2018 Current Issues in Surgical Pathology Summary (not actual lecture) Intrahepatic cholangiocarcinoma Histologic spectrum, novel markers and molecular assays Sanjay Kakar, MD University of California, San Francisco Intrahepatic cholangiocarcinoma Molecular alterations and histologic classification Diagnostic challenges Metabolic genes Genetic changes: ICC IDH1 IDH2 Chromatin remodeling genes BAP1 ARID1A PBRM1 Other mutations Fusion events KRAS BRAF FGFR2 ROS1 19-36% 0-6% 7-29% 19-36% 11-17% 24% 3% 6-50% 9% Schulze, Nat Genetics, 2015 Zhou, Nat Commun, 2014 Moeini, Clin Cancer Res 2016 1
ICC vs. HCC Genetic change β-catenin mutation TERT promoter mutation IDH mutations PBRM1 mutation FGFR2 fusion Hepatocellular carcinoma 20-30% 30-50% Rare Absent Absent Intrahepatic cholangiocarcinoma Uncommon Rare 19-36% 6-50% ICC vs. metastatic adenocarcinoma Genetic change IDH mutations BAP1 mutation PBRM1 mutation SMAD4 mutation FGFR2 fusion ICC Biliary AC GB PDAC Eso/Gastric 19-36% 0-7% 0 0 0 7-29% 0-10% 0 <1% 3% 11-17% 5% 20% 4-6% 0 0-4% 10-25% 0 35-60% 8% 6-50% 0-5% 20% 0 2-9% Intrahepatic cholangiocarcinoma Histologic classification Adenocarcinoma Histologic subtypes Well-differentiated Moderately-differentiated Poorly-differentiated Mucinous Signet ring Clear cell Lymphoepithelioma-like Sarcomatoid Adenosquamous Squamous 2
Intrahepatic cholangiocarcinoma Proposed classification #1 Classification based on size of glands Large duct type (Mucin-ICC) Small duct-type (Mixed-ICC) Cholangiolocellular Located close to hilum Glands typically large Mucin-positive Located at periphery Glands typically small Mucin-negative Ductular reaction-like pattern Komuta, Hepatol 2012 Intrahepatic cholangiocarcinoma Proposed classification #2 Conventional ICC Unconventional ICC Classification #2 With biliary features 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 3
Intrahepatic cholangiocarcinoma Diagnostic 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 4
Glands Biliary hamartoma Dilated ducts with curvilinear outlines Bile duct adenoma 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 Growth pattern Stroma Cytologic atypia Bile duct adenoma -Well-demarcated at interface -Grow around portal tracts Typically collagenized in center, can be cellular Mild Architecture Tubular glands, can be angulated Adenocarcinoma -Destructive growth -Portal invasion Desmoplastic Mild to marked 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 5
Bile duct adenoma Variant features Clear cell change Oncocytic change Alpha-1-antitrypsin globules Granulomas Bile duct adenoma Benign neoplasm or reactive process Reactive proliferation related to prior injury Peribiliary gland hamartoma Benign neoplasm Bile duct adenoma Study Pujals, Hepatology 2015 Pujals, Histopathol 2015 Angkathunyakul, Histopathol 2017 Result 53% had BRAF V600E mutation 53% positive for VE1 antibody by immunohistochemistry 87.5% had BRAF V600E mutation 6
BRAF mutation in ICC Study Result Goeppert, Mod Pathol 2014 Zhu, Ann Surg Oncol 2014 ICC: 5/159 (3%) Extrahepatic biliary, GB: negative ICC: 4.9% Lee, JCP 2016 Extrahepatic biliary: 1% BDA vs adenocarcinoma Immunohistochemistry: p53, Ki-67 IHC p53 Strong diffuse staining Ki-67 index >10% Result 35% ICC 60% metastatic PDAC None: bile duct adenoma (patchy weak to moderate staining) ICC: 88.5% (mean >20%) BDA: none (mean 2%) Tan, AIMM 2004 Hornick, AJSP 2005 Tsokos/Gill, Histopathol 2016 IHC BDA vs adenocarcinoma Immunohistochemistry: Other assays 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 7
Cholangiolocellular carcinoma Histologic criteria for diagnosis Study Microscopic Description Inconsistencies Kozaka, 2007 small tubular or acinar or cord-like structures, resembling reactive bile ductules 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 Some studies: Small tubular glands enough for diagnosis, did not require branching configuration Some studies: CCC divided into well, moderate and poorly differentiated categories 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 8
Cholangiolocellular carcinoma Well-differentiated ICC CD56 in CCC positive 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 9
Adenocarcinoma Any differentiation ICC vs metastatic adenocarcinoma Pancreas, biliary tree Upper GI ICC vs PDAC Immunohistochemistry: not widely studied Diagnosis ICC PDAC S100PpVHL+ MUC5AC- CK17- S100P+ pvhl- MUC5AC+ CK17+ IHC results Lok, Hum Pathol 2014 ICC vs PDAC Other assays Diagnosis ICC PDAC BAP1 loss Albumin ISH positive BAP1 intact Albumin ISH negative IHC results 10
BAP1: loss in tumor cells BAP1 loss Poorly differentiated ICC vs HCC ICC with solid/trabecular growth pattern Scirrhous HCC Combined HCC-cholangiocarcinoma 11
Cholangiocarcinoma HCC-like area HCC-like area CK19+ (Arg neg) Scirrhous HCC 12
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 13
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% Arginase-1 95% 95% Glypican-3 95% 70-80% Matsuura, Histopath, 2005 Krings/Kakar, Mod Pathol 2013 HCC Combined HCC-CC 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 14
Arginase-1 CK19 Arginase-1 CK19 Intrahepatic cholangiocarcinoma AJCC 8 th edition T category T1 T2 T3 T4 Definition T1a: Solitary tumor <5 cm without vascular invasion T1b: Solitary tumor >5 cm without vascular invasion Solitary tumor with intrahepatic vascular invasion, or multiple tumors, with or without vascular invasion Tumor perforates visceral peritoneum Tumor involving local extrahepatic structures by direct invasion 15
Intrahepatic cholangiocarcinoma AJCC 7 th edition T category T1 T2 T3 T4 Definition Solitary tumor without vascular invasion T2a: Solitary with vascular invasion T2b: Multiple tumors Involving visceral peritoneum or direct invasion into extrahepatic structures 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 16
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 17
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 18