MD University of California, San Francisco

2018 Current Issues in Surgical Pathology

Summary (not actual lecture)

Intrahepatic cholangiocarcinoma

• Molecular alterations and

histologic classification

• Diagnostic challenges

Schulze, Nat Genetics, 2015

Zhou, Nat Commun, 2014

Moeini, Clin Cancer Res 2016

Genetic changes: ICCMetabolic genes

IDH1IDH2

19-36%0-6%

Chromatin remodeling genesBAP1

ARID1APBRM1

7-29%19-36%11-17%

Other mutationsKRASBRAF

24%3%

Fusion eventsFGFR2ROS1

6-50%9%

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ICC vs. HCC

Genetic change Hepatocellular carcinoma

Intrahepaticcholangiocarcinoma

β-catenin mutationTERT promoter mutation

20-30%30-50%

UncommonRare

IDH mutations PBRM1 mutationFGFR2 fusion

RareAbsentAbsent

19-36%

6-50%

ICC vs. metastatic adenocarcinoma

Genetic change

ICC BiliaryAC

GB PDAC Eso/Gastric

IDHmutations

19-36% 0-7% 0 0 0

BAP1 mutation

7-29% 0-10% 0 <1% 3%

PBRM1mutation

11-17% 5% 20% 4-6% 0

SMAD4mutation

0-4% 10-25% 0 35-60% 8%

FGFR2 fusion

6-50% 0-5% 20% 0 2-9%

Intrahepatic cholangiocarcinoma

Histologic classification

Adenocarcinoma Well-differentiated

Moderately-differentiated

Poorly-differentiated

Histologic subtypes Mucinous

Signet ring

Clear cell

Lymphoepithelioma-like

Sarcomatoid

Adenosquamous

Squamous

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Intrahepatic cholangiocarcinomaProposed classification #1

Classification based on size of glands

Large duct type

(Mucin-ICC)

Located close to hilum

Glands typically large

Mucin-positive

Small duct-type

(Mixed-ICC)

Located at periphery

Glands typically small

Mucin-negative

Cholangiolocellular Ductular reaction-like pattern

Komuta, Hepatol 2012

Intrahepatic cholangiocarcinomaProposed classification #2

Classification #2

Conventional ICC With biliary features

Unconventional ICC Trabecular subtype

Hilar subtype

With predominant ductal plate

malformation

Cholangiolocellular

Intraductal neoplasia Intraductal papillary neoplasm

Intraductal tubulopapillary neoplasm

Sempoux, Sem Liv Dis 2011

Intrahepatic cholangiocarcinoma

• Molecular alterations and

histologic classification

• Diagnostic challenges

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Intrahepatic cholangiocarcinomaDiagnostic challenges

Well-differentiated

• BDA vs adenocarcinoma

Adenocarcinoma: any differentiation

• ICC vs metastatic adenocarcinoma

Poorly differentiated

• Hepatocellular carcinoma

Well-differentiated

Frozen section diagnosis

• Metastatic adenocarcinoma

• Benign biliary proliferation: Bile duct

adenoma or hamartoma

Benign biliary lesions

Biliary hamartoma (von Meyenburg complex)

• Dilated ducts with curvilinear outlines

• Inspissated bile

Bile duct adenoma

• Compact small to medium sized glands

• Round to oval contours, not dilated

• Scant stroma if small, larger lesions can have

prominent stroma

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Biliary

hamartoma

Bile duct

adenoma

Glands Dilated ducts with

curvilinear outlines

Compact small to medium

sized glands

Stroma Can be prominent Scant in small lesions, can

be prominent in large

lesions

Bile or

eosinophilic

material

Often present Absent

Bile duct adenoma Adenocarcinoma

Growth

pattern

-Well-demarcated at

interface

-Grow around portal

tracts

-Destructive growth

-Portal invasion

Stroma Typically collagenized in

center, can be cellular

Desmoplastic

Cytologic

atypia

Mild Mild to marked

Architecture Tubular glands, can be

angulated

Can be complex

Mitoses Absent Can be present

Bile duct adenoma

Challenging features

• Atypia enhanced by frozen artifact

• Angulated infiltrative glands

• Mucin can be present

• Stroma may simulate desmoplasia

• Variant histologic features

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Bile duct adenomaVariant features

• Clear cell change

• Oncocytic change

• Alpha-1-antitrypsin globules

• Granulomas

Bile duct adenomaBenign neoplasm or reactive process

• Reactive proliferation related to prior

injury

• Peribiliary gland hamartoma

• Benign neoplasm

Bile duct adenoma

Study Result

Pujals, Hepatology

2015

53% had BRAF V600E mutation

Pujals, Histopathol

2015

53% positive for VE1 antibody by

immunohistochemistry

Angkathunyakul,

Histopathol 2017

87.5% had BRAF V600E mutation

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BRAF mutation in ICC

Study Result

Goeppert, Mod

Pathol 2014

ICC: 5/159 (3%)

Extrahepatic biliary, GB: negative

Zhu, Ann Surg

Oncol 2014

ICC: 4.9%

Lee, JCP 2016 Extrahepatic biliary: 1%

BDA vs adenocarcinomaImmunohistochemistry: p53, Ki-67

IHC Result

p53

Strong diffuse

staining

35% ICC

60% metastatic PDAC

None: bile duct adenoma (patchy weak to

moderate staining)

Ki-67 index

>10%

ICC: 88.5% (mean >20%)

BDA: none (mean 2%)

Tan, AIMM 2004

Hornick, AJSP 2005

Tsokos/Gill, Histopathol 2016

BDA vs adenocarcinomaImmunohistochemistry: Other assays

IHC Result

DPC4 loss ICC: 5-10%; metastatic PDAC 50-60%

BDA: none

Mesothelin Metastatic PDAC: 64%

BDA: none

mCEA Metastatic PDAC: 92%

BDA: none

BAP1 loss ICC: 20-30%

BDA: none (limited experience)

Albumin ISH Metastatic PDAC: none

BDA: Positive

Hornick, AJSP 2005

Arora, Histopathol 2016

Misumi, Histopathol 2017

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Cholangiolocellular carcinoma Histologic criteria for diagnosis

Study Microscopic Description Inconsistencies

Kozaka, 2007 • small tubular or acinar or cord-like structures, resembling reactive bile ductules

Some studies: • Small tubular glands enough

for diagnosis, did not require branching configuration

Some studies:• CCC divided into well,

moderate and poorly differentiated categories

Komuta, 2008 • small monotonous glands• antler-like anastomosing

patterns • abundant hyalinized and/or

edematous fibrous stroma

Moeini, 2017 • glands strongly embedded in fibrous stroma

Rhee, 2018 • cuboidal to low columnar cells with scanty eosinophilic or amphophilic cytoplasm

• small monotonous glands

CCC: ‘stem cell’ features?

Study Stem Cell Markers

Kozaka, 2007 • NCAM (CD56): 75%

Komuta, 2008 • NCAM in 87%• CD133, c-kit, OCT4

Moeini, 2017 • SALL4: 75% • NCAM:100%

Rhee, 2018 • No difference in stem cell marker staining compared to intrahepatic cholangioCA

Cholangiolocellular carcinoma

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Cholangiolocellular carcinoma Well-differentiated ICC

CD56 in CCCpositive and negative case

EMA in CCC Luminal and cytoplasmic

EMA per literature

• Luminal

staining in CCC

• Cytoplasmic

staining in ICC

Komuta, Hepatol 2012

Kondo, Int Med 2015

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AdenocarcinomaAny differentiation

ICC vs metastatic adenocarcinoma

• Pancreas, biliary tree

• Upper GI

ICC vs PDACImmunohistochemistry: not widely studied

Diagnosis IHC results

ICC S100P-

pVHL+

MUC5AC-

CK17-

PDAC S100P+

pVHL-

MUC5AC+

CK17+

Lok, Hum Pathol 2014

ICC vs PDACOther assays

Diagnosis IHC results

ICC BAP1 loss

Albumin ISH positive

PDAC BAP1 intact

Albumin ISH negative

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BAP1: loss in tumor cells

BAP1 loss

Poorly differentiated ICC vs HCC

• ICC with solid/trabecular growth

pattern

• Scirrhous HCC

• Combined HCC-cholangiocarcinoma

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Cholangiocarcinoma HCC-like area

HCC-like area CK19+ (Arg neg)

Scirrhous HCC

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Hep Par, pCEA MOC31

Scirrhous HCC: Atypical features

• Atypical radiologic features

• Abundant stroma

• Immunophenotypic features

Negative: Hep Par 1, pCEA

Positive: MOC31, CK19

GPC-3 CK19

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Stain Scirrhous HCC Conventional HCC

Hep Par 1 17-20% 80-90%

pCEA 33% 60-80%

CK7 58-65% 0-20%

CK19 50% 0-10%

MOC31 64% 5-11%

Matsuura, Histopath, 2005Krings/Kakar, Mod Pathol 2013

Arginase-1 95% 95%

Glypican-3 95% 70-80%

Combined HCC-CC

HCC

• Morphology, arginase-1

• CK19: can be positive

CC

• Discrete glands, mucin +

• Negative arginase-1

• CK7, CK19 and/or MOC31

HCC-like area Well-formed glands

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Arginase-1 CK19

Arginase-1 CK19

Intrahepatic cholangiocarcinomaAJCC 8th edition

T category Definition

T1 T1a: Solitary tumor <5 cm without vascular invasionT1b: Solitary tumor >5 cm without vascular invasion

T2 Solitary tumor with intrahepatic vascular invasion, or multiple tumors, with or without vascular invasion

T3 Tumor perforates visceral peritoneum

T4 Tumor involving local extrahepatic structures by direct invasion

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Intrahepatic cholangiocarcinomaAJCC 7th edition

T category Definition

T1 Solitary tumor without vascular invasion

T2 T2a: Solitary with vascular invasionT2b: Multiple tumors

T3 Involving visceral peritoneum or direct invasion into extrahepatic structures

T4 Tumor with periductal invasion

Periductal invasion

• Intrahepatic CC, macroscopic types

Mass forming, periductal, intraductal, mixed

• Periductal: worse prognosis

Extensive intraductal growth: T4

• Problems

How extensive is 'extensive'

Recent studies do not confirm worse outcome

Hirohashi, Hepatogastroeterol 2002

Uno, Surg Today, 2012

Periductal growth pattern

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Intrahepatic cholangiocarcinoma, 3 cm, no VI

Summary

• Mutations in IDH1, PBRM1 and BAP1, and

FGFR2 fusion can help in distinction of ICC

from metastatic adenocarcinoma

• Mutation in IDH1 and PBRM1, and FGFR2

fusion along with absence of CTNNB1 and

TERT promoter mutation helps in distinction

from HCC

Summary

BAP1 loss by IHC

• Can help in distinction from PDAC and upper

GI metastatic adenocarcinoma

• Can help in distinction from benign biliary

lesions

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Summary

p53 and Ki-67 IHC

• Diffuse strong p53 staining supports

adenocarcinoma over bile duct adenoma

• Ki-67 proliferation index >10% is rare in bile

duct adenoma

Summary

HCC vs ICC

• Diagnosis has strong impact on treatment

• Sensitive markers like arginase-1 should be

used to identify HCC component

• ICC diagnosis should be based on stric t

criteria: discrete glands, mucin+, positive for

CK19/CK7, typically negative for

hepatocellular markers