8:00

INTRODUCTION.

8:05

PRIMARY MEDIASTINAL (THYMIC) LARGE B-CELL LYMPHOMA PRESENTING WITH GASTRIC PERFORATION Patricia Arboleda Ezcurra1, Ahmed Ayad 1, Caitlin Harmon 1, Vrinda Shenoy 1, Duffield Amy2. 1Mount Sinai West, NY, NY, USA. 2Mount Sinai Hospital, NY, NY, USA

8:17

EPSTEIN-BARR VIRUS-POSITIVE PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA Natasha Lewis, Ryan Barry, Ryan Robetorye. Mayo Clinic Arizona, Phoenix, AZ, USA

8:29

COMPOSITE CLASSIC HODGKIN LYMPHOMA-PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA: A CASE OF B-CELL PLASTICITY AND CLONAL RELATIONSHIP  JAGMOHAN SIDHU1, JOSEPH READLING2. 1UHS Hospitals, Binghamton, NY, USA. 2UHS Oncology, Binghamton, NY, USA

8:41

MEDIASTINAL AND CERVICAL LYMPHADENOPATHY IN AN 18-YEAR-OLD MALE Brent E. Harbaugh1, 2, Soumya Pandey1, 2. 1University of Arkansas for Medical Sciences, Little Rock, AR, USA. 2Arkansas Children's Hospital, Little Rock, AR, USA

8:53

18-YEAR-OLD FEMALE WITH MEDIASTINAL GRAY ZONE LYMPHOMA Chandler Sy, Ivo Sahbandar, Georgi Lukose, Jiani Chai, Shipra Kaicker, Nitya Gulati, Madhu Ouseph, Amy Chadburn. NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, USA

9:05

SUMMARY OF SUBMITTED CASES IN THIS CATEGORY.

PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA IN 23 Y/O FEMALE 4 YEARS AFTER DIAGNOSED WITH CLASSIC HODGKIN LYMPHOMA.   Andres Madrigal, Gerard Lozanski. The Ohio State University, Columbus, OH, USA

PRIMARY MEDIASTINAL LARGE B CELL LYMPHOMA WITH AN UNUSUAL MORPHOLOGY Folashade Adekunle, Ifeyinwa E Obiorah. University of Virginia Health system, Charlottesville, VA, USA

TEEN CHALLENGE: B-CELL LYMPHOMAS WITH MEDIASTINAL PRESENTATION Ahmed A Aljudi. Children's Healthcare of Atlanta, Atlanta, GA, USA

AN EBV-POSITIVE LYMPHOPROLIFERATIVE CASE AT THE INTERSECTION OF LYMPHOCYTE-RICH CLASSICAL HODGKIN LYMPHOMA AND NODULAR LYMPHOCYTE PREDOMINANT HODGKIN LYMPHOMA FNU Alnoor, Jennifer Chapman, Catalina Amador. University of Miami Miller School of Medicine, Miami, FL, USA

SMA-POSITIVE ANAPLASTIC LARGE CELL LYMPHOMA Rahmah M Arwani, Candace Reveles. University of Arizona, Tucson, AZ, USA

PEDIATRIC CASE OF PRIMARY MENINGEAL HODGKIN LYMPHOMA Alexander Besen, Alicia Schmidt, Mahlon Johnson, Jamie Flerlage, Chauncey Syposs. University of Rochester Medical Center, Rochester, NY, USA

PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA IN A TEENAGER FEMALE Natalie Ellington, Jun Mo, Dehua Wang. Rady Children's Hospital University of California, San Diego, CA, USA

PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA WITH NEGATIVE CD23 EXPRESSION Brittany Ewing, Melissa Stalling, Christopher Klonk. Akron Children's Hospital, Akron, OH, USA

CLASSIC HODGKIN LYMPHOMA WITH PAN T-CELL ANTIGEN EXPRESSION, MIMICKING ALK-NEGATIVE ANAPLASTIC LARGE CELL LYMPHOMA Giby V George1, W Richard Burack1, Siba El Hussein2. 1Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, USA. 2Department of Pathology, University of Vermont, Burlington, VT, USA

CLASSIC HODGKIN LYMPHOMA FOLLOWING PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA Emma Hawkins, Elizabeth Rinker. Medical University of South Carolina, Charleston, SC, USA

INCIDENTAL DETECTION OF MATERNAL CLASSIC HODGKIN LYMPHOMA THROUGH NONINVASIVE PRENATAL TESTING Muhammad Hussain1, Mark Ewalt2, Ahmet Dogan2, Shenon Sethi2. 1Temple University Hospital, Philadelphia, PA, USA. 2Memorial Sloan Kettering, New York, NY, USA

DIFFUSE LARGE B-CELL LYMPHOMA IN PEDIATRIC-ONSET INFLAMMATORY BOWEL DISEASE TREATED WITH ANTI-TNF INHIBITORS: ASSOCIATION WITH EZH2 MUTATIONS​ Irem S Isgor1, Qi Gao1, Efrat Luttwak2, Menglei Zhu1, Yanming Zhang1, Mark Ewalt1, Jyoti Kumar1, Benjamin Durham1, Megan Lim1, Gilles Salles2, ahmet Dogan1. 1Memorial Sloan Kettering Cancer Center, Department of Pathology and Laboratory Medicine, New York, NY, USA. 2Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA, New york, NY, USA

EBV-POSITIVE MEDIASTINAL B-CELL LYMPHOMA IN A YOUNG IMMUNOCOMPETENT ADULT: INITIAL 'GRAY ZONE' FEATURES WITH SUBSEQUENT CLASSICAL HODGKIN PHENOTYPE Kirill Karlin, Bartek Gryzwacz, Ruth Gichinga, Xiang Xu, German Pihan, Robert Willim. Beth Israel Deaconess Medical Center, Boston, MA, USA

MEDIASTINAL GREY ZONE LYMPHOMA Liping Li, Yi Sun. Rutgers University, New Brunswick, NJ, USA

A CHALLENGING CASE OF MEDIASTINAL CLASSICAL HODGKIN LYMPHOMA MIMICKING PRIMARY MEDIASTINAL B CELL LYMPHOMA.   Jane Lin1, Gholamali Jafari1, Mark Podberezin2. 1SUNY Downstate Health Sciences University, Brooklyn, NY, USA. 2Maimonides Medical Center, Brooklyn, NY, USA

EXPRESSION OF THE ACTIVATION MARKER CD38 ON CD4+ T-CELLS IN PEDIATRIC CLASSIC HODGKIN LYMPHOMA Meng Liu, Michael Wang. Department of Pathology and Laboratory Medicine Albany Medical Center, Albany, NY, USA

FAMILIAL CLASSIC HODGKIN LYMPHOMA: 9-YEAR-OLD BOY AND HIS MOTHER  Georgi Lukose, Chandler Sy, Ivo SahBandar, Madhu Ouseph, Rebecca Leeman-Neill, Amy Chadburn. Department of Pathology & Laboratory Medicine, Weill Cornell Medicine/NewYork-Presbyterian, New York, NY, USA

PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA WITH PROMINENT HISTIOCYTIC BACKGROUND IN A 12-YEAR-OLD BOY. Ngome L. Makia, Jeffrey W. Craig. University of Virginia Health System, Charlottesville, VA, USA

COMPOUND CLASSIC HODGKIN LYMPHOMA AND LARGE B-CELL LYMPHOMA IN MEDIASTINUM, KIDNEY, AND BONE, LIKELY RELATED TO MEDIASTINAL GREY ZONE LYMPHOMA Rachel A Mariani1, 2, Kristian T Schafernak1, 2. 1Phoenix Children's Hospital, Phoenix, AZ, USA. 2University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA

EBV POSITIVE MEDIASTINAL GRAY ZONE LYMPHOMA IN AN ADOLESCENT PATIENT Rodney R. Miles1, Madhu P. Menon1, Jeffrey R. Jacobsen1, Elaine S. Jaffe2. 1University of Utah Department of Pathology and ARUP Laboratories, Salt Lake City, UT, USA. 2Laboratory of Pathology, NCI, Bethesda, MD, USA

DIAGNOSTIC CHALLENGES IN SYNCHRONOUS CLASSIC HODGKIN’S LYMPHOMA AND PRIMARY MEDIASTINAL B-CELL LYMPHOMAS: COMPOSITE VS. GRAY ZONE LYMPHOMA Phuong Nguyen, Wen Fan, Abdelsalam Sharabi. Department of Pathology, Molecular and Cell Based Medicine Mount Sinai Health System, Mount Sinai West, New York, NY, USA

PRIMARY MEDIASTINAL LARGE B-CELL LYMPHOMA IN A TEENAGE GIRL Meredith M. Nichols. Cleveland Clinic, Cleveland, OH, USA

MEDIASTINAL GREY ZONE LYMPHOMA IN A 15-YEAR-OLD FEMALE Corey S. Post, Anamarija M. Perry. Michigan Medicine, Ann Arbor, MI, USA

MEDIASTINAL GREY ZONE LYMPHOMA IN A 19 YEAR OLD MALE Haipeng Shao. H Lee Moffitt Cancer Center, Tampa, FL, USA

9:50

INTRODUCTION.

9:55

PEDIATRIC-TYPE FOLLICULAR LYMPHOMA WITH MARGINAL ZONE DIFFERENTIATION Leticia Quintanilla-Fend. University Hospital Tuebingen, Tuebingen, Germany

10:07

PROMINENT REACTIVE MARGINAL ZONE EXPANSION IN A PEDIATRIC TESTICULAR FOLLICULAR LYMPHOMA Simon Nicoletti1, Pierre Isnard1, 2, Omer Beganovic3, Sophie Kaltenbach3, Amaury Leruste4, Alaa Cheikhelard5, Sabine Sarnacki5, 2, Vahid Asnafi3, 2, Julie Bruneau1, 2, Thierry Jo Molina1, 2. 1Department of pathology, APHP, Necker Hospital, Paris, France. 2 Paris Cité University, Paris, France. 3Laboratory of Oncohematology, APHP, Necker Hospital, Paris, France. 4Department of Pediatric Oncology, Curie Institute, Paris, France. 5Department of Pediatric Surgery, APHP, Necker Hospital, Paris, France

10:19

EXTRANODAL PEDIATRIC FOLLICULAR LYMPHOMA  Patricia Arboleda Ezcurra1, Ahmed Ayad 1, Caitlin Harmon 1, Vrinda Shenoy 1, Duffield Amy2, Hussein Shafinaz2, Salib Christian 2. 1Mount Sinai West, NY, NY, USA. 2Mount Sinai Hospital, NY, NY, USA

10:31

SUMMARY OF SUBMITTED CASES IN THIS CATEGORY.

FOLLICULAR LYMPHOMA PRESENTING AS A CONJUNCTIVAL LESION IN A PEDIATRIC PATIENT Bhawana Adhikari, MD, Ginell Post, MD, Vijay M Patel, MD. University of Arkansas for Medical Sciences, Little Rock, AR, USA

PEDIATRIC MONOCLONAL GAMMOPATHY OF UNDETERMINED SIGNIFICANCE (MGUS) Ahmed Ayad1, Matan Kadosh1, Oumaima Outani4, Patricia Arboleda Ezcurra1, Joshua Richter3, Alina Dulau Florea2, Amy Duffield2. 1Department of Pathology, Icahn School of Medicine at Mount Sinai, Mount Sinai West Hospital, New York, NY, USA. 2Department of Pathology, Icahn School of Medicine at Mount Sinai, Mount Sinai Hospital, New York, NY, USA. 3Department of Hematology and Medical Oncology, Icahn Medicine at Mount Sinai, Mount Sinai Hospital, New York, NY, USA. 4Mohamed V Faculty of Medicine and Pharmacy, Rabat Morocco

18-YEAR-OLD FEMALE WITH PEDIATRIC-TYPE FOLLICULAR LYMPHOMA WITH MARGINAL ZONE DIFFERENTIATION Jiani Chai1, Chandler Sy1, Ivo Sahbandar1, Georgi Lukose1, Nitya Gulati2, Madhu Ouseph1. 1Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA. 2Department of Pediatrics, Weill Cornell Medicine, New York, NY, USA

PRIMARY OVARIAN MARGINAL ZONE LYMPHOMA IN 17 YEAR OLD Amy M Coffey, Chandra Krishnan, George Huang. University of Texas Dell Medical School, Austin, TX, USA

A MEDIAL CANTHUS MARGINAL ZONE LYMPHOMA: THE BORDERLAND BETWEEN CUTANEOUS AND EXTRANODAL MARGINAL ZONE LYMPHOMAS Nadine Demko, Van-Hung Nguyen, René P. Michel. McGill University, Montréal, QC, Canada

INDOLENT EXTRANODAL MARGINAL ZONE LYMPHOMA IN AN ADOLESCENT MALE WITH SUBSEQUENT UNRELATED SUBCUTANEOUS CLASSICAL HODGKIN LYMPHOMA. Russell K Dorer1, 2. 1Virginia Mason Franciscan Health, Seattle, WA, USA. 2University of Washington, Seattle, WA, USA

PEDIATRIC FOLLICULAR LYMPHOMA WITH A MUTATIONAL PROFILE AKIN TO ADULT ONSET FOLLICULAR LYMPHOMA Giby V George1, Malgorzata Kajstura1, W Richard Burack1, Siba El Hussein2. 1Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, USA. 2Department of Pathology, University of Vermont, Burlington, VT, USA

PEDIATRIC-TYPE FOLLICULAR LYMPHOMA ARISING IN THE PAROTID GLAND OF A TWO-YEAR-OLD CHILD Anindita Ghosh, Peter Waynes, Xenia Parisi, Xu Jie, L. Jeffrey Medeiros. MD Anderson Cancer Center, Houston, TX, USA

YOUNG ADULT WITH A T(14;18)-NEGATIVE FOLLICULAR/FOLLICLE CENTER ORIGIN B-CELL LYMPHOMA INVOLVING THE FEMALE GENITAL TRACT. Caitlin Harmon1, Mohamed Rabie1, Faryal Fatima1, Patricia Arboleda1, Matan Kadosh1, Christian Salib2, Bruce Petersen2, Dalia Abdel-Azim2, Alina Dulau-Florea2, Amy Duffield2, Shafinaz Hussein2. 1Mount Sinai West Hospital, Icahn School of Medicine, New York, NY, USA. 2Mount Sinai Hospital, Icahn School of Medicine, New York, NY, USA

PEDIATRIC-TYPE FOLLICULAR LYMPHOMA WITH EXTENSIVE MARGINAL ZONE DIFFERENTIATION Clarissa E. Jordan1, Rebecca L. King1, Theodore Schultheiss2, Daniel P. Larson1. 1Mayo Clinic, Rochester, MN, USA. 2Northern Arizona Healthcare, Flagstaff Medical Center, Flagstaff, AZ, USA

AN UNUSUAL PATTERN OF PEDIATRIC-TYPE FOLLICULAR LYMPHOMA Matthew Xi Luo1, Renee Zhang1, Keith Loeb1, 2, Kikkeri N Naresh1, 2, Xueyan Chen1, 2. 1University of Washington, Seattle, WA, USA. 2Fred Hutch Cancer Center, Seattle, WA, USA

PEDIATRIC-TYPE FOLLICULAR LYMPHOMA WITH PERSISTENT B-SYMPTOM Vidya Nagrale1, Neerja Vajpayee2, Mihai Merzianu1. 1Roswell Park Comprehensive Cancer Center, Department of Pathology, Buffalo, NY, USA. 2Oneida Health, Oneida . 3Roswell Park Comprehensive Cancer Center, Department of Pathology, Buffalo

A RARE CASE OF PRIMARY TESTICULAR FOLLICULAR LYMPHOMA IN A PEDIATRIC PATIENT Amanda J. Nguyen1, Clarissa E. Jordan1, Rebecca L. King1, David S. Viswanatha1, Jess F. Peterson1, Nina Rahimi2, Cody J. Artymiuk1, Ellen D. McPhail1. 1Mayo Clinic, Rochester, MN, USA. 2Long Beach Memorial Pathology, Long Beach, CA, USA

A  RARE CAUSE OF RECURRENT ANEMIA IN AN ADOLESCENT  Dingani Nkosi1, Elizabeth Kagotho2, Patricia Okiro2, Nancy Okinda2, Aliyah R Sohani1. 1Mass General Brigham, Boston, MA, USA. 2Aga Khan University Hospital, Nairobi, Kenya

14-YEAR-OLD MALE WITH PEDIATRIC NODAL MARGINAL ZONE LYMPHOMA Chandler Sy, Georgi Lukose, Jiani Chai, Ivo Sahbandar, Madhu Ouseph, Julia Geyer. NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, USA

MALT LYMPHOMA IN A 9-YEAR-OLD FEMALE PRESENTED AS A COLON MASS Yu Yang. University of Florida, Gainesville, FL, USA

WHAT’S IN A NAME? THAT WHICH I CALL EBV-LPD, BY ANY OTHER NAME IS STILL AN ENIGMA Ashish Kumar. Cincinnati Children's Hospital Medical Center

12:30

INTRODUCTION.

12:35

A RARE CAUSE OF HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS Claudio A. Mosse. Vanderbilt University Medical Center, Nashville, TN, USA

12:47

HEPATOSPLENIC T-CELL LYMPHOMA MASQUERADING AS HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS Vinay Sakaleshpura Mallikarjuna1, Robert Lorsbach2. 1University of Cincinnati College of Medicine, Cincinnati, OH, USA. 2Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA

12:59

FULMINANT EBV-ASSOCIATED INFECTION WITH SECONDARY HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS Lili Guo1, Mihai Merzianu1, 2. 1Department of Pathology and Anatomical Sciences, University at Buffalo, Buffalo, NY, USA. 2Department of Pathology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA

1:11

MARROW INVOLVEMENT BY MYCOBACTERIUM GENAVENSE INFECTION IN A PATIENT WITH STAT1 GAIN OF FUNCTION MUTATION Joel Raqueno, Rakshit Tyagi, Sheeja T. Pullarkat. UCLA Medical Center, Los Angeles, CA, USA

1:23

HISTIOCYTOSIS IN THE BONE MARROW- A DIFFICULT DIAGNOSIS. Lakshmi Venkatraman, Michelle Moore. Dept of Cellular Pathology, Belfast Health and Social Care Trust, BELFAST, United Kingdom

1:35

JUVENILE XANTHOGRANULOMA WITH CDKN2A LOSS: A HISTIOCYTIC NEOPLASM OF UNCERTAIN MALIGNANT POTENTIAL? Aishwarya Ravindran1, Jason Wicker2, Alyssa Lee1, Matthew Kutny 3, Gaurav Goyal4. 1Department of Pathology (Hematopathology), University of Alabama at Birmingham, Birmingham, AL, USA. 2Division of Pediatric Pathology, Children’s of Alabama, University of Alabama at Birmingham, Birmingham, AL, USA. 3Division of Pediatric Hematology-Oncology, University of Alabama at Birmingham, Birmingham, AL, USA. 4Division of Hematology-Medical Oncology, University of Alabama at Birmingham, Birmingham, AL, USA

1:47

CLINICAL AND HISTOLOGICAL PROGRESSION IN PEDIATRIC ROSAI-DORFMAN DISEASE  Sam Sirotnikov1, Jinjun Cheng2, Rajeswari Jayakumar3, Sunita Park4. 1Childrens National Hospital, Washington, DC, USA. 2Mayo Clinic, Phoenix, AZ, USA. 3Virginia Commonwealth University, Richmond, VA, USA. 4Children's Healthcare of Atlanta, Atlanta, GA, USA

1:59

SECONDARY MALIGNANT HISTIOCYTIC NEOPLASM (HISTIOCYTIC SARCOMA) IN AN 8-YEAR-OLD FEMALE OCCURRING DURING B-LYMPHOBLASTIC LEUKEMIA MAINTENANCE CHEMOTHERAPY Karen M Chisholm1, Jennifer Picarsic2, Lauren Kroll-Wheeler1, Sandra D. Bohling1. 1Seattle Children's Hospital, Seattle, WA, USA. 2Cincinnati Children's Hospital, now at University of Pittsburgh School of Medicine, Pittsburgh, PA, USA

2:11

SUMMARY OF SUBMITTED CASES IN THIS CATEGORY.

SOLITARY LANGERHANS CELL HISTIOCYTOMA IN INFANCY: A CASE STUDY Michele R. Anderson, Rajeswari Jayakumar, Justin B. Dalton. VCUHS, RICHMOND, VA, USA

PEDIATRIC LARYNGEAL ROSAI-DORFMAN DISEASE Ahmed Ayad1, Faryal Fatima1, Oumaima Outani4, Patricia Arboleda Ezcurra1, Jodi Sassoon3, Amy Duffield2. 1Department of Pathology, Icahn School of Medicine at Mount Sinai, Mount Sinai West Hospital, New York, NY, USA. 2Department of Pathology, Icahn School of Medicine at Mount Sinai, Mount Sinai Hospital, New York, NY, USA. 3Department of Pathology, Icahn School of Medicine at Mount Sinai, New York Eye and Ear Infirmary of Mount Sinai, New York, NY, USA. 4Mohamed V Faculty of Medicine and Pharmacy, Rabat Morocco

FAMILIAL HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS TYPE 3 WITH BIALLELIC LOSS-OF-FUNCTION VARIANTS IN UNC13D.   Haley Brown1, Mark Steele1, D. Brian Dawson2, Ashley Eckel3, Melissa Stalling1. 1Akron Children's Hospital, Akron, OH, USA. 2Cincinnati Children's Hospital, Cincinnati, OH, USA. 3Hematologics, Inc, Seattle, WA, USA

ALK+ HISTIOCYTOSIS PRESENTING AS MARKED PANCYTOPENIA IN A 20-MONTH-OLD WITH BILATERAL RENAL MASSES Karen M Chisholm1, Erin R. Rudzinski1, 2, Sandra D. Bohling1. 1Seattle Children's Hospital, Seattle, WA, USA. 2now at Indiana University School of Medicine, Indianapolis, IN, USA

AN UNUSUAL CASE OF PERSISTENT ROSAI-DORFMAN DISEASE Heidi Christian, Steven Garzon, Ameet Kini. University of Illinois Hospital and Health Sciences System, Chicago, IL, USA

ALK-POSITIVE HISTIOCYTOSIS PRESENTING AS EYELID, SKIN, LUNG, RENAL AND OVARIAN LESIONS IN AN INFANT Hannah Cutshall MD, Rodolfo Henrich Lobo MD. University of Arkansas for Medical Sciences, Little Rock, AR, USA

PERSISTENT/REFRACTRORY ROSAI-DORFMAN DISEASE J. Elliott Denney, Claudio Mosse, Emily Mason. Vanderbilt University Medical Center, Nashville, TN, USA

ROSAI-DORFMAN DISEASE IN A 2-YEAR-OLD PATIENT Lorant Farkas1, Stefanie M Hansen1, Marius Lund-Iversen1, Jose LS Camacho2. 1Oslo University Hospital, Oslo, Norway. 2Akershus University Hospital, Loerenskog, Norway

FULMINANT EPSTEIN-BARR VIRUS (EBV) INFECTION WITH HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (HLH) AND PROBABLE X-LINKED LYMPHOPROLIFERATIVE DISEASE (XLP) Nea Fride1, Daniel Robbins2, Jessica Gulliver1, Eduard Matkovic1, Daniel R Matson1, Katryn Furuya3, Jamie Kallan1, Catherine Bodnar1. 1University of Wisconsin School of Medicine and Public Health Department of Pathology, Madison, WI, USA. 2Children's Mercy, Kansas City, MO, USA. 3University of Wisconsin School of Medicine and Public Health Department of Pediatrics, Madison, WI, USA

CNS INVOLVEMENT BY ROSAI-DORFMAN DISEASE (RDD) RADIOGRAPHICALLY MIMICS GLIONEURONAL TUMOR May Fu1, Dehua Wang1, 2, Jun Qin Mo1, 2. 1University of California, San Diego, San Diego, CA, USA. 2Rady Children's Hospital, San Diego, CA, USA

FAMILIAL HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS WITH MUNC13-4 MUTATIONS Juli-Anne Gardner, Heather Bradeen. University of Vermont Medical Center, Burlington, VT, USA

ALK-POSITIVE HISTIOCYTOSIS WITH KIF5B::ALK FUSION PRESENTING AS A NASAL MASS IN A 10-YEAR-OLD Rohiverth Guarecuco Jr. 1, 4, Yousef Soofi2, Mihai Merzianu3, Marian H. Harris4, Jacob R. Bledsoe4. 1Mass General Brigham, Boston, MA, USA. 2Erie County Medical Center, Buffalo, NY, USA. 3Roswell Park Cancer Center, Buffalo, NY, USA. 4Boston Children's Hospital, Boston, MA, USA

EXTRA CAVITARY PRIMARY EFFUSION LYMPHOMA IN A YOUNG AND IMMUNOCOMPROMISED PATIENT COMPLICATED BY COVID 19 AND HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS Shaniza Haniff1, Jessica Grover2, Matthew Cortese3, Jayalakshmi Balakrishna4. 1Mercy Hospital of Buffalo, Buffalo, NY, USA. 2University of Buffalo, Buffalo, NY, USA. 3Roswell Park Cancer Center, Buffalo, NY, USA. 4Roswell Park Cancer Center, Buffalo, NY, USA

ALK POSITIVE HISTIOCYTIC PROLIFERATION WITH A DCTN1::ALK FUSION Shahad M. Iqneibi, Yeon-Whan Choe, Saja K. Asakrah, Sandra G. Gjeorgjievski. EMORY UNIVERSITY, Atlanta, GA, USA

A CASE OF LANGERHANS CELL HISTIOCYTOSIS WITH ATYPICAL MORPHOLOGIC AND IMMUNOPHENOTYPIC FEATURES Christine W Kahlow1, Sharon K Germans1. 1UT Southwestern Medical Center, Dallas, TX, USA. 2UT Southwestern Medical Center, Dallas, TX, USA

DIFFUSE LARGE B-CELL LYMPHOMA WITH EXTENSIVE LYMPHOHISTIOCYTIC INFILTRATE Justin Kelley, Nicolas Lopez-Hisijos. Vanderbilt University Medical Center, Nashville, TN, USA

A CASE OF SYSTEMIC JUVENILE XANTHOGRANULOMA WITH TFG::RET FUSION Jingwei Li1, Ashish Kumar2, Robert Lorsbach1. 1Division of Pathology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA. 2Division of Bone Marrow Transplantation & Immune Deficiency, Cincinnati, OH, USA

HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (HLH) IN A 16 YEAR-OLD PATIENT DIAGNOSED OF INFECTIOUS MONONUCLEOSIS 3 WEEKS AGO Yen-Chun Liu. St. Jude Children's Research Hospital, Memphis, TN, USA

INHERITED SYNDROME WITH ATYPICAL FEATURES IN A 2-MONTH-OLD MALE Brian Lockhart1, Elizabeth Margolskee1, 2, Gerald Wertheim1, 2, Michele Paessler1, 2. 1Children's Hospital of Philadelphia, Philadelphia, PA, USA. 2University of Pennsylvania, Philadelphia, PA, USA

S100 POSITIVE HISTIOCYTES: NOT JUST ROSAI-DORFMAN DISEASE ANYMORE Elizabeth Margolskee1, 2, Angela Vaiene1, 2. 1Children's Hospital of Philadelphia, Philadelphia, PA, USA. 2Hospital of the University of Pennsylvania, Philadelphia, PA, USA

PERIPHERAL T-CELL LYMPHOMA, NOT OTHERWISE SPECIFIED, IN A ROBUST HISTIOCYTIC BACKGROUND, AN UNUSUAL PRESENTATION WITH POTT’S-PUFFY TUMOR. Margaret Moore, Nadine Aguilera. University of Virginia Health, Charlottesville, VA, USA

ALK-POSITIVE HISTIOCYTOSIS WITH A KIF5B:: ALK FUSION Okechukwu V Nwogbo, James Cook, Steven Billings, Brian Rubin, John Goldblum, Karen Fritchie. Cleveland Clinic, Cleveland, OH, USA

SYSTEMIC EPSTEIN BARR VIRUS (EBV) POSITIVE T-CELL LYMPHOMA OF CHILDHOOD WITH PROMINENT HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS Ifeomachukwu E Nwosu, Deborah A Fuchs, Holly E Pariury. Banner University Medical Center/University of Arizona, Tucson, AZ, USA

BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM WITH KRAS MUTATION AND MULTIPLE TSG DELETIONS Dennis P O'Malley, Malcolm Tran, Skyler Stephan, Jennifer Hummel. NeoGenomics, Aliso Viejo, CA, USA

CD30-NEGATIVE RELAPSE OF ALK-POSITIVE ANAPLASTIC LARGE CELL LYMPHOMA AFTER BRENTUXIMAB VEDOTIN​ Xenia Parisi, Jie Xu, Wei Wang, Shimin Hu, Vasiliki Leventaki, Sanam Loghavi, Iman Sarami. The University of Texas MD Anderson Cancer Center, Houston, TX, USA

CD15 EXPRESSION IN DIFFUSE LARGE B-CELL LYMPHOMA MAY CAUSE DIAGNOSTIC CONFUSION Xenia Parisi, Guilin Tang, Mark J. Routbort, Carlos E. Bueso-Ramos, L. Jeffrey Medeiros. The University of Texas - MD Anderson Cancer Center, Houston, TX, USA

LANGERHANS CELL HISTIOCYTOSIS IN A 7-YEAR-OLD BOY Marcello Pecoraro Toscano, Anna B. Owczarczyk. Cleveland Clinic, Cleveland, OH, USA

HISTIOCYTIC SARCOMA TRANSDIFFERENTIATING FROM T-LYMPHOBLASTIC LEUKEMIA  Aishwarya Ravindran1, Alexander Mackinnon2, Gaurav Goyal3. 1Department of Pathology (Hematopathology), University of Alabama at Birmingham, Birmingham, AL, USA. 2Division of Genomics Diagnostics and Bioinformatics, University of Alabama at Birmingham, Birmingham, AL, USA. 3Division of Hematology-Medical Oncology, University of Alabama at Birmingham, Birmingham, AL, USA

PEDIATRIC ERDHEIM-CHESTER DISEASE Karen Rech, Dragan Jevremovic. Mayo Clinic, Rochester, MN, USA

JUVENILE XANTHOGRANULOMA OF THE THORACIC SPINAL CORD WITH FNBP1-BRAF FUSION Karen L Rech. Mayo Clinic, Rochester, MN, USA

ALK+ HISTIOCYTOSIS Lauren Reiman1, Debra Hawes1, 2, Jianling Ji1, 2, Jennifer Picarsic3, Alexandra E. Kovach1, 2. 1Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. 2Department of Pathology, Children’s Hospital Los Angeles, Los Angeles, CA, USA. 3Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

22-YEAR-OLD MALE WITH A HISTORY OF RECURRENT AND MULTISYSTEM LANGERHANS CELL HISTIOCYTOSIS AND THERAPY-RELATED MYELODYSPLASTIC SYNDROME Ivo N. Sah Bandar, Georgi Lukose, Chandler Sy, Cynthia Magro, Amy Chadburn. Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA

3-YEAR-OLD MALE WITH ALK-POSITIVE HISTIOCYTOSIS PRESENTING WITH A SUBGLOTTIC MASS Ivo N. Sah Bandar1, Nitya Gulati2, Theresa Scognamiglio1, Madeline Drusin3, Hannah Rosen3, Paul D. Barone1, Amy Chadburn1. 1Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA. 2Department of Pediatrics, Weill Cornell Medicine, New York, NY, USA. 3Department of Otolaryngology- Head and Neck Surgery, Weill Cornell Medicine, New York, NY, USA

ROSAI-DORFMAN DISEASE OF THE BREAST Richard Shao1, Jinming Song2. 1The University of Central Florida College of Medicine, Orlando, FL, USA. 2H Lee Moffitt Cancer Center, Tampa, FL, USA

MULTISYSTEMIC ROSAI DORFMAN DISEASE - A STORY OF DISEASE EVOLUTION Tanuja Shet1, Uma Sakhadeo2, Nirmalaya Moulick3, Chetan Dhamne 3. 1Professor and Head Dept of Pathology, Tata memorial hospital, Mumbai India. 2Professor and pathologist Dept of Pathology, Tata Memorial Hospital India, Mumbai India. 3Professor Pediatric Oncology, Tata Memorial Center, Mumbai India

ROSAI-DORFMAN DISEASE WITH DIFFUSE BILATERAL CERVICAL LYMPHADENOPATHY Ping Shi, Eman Sallam, Erik Washburn, Michael G. Bayerl. Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA

CONGENITAL LANGERHANS CELL HISTIOCYTOSIS Mark A. Steele. Akron Children's Hospital, Akron, OH, USA

HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (HLH) WITH CLONAL ABERRANT EBV POSITIVE T CELLS Joseph Stenberg, Daniel Babu. University of New Mexico Health Sciences Center, Albuquerque, NM, USA

NODAL PRESENTATION OF LANGERHANS CELL HISTIOCYTOSIS Miekan Stonhill, Aliyah Sohani, Judith Ferry. Massachusetts General Hospital, Boston, MA, USA

3-YEAR-OLD MALE WITH MULTISYSTEM LANGERHANS CELL HISTIOCYTOSIS Chandler Sy, Jiani Chai, Ivo Sahbandar, Georgi Lukose, Julian Willett, Nitya Gulati, Cynthia Magro, Amy Chadburn. NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, USA

SOLITARY XANTHOGRANULOMA OF SALIVARY GLAND: FIRST CASE WITH MOLECULAR CHARACTERIZATION Raghad Tallab1, Alecia Young1, 2, Mihai Merzianu1. 1Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA. 2University at Buffalo, Buffalo, NY, USA

SPINDLE CELL SARCOMA OF HEMATOLOGIC ORIGIN: FOLLICULAR DENDRITIC CELL SARCOMA OF YOUNG ADULT Nichthida Tangnuntachai. Chulalongkorn University, Bangkok Thailand

ALK-POSITIVE HISTIOCYTOSIS CLINICALLY MIMICKING A METASTATIC MALIGNANCY Jeffrey Thomas1, Michael Daniel2, Amy Ku3, Criag Soderquist4, Bachir Alobeid5, Govind Bhagat6. 1Columbia University Irving Medical Center, New York City, NY, USA. 2Columbia University Irving Medical Center, New York City, NY, USA. 3Columbia University Irving Medical Center, New York City, NY, USA. 4Columbia University Irving Medical Center, New York City, NY, USA. 5Columbia University Irving Medical Center, New York City, NY, USA. 6Columbia University Irving Medical Center, New York City, NY, USA

INCONSPICUOUS EMPERIPOLESIS: A CASE OF SUBTLE EXTRANODAL ROSAI-DORFMAN DISEASE Ashley K Volaric, Brittney Boles, Joanna L Conant, Katherine Devitt, Juli-Anne Gardner, Sakshi Jasra, Ronald Bryant, John C Dewitt. University of Vermont Larner College of Medicine, Burlington, VT, USA

A RARE CASE OF MULTISYSTEM LANGERHANS CELL HISTIOCYTOSIS AND CUTANEOUS EXTRAMEDULLARY HEMATOPOIESIS IN A NEWBORN PRESENTING AS BLUEBERRY MUFFIN BABY SYNDROME Julian DS Willett1, Georgi Lukose1, Taylor Kalomeris1, Nitya Gulati2, Jaclyn Rosenzweig2, Alexander Chou2, Amy Chadburn1, Cynthia Magro1. 1Pathology & Laboratory Medicine, NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, USA. 2Pediatric Hematology/Oncology, NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, USA

LANGERHANS CELL HISTIOCYTOSIS WITH PRECEDING EBV-ASSOCIATED HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (HLH) Penny Wright1, Tristan Pettit2. 1Canterbury Health Laboratories, Christchurch, New Zealand. 2Christchurch Hospital, Christchurch, New Zealand

ALK+ HISTIOCYTOSIS WITH INDOLENT T-LYMPHOBLASTS PROLIFERATION (IT-LBP) Yu Yang. University of Florida, Gainesville, FL, USA

JUVENILE NON LANGERHANS CELL HISTIOCYTOSIS WITH XANTHOGRANULOMATOUS FEATURES OCCURRING IN THE SETTING OF AN AUTOINFLAMMATORY SYNDROME Jenny Zhang, Sarah Gradecki, Ifeyinwa E Obiorah. University of Virginia Health system, Charlottesville, VA, USA

CLOSING REMARKS Michele Paessler, David Grier, Alexandra Kovach, Robert Lorsbach.