J esús Javier Sola
Hospital San Pedro, Logroño

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[565] Unusual Immunohistochemistry Staining Patterns Encountered in
Cancers Screened for Lynch Syndrome.
Adams R, Geiersbach K, Tripp SR, Samowitz WS. University of Utah Health Sciences Center, ARUP Institute for Clinical &
Experimental Pathology, Salt Lake City, UT; ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT
• 3564 casos de neoplasias asociadas a SL (colon, endometrio, otros)
• 20% de alteraciones en el patrón de IHQ de MMRP (757)
• 13% de patrones “anormales o inusuales” (93)
• Heterogeneidad intratumoral (Colon 22/57)
• Alteraciones en más de un gen (Colon 12/57)
• Tto previo, artefacto, desconocido (Colon 24/57)
¿Son tan frecuentes los patrones inusuales? ¿Cómo reflejar estos hallazgos en nuestros informes?

[746] Retained Colorectal Carcinoma MLH1 Expression in Lynch
Syndrome Patients Carrying a Germline MLH1 Mutation.
Rosty C, Clendenning M, Win AK, et al. Envoi Pathology, Brisbane, Australia; University of Melbourne, Melbourne, Australia;
Sullivan Nicolaides Pathology, Brisbane, Australia; Colon Cancer Family Registry Investigators, Multiple Cities, Multiple States
• Registro de Cáncer Colon Familiar: tumores con pérdida exclusiva de
PMS2, 72 casos
• Mutación en línea germinal de PMS2 en 78% (59)
• 12/17 casos secuenciación MLH1
• 7/12 mutación línea germinal MLH1
• Mutaciones missense con retención de la antigenicidad de la proteína
Pérdida aislada de PMS2 sin mutación en línea germinal, testar MLH1

[747] Discordant Mismatch Repair Protein Immunoreactivity in Lynch
Syndrome-Associated Neoplasms: A Recommendation for Screening
Synchronous/Metachronous Lesions.
Roth RM, Hampel H, Arnold CA, Frankel WL. Ohio State University Wexner Medical Center, Columbus, OH
• 13 pacientes con 29 sinc/meta NASL
• 31% (4) con patrones discordantes, 3 con tumores sin pérdida
MMRP
• Relevante testar todos los tumores si sospecha clínica
[767] Comparison of Mismatch Repair Protein Immunohistochemistry in
Matched Colorectal Adenocarcinoma Biopsy and Resection Specimens
Steinbauer B, Findeis-Hosey B. University of Rochester Medical Center, Rochester, NY
• 43 pacientes con biopsia/pieza. 23 alteración MMRP
• 100% concordancia con MMRP intactas
• 87% concordancia total. 100% pérdida al menos de 1 proteína

[624] Annexin A10 Is Useful in Screening for Lynch Syndrome By
Decreasing the Need for MLH1 Promoter Hypermethylation: A
Consecutive Analysis of 575 Colorectal Adenocarcinomas.
Esnakula A, Carver P, Pai RK. Cleveland Clinic, Cleveland, OH
• 575 casos consecutivos ADC. 60 pérdida MLH-1. 53 IHQ AnA10
• 70% de mutación en BRAF, 33% AnA10 positivos
• 13/16 hipermetilación promotor MLH1, 46 % AnA10 positivos
• 3/16 sin hipermetilación promotor MLH1, 0% AnA10 positivos
Los autores sugieren que la IHQ para Anexina A10 puede sustituir al estudio de hipermetilación del promotor MLH1 en un 40% casos

[631] Prospective BRAF V600E Mutation Testing of dMMR Colorectal
Cancer: Detailed Correlation With Patholological and Clinical Features
Geraghty R, Boyle L, McCarthy A, Mohan H, et al. St. Vincent's University Hospital and Centre for Colorectal Disease, Dublin,
Ireland
• 226/2165 dMMRP (12%); 80 casos dMLH-1
• 60 % BRAF-mut
• 100% concordancia BRAF-mut entre IHQ específica y PCR
[644] BRAF Mutation Frequency Is Fewer in Asian Colorectal
Carcinomas (CRCs) Patients and Immunohistochemical Detection of
BRAF V600E Mutant Protein Using the VE1 Antibody in Colorectal
Carcinoma Is Highly Concordant With Molecular Testing
Hang JF, Liang WY, Li AFY, Chang SC. Veterans General Hospital-Taipei, Taipei, Taiwan; National Yang-Ming University School of Medicine, Taipei, Taiwan
• 430 ADC BRAF-mut por PCR e IHQ VE1
• 100% sensibilidad y 98% especificidad para IHQ VE1

[704] Clinicopathologic Comparison of Colorectal Carcinoma in Patients
With Suspected Lynch Syndrome without Germline Mutation (Lynch-Like
Syndrome) versus Patients with Germline Mutation (Lynch Syndrome)
Mas-Moya J, Dudley B, Brand RE, Pai RK. University of Pittsburgh Medical Center, Pittsburgh, PA, OH
• 3213 casos con 337 MSI-H; 114 sugestivos de SL, 48 estudio en línea germinal
• 33 (69%) SL: MSH2 (19), MLH1 (5), MSH6 (7), PMS2 (9)
• 15 sin alteraciones en línea germinal:
• MLH1/PMS2 (6), MSH2/MSH6 (7), PMS2 (3)
[704] Lynch Syndrome Screening: Discordance in MMR and Germline
Test Results
Mafnas CT, Martin BA, Ford JM, Longacre TA. Stanford University, Stanford, CA
• 21 casos con resultados discordantes, 14 de colon.
• Discusión y explicación confusa

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[571] Tracing Immunohistochemical and Molecular Markers of Serrated
Carcinoma Along the Serrated and Conventional Polyp Pathways of
Colorectal Carcinogenesis
Alcaraz-Mateos E, Garcia-Solano J, Garcia-Solano M, Carbonell P, Torres-Moreno D, Trujillo-Santos J, Perez-Guillermo M,
Conesa-Zamora P. Morales Meseguer University Hospital, Murcia, Spain; Santa Lucia University Hospital, Cartagena, Murcia,
Spain; Virgen Arrixaca University Hospital, Murcia, Spain
[584] A Clinicopathological and Molecular Analysis of 107 Sessile
Serrated Adenomas With Dysplasia
Bettington M, Walker NI, Rosty C, Brown I, Clouston AD, Pearson SA, McKeone DM, Leggett BA, Whitehall VLJ. QIMR
Berghofer Medical Research Institute, Brisbane, Australia; University of Queensland, Brisbane, Australia; Envoi Pathology,
Brisbane, Australia; Queensland Health, Brisbane, Australia; Royal Brisbane and Women's Hospital, Brisbane, Australia
[722] Immunohistochemical and Molecular Findings in Sessile Serrated
Polyps With Dysplasia
Panarelli N, Samowitz WS, Pai RK, Vaughn CP, Qin L, Yantiss RK. Weill Cornell Medical College, New York, NY; University of
Utah, Salt Lake City, UT; Cleveland Clinic, Cleveland, OH
[734] Phenotype-Genotype Correlation in Serrated Precursor Lesions of the Colon based on Recent Classifications
Rau T, Aust D, Baretton G, Eck M, Erlenbach-Wunsch K, Hartmann A, Lugli A, Stohr R, Vieth M, Zlobec I, Katzenberger T.
Institute of Pathology, University Bern, Bern, Switzerland; Institute of Pathology, University Hospital, Dresden, Germany;
Institute of Pathology, Hospital Aschaffenburg, Aschaffenburg, Germany; Institute of Pathology, Friedrich-Alexander-University
ErlangenNürnberg, Erlangen, Germany

• El adenoma serrado sésil (SSA) es el precursor más probable del adenocarcinoma serrado, con el que comparte perfil inmunohistoquímico y molecular, seguido del adenoma velloso convencional
• El 72% de los SSA con displasia son dMMRP, con 95% de mutaciones en BRAF y expresión aberrante de CK7 y CK20
• Hay diferencias en las alteraciones moleculares e inmunohistoquímicas entre las zonas de displasia, dependiendo de de su morfología (serrado, convencional o mixto), y el resto del pólipo sin displasia (BRAFmut, Anexina A10), coexistiendo ambas vías en la misma lesión
• El adenoma serrado tradicional (TSA) puede mostrar tanto alteraciones propias de la vía serrada (BRAFmut) como de la vía convencional (KRASmut), lo que sugiere la posibilidad de establecer subgrupos de este tipo de lesiones

[574] DNA Methylation Array Shows Overlapping Methylation Profiles in
Hyperplastic Polyps (HP) and Sessile Serrated Adenoma/Polyps
(SSA/P) of the Colorectum
Andrew AS, Li J, Koestler D, Tsongalis GJ, Marsit CJ, Butterly L, Amos CI, Srivastava A. Dartmouth-Hitchcock Medical Center,
Lebanon, NH; Brigham & Women's Hospital, Boston, MA
[610] Detection of the Loss of Hes1 Expression Differentiate Sessile
Serrated Adenoma/polyp From Hyperplastic Polyp
Cui M, Awadallah A, Liu W, Xin W. University Hospital Case Medical Center, Cleveland, OH; Case Western Reserve University,
Cleveland, OH
[634] Co-Expression of MUC5AC and TFF1 Distinguishes Sessile
Serrated Adenomas/Polyps From Hyperplastic Polyps
Hannah E Goyne, Magomed Khaidakov, Curt H Hagedorn, Laura W Lamps, Keith Lai. University of Arkansas for Medical
Sciences, Little Rock, AR

• 35 pólipos hiperplásicos (PH) y 42 adenomas serrados sesiles (SSA) no difieren significativamente en cuanto a la hipermetilación de
>485000 islas CpG a lo largo de todo el genoma, lo que sugiere mecanismos epigenéticos de desarrollo similares
• La pérdida de la expresión de Hes1 tiene una sensibilidad del 91% y una especificidad del 100% para el diagnóstico diferencial entre PH y
SSA. Hes1 interviene en la diferenciación de las células intestinales por la vía Notch
• En 5 PH y 12 SSA la coexpresión intensa de MUC5AC y TFF1, permite diferenciar SSA de PH. Ámbos se expresan en mucosa gástrica y no en mucosa de colon normal, y esta expresión se correlaciona con estudios de expresión previa de RNA

[625] BRAF Mutations in Sessile Serrated Polyps Associated With
Inflammatory Bowel Disease and Comparison With Sporadic
Counterparts
Esnakula A, Pai RK, Shadrach B, Liu X, Allende A. Cleveland Clinic, Cleveland, OH
[670] Serrated Colorectal Polyps in Inflammatory Bowel Disease
Ko HM, McBride RB, Cui M, Ye F, Zhang D, Ullman TA, Harpaz N, Polydorides AD. Mount Sinai Hospital, NY; Icahn School of
Medicine at Mount Sinai, New York, NY
[772] Clinical, Histologic, and Immunophenotypic Features of Serrated
Polyps in Patients With Inflammatory Bowel Disease
Tarabishy Y, Nalbantoglu I. Washington University, St. Louis, MO

• Entre 20 SSP esporádicos y 30 SSP en el contexto de EII no hay diferencias significativas en ningún dato clinicopatológico, ni en el porcentaje de casos con BRAFmut (70% vs 86%)
• En 78 SPs de 6602 pacientes con EII, la progresión a displasia o carcinoma es muy inferior en los casos de SSA de tipo esporádico sin displasia con respecto a TSA con displasia de tipo convencional
• Los pólipos serrados en pacientes con EII tiene una distribución topográfica, morfología y perfil inmunohistoquímico (ki67, BRAF y beta-catenina) completamente superponibles a los de los pacientes sin EII

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[591] Gastrointestinal Tract Adenocarcinomas Display Intratumoral
Heterogeneity Detectable By 47 Gene Next Generation Sequencing
Panel
Braxton DR, Morrissette JJD, Furth EE. University of Pennsylvania, Philadelphia, PA
DNA was extracted from FFPE samples(Qiagen), enriched for 47 genes
(TruSeq cancer panel), and sequenced on a MiSeq (Illumina, CA). Variant calls were made by an in-house bioinformatic pipeline. AI and SC were called based on allele frequencies and percent tumor.
Results: A total of 75 cases were studied with 166 variants detected for a mean of 2.2 (stdev 1.2) per case and an average read depth of 6759. AI was detected in 49/166(30%) variants in 36/75(48%) cases. TP53, KRAS, and APC were the most frequently mutated genes showing AI. SC was detected in 11/75(15%) cases with PIK3CA(3/11), FBXW7(2/11), and
TP53(2/11) being the most frequent genes defining SC. Evolving subclones which harbored actionable mutations were only found in resection/excisions and cases with greater than 25% tumor.

[710] Genotype Driven Anti-Cancer Therapies for Colon Cancer
Mockus BS, Stafford G, Potter C, Ananda G, Hinerfeld D, Tsongalis GJ. The Jackson Laboratory for Genomic Medicine,
Farmington, CT; The Jackson Laboratory for Mammalian Genomics, Bar Harbor, ME; Geisel School of Medicine at Dartmouth and Dartmouth-Hitchcock Medical Center, Lebanon, NH
DNA from ten colon adenocarcinoma FFPE samples was sequenced on
Illumina HiSeq 2500 or MiSeq sequencers using a CLIA-certified 358-gene targeted sequencing assay. Actionable variants were defined as: 1) gene variant associated with an approved drug in colon cancer, 2) gene variant associated with an approved drug in another tumor type, 3) gene variant associated with a drug that is in an active colon or solid tumor clinical trial, and/or 4) gene variant confers resistance to a drug.
An average of 2.7 actionable variants were identified per sample with KRAS mutations in exons 12 and 13 being the most common. The average number of therapeutic options was 1.5, 10.7, and 15.4 for FDA approved drugs in colon cancer, FDA approved drugs in other tumor types, and investigational drugs in clinical trials, respectively.

[728] Next Generation Sequencing (NGS) Identifies Mutational
Distinction Between Synchronous and Metachronous Distant
Metastases of Colorectal Carcinoma (CRC)
Patel S, Farahani N, Chevarie-Davis M, Andy P, Aguiluz A, Riley C, Hodge J, Alkan S, Lopategui JR. Cedars-Sinai Medical
Center, Los Angeles, CA
Thirty-two samples from eleven patients with metastatic CRC were selected from institutional archives. Seven patients had synchronous distant metastases and 4 patients developed metachronous distant metastases.
Samples were evaluated using the AmpliSeq cancer panel v2 with aberrations filtered to include only non-synonymous amino acid changes in
2855 "hotspots" frequently mutated in 50 cancer genes.
Across all patients, 25 different hotspot mutations were identified involving
TP53, APC, BRAF, PTEN, PIK3CA, KRAS, SMAD4, FBXW7, and KDR.
Mutations per case ranged from 1-4. About half of synchronous DM demonstrated completely divergent mutations from the PT. This is in contrast to metachronous DM in which all had the same or overlapping mutations as the PT.

[583] Molecular Characterization of Acquired Resistance To Anti-EGFR
Monoclonal Antibodies in Colorectal Cancer Patients
Bellosillo B, Dalmases A, Martinez A, Iglesias M, Gonzalez I, Salido M, Busto M, Sanchez J, Vidal J, Clave S, Moragon E,
Pairet S, Bellmunt J, Serrano S, Rovira A, Albanell J, Montagut C. Hospital del Mar, Barcelona, Spain
To increase our understanding on mechanisms of acquired resistance to anti-EGFR treatment, we evaluated molecular changes before and after receiving anti-EGFR treatment in paired tumor samples from CRC patients.
37 colorectal cancer patients were included in the study. Mutations in
EGFR, KRAS, NRAS, BRAF and PIK3CA genes were evaluated by nextgeneration pyrosequencing. KRAS, EGFR and HER2 gene amplification was evaluated by FISH. Molecular analysis of samples at the time of progression showed the emergence of novel alterations in 81% of patients.
RAS (40% of patients) mostly affected exons 3 and 4, PIK3CA (19%), BRAF
(11%), EGFRS492R (8%) and novel mutations in EGFR ectodomain (5%).
FISH showed EGFR and HER2 gene amplification in 57% and 18%. In 9 patients the mutations were already detected by next-generation sequencing at diagnosis as well as in 8 patients EGFR and HER2 amplification.

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[743] Programmed Cell Death Ligand 1 Expression Is Associated With
BRAF Mutation, Microsatellite Instability, Medullary Morphology, and
Helps To Characterize Tumor Behavior in Colorectal Carcinoma
Rosenbaum M, Bledsoe J, Huynh TG, Mino-Kenudson M. Massachusetts General Hospital, Boston, MA
We performed immunohistochemistry for PD-L1 (clone: E1L3N #13684,
1:200, Cell Signaling Technology, MA) on tissue microarrays (TMAs) consisting of 336 tissue cores from 164 CRC cases. Mutational and microsatellite instability (MSI) status was known in most cases. The same
TMAs were stained with anti-CD8 (clone: IgG2b 4B11, RTU, Leica, IL).
Fifteen cases (9%) showed positive membranous staining for PD-L1 (PD-
L1-P). PD-L1 expression correlated with abundant TILs (P<0.01), the presence of BRAF V600E mutation (P<0.01), and MSI-H. The PD-L1-P cases all demonstrated a medullary phenotype.

[776] Expression of PDL1 in Gastric Adenocarcinomas and Associated
Tumor Infiltrating Lymphocytes
Thompson E, Abdelfatah E, Taube J, Duncan MD, Ahuja N, Kelly R, Anders R. Johns Hopkins, Baltimore, MD
34 cases of invasive gastric adenocarcinoma were stained for PDL1 and the tumors and associated TILs were scored for PDL1 expression. Tumors with greater than 5% membranous staining were considered PDL1 positive. TILs were scored as no significant staining (0), less than 50% (focal) or greater than 50% (high). 4/34 tumors (12%) showed membranous PDL1 expression. Overall, 45% of gastric adenocarcinomas showed some level of
PDL1 expression among TILs with 27% showing focal interface expression and 18% showing high expression. 55% of TILs in had no expression of
PDL1. High PDL1 expression on TILs correlated with lower tumor stage at presentation, while deaths occurred in a higher percentage of patients with
PDL1 positive tumors than negative tumors.

[642] Tumor-Infiltrating Lymphocytes in Colorectal Adenocarcinomas:
Tracking the Immune Response Through Different Tumor Stages
Hallas C, Stamm M, Falk M, Tiemann M. Hematopathology Hamburg, Hamburg, Germany; Semmelweis University Medical
Faculty, Asclepios Campus Hamburg, Hamburg, Germany
B-cells (CD19+ and CD20+, resp.), T-cells (CD3+, CD4+, and CD8+), activated T-cells (CD25+), Treg (FoxP3+) and tissue macrophages
(histiocytes, CD68+) were stained by immunohistochemistry and counted in
131 colorectal adenocarcinomas of different stages. The immune response in colorectal tumors was dominated by T cells in all tumor stages. CD4+ cells were more abundant than CD8+ cells throughout all TNM stages except for pT2. In pT2, CD8+ T cells were significantly more abundant.The
high CD8+ count in pT2 correlated with increased numbers of activated
CD25+ T cells and histiocytes.
The strongest CD8+ cytotoxic T cell response was found in pT2, pointing towards a functional immune response in early stage disease.

[755] Characterization and Clinical Value of Tumor Infiltrating
Lymphocytes (TILs) in Gastric Cancer
Schalper K, Carvajal-Hausdorf D, Syrigos KN, Rimm DL. Yale University, New Haven, CT; University of Athens, Sotiria General
Hospital, Athens, Greece
Using multiplexed quantitative fluorescence (QIF), we simultaneously measured the levels of CD3 (T cells), CD8 (cytotoxic T cells), CD20 (Blymphocytes), cytokeratin (tumor cells) and DAPI (all nuclei) in a retrospective collection of 302 GCs represented in tissue microarray format.
The level of TILs was scored using the AQUA method. Measurements were performed in two cores obtained from different tumor areas to assess heterogeneity of the markers.
GCs with diffuse histology showed higher levels of CD20 than intestinal neoplasms (P=0.04). All markers showed a trend for lower levels in stage IV tumors. Using the median score as cutpoint, elevated CD8 but not CD3 or
CD20 signal was significantly associated with longer overall survival (logrank P=0.004).