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Pauline M. Chou, M.D Professor of Pathology Ann and Robert H. Lurie Children s Hospital Lurie Cancer Center Northwestern University Feinberg School of Medicine, Chicago European Congress, Sept. 2018

Introduction Needle biopsies are underutilized in pediatric tumors in the US The reason is multifactorial: Pediatric tumors are rare and diagnostically challenging as many have overlapping morphologic features With few exceptions, most pediatric pathologists are not trained in cytopathology. In addition, COG protocols requires large tissue samples and discourages needle biopsies Sköldenberg EG, et al. J Pediatr Surg. 2002 Silverman JF, et al. Am J Clin Pathol. 1991 Drut R, et al. J Pediatr Hematol Oncol. 2005 Monaco SE, Teot LA. Cancer Cytopathol 2014

Introduction Recently there are a number of reports attributing to the safety and diagnostic accuracy of needle biopsies in bone and soft tissue lesions including children Current trend is to approach diagnosis using minimal invasive techniques We are required to do more with less Khalbuss et al 2010; Interiano RB, et al. 2016 Yu G. et al; Diagnostic Cytopathol 2017 Ziv E., et al. Cancer J 2016

Molecular medicine: key points Childhood tumors are different. Childhood tumors tend to show more genomic changes such as copy number alterations, gene amplifications, chromosomal breaks and gene fusions Tumors typically have small mutational burden but develop along several evolutionary trajectories within the same tumor or that occur across metastasis or during relapse These findings underscore the importance of needle biopsies as recurrent or metastatic tumors tend to be genetically distinct from primary tumors Hence for personalized treatment strategy, we anticipate more needle biopsies in future. training in cyto-histopathology and molecular pathology Ziv. 2016, Karrlson 2018 Triche T. the Pathologist 2018 5

Data from our past experience 185 biopsies were performed between 1993 and 1998 141 were for initial diagnosis of which 47% were for primary tumor, 29% to rule out metastasis and 24% at follow-up to rule out relapse/infection Overall satisfactory results in 82% 18% unsatisfactory-includes erroneous diagnosis at ROSE or had additional surgical biopsy (including those that were driven by clinicians without allowing time to perform ancillary studies 4 false negative (IMT, Fibrosarcoma, hemangioendothelioma and LCH) and 1 false positive (Nephroblastomatosis) Tucker R, Chou PM. Lab invest 79:6p, 1999 6

In contrast We performed 123 biopsies for primary diagnosis in 2015, 153 in 2016 (30%) and 171 in 2017 (18% increased) *Others: mediastinum, parotid, kidney, liver and lymph node Unsat 2 bone sampling error, and one spleen IMT

Diagnosis is key Certain tumors are more prevalent in children but adult type malignancies can also be seen as well Establishing correct diagnosis require a team approach: clinical colleagues, radiologists, surgeons, oncologists Key cyto-histologic and immunohistochemical features and ancillary molecular studies

Case #1 8 year old male Presented with a 1-year history of R heel pain No other symptoms Diagnosis: plantar fasciitis Later seen at an Ortho clinic Xray R foot was read as abnormal (likely osteomyelitis or primary bone tumor) Subsequent MRI showed soft tissue mass concerning for malignancy

Hypercellular smears with monotonous hyperchromatic cells and scant occasional vacuolated cytoplasm (best on Diff Quik) The nuclei have evenly dispersed fine chromatin with indistinct nucleoli

Tumor histology IHC ES/PNET Small round cells CD99, NSE or neural, Cytokeratins +/- Alveolar RMS Mesenchymal chondrosarcoma Synovial sarcoma, monophasic Alveolar/solid, wreath-like Giant cells Small cells, mottled calcifications, cartilage Oval cells, molding focal whorled pattern Desmin, myogenin, CD99 positive or negative Sox 9, CD99, desmin CD99, EMA, CK, TLE-1, ATF2 Neuroblastoma Neuropil, ganglion cell Phox2B, synaptophysin, NB84, CD99- Desmoplastic SRBC Malignant rhabdoid tumor Nests of tumor cells+ desmoplastic stroma Rhabdoid like with perinuclear inclusions, vesicular nuclei Myogenic, neural epithelial, CD99 +/- Vimentin, EMA, CK, SMA, CD99, synaptophysin, BAF47 Undifferentiated sarcoma Primitive oval to round cells occasionally spindled No specific lineage, CD99 diffuse or patchy positivity

EWSR1 is implicated in numerous tumors 14

Neoplasm Genetic abnormality Chromosome alterations Fusion gene Ewing family Ewing-like sarcoma Undifferentiated round cell sarcoma Desmoplastic round cell tumor Mesenchymal chondrosarcoma Alveolar rhabdomyosarcoma Extraskeletal myxoid chondrosarcoma EWSR1 to ETS fusion FUS to ETS fusion BCOR-CCNB3 EWSR1-NFATc2 translocation t(11;22)(q24;q12); t(21;22)(q22;q21); t(7;22)(q22;q24) t(16;21)(p11;q22); t(2;16)(q35;q11) inv(x)(p11.4p11.2) Complex rearrangement leading to amplification of translocated segment with ring chromosome formation EWSR1-FLI1 EWSR1-ERG EWSR1-ETV1 FUS-ERG FUS-FEV BCOR-CCNB3 EWSR1-NFATc2 CIC-DUX4 t(4;19)(q35;q13) t(10;19)(q26;q13) CIC-DUX4 EWSR1-WT1 t(11;22)(p13;q12) EWSR1-WT1 HEY1-NCOA2 fusion inv(8)(q13;q21) HEY1-NCOA2 FOXOA1 fusion t(2;13)(q35;q14) PAX3-FOXOA1 PAX7-FOXOA1 NR4A3 fusion to TET t(9;22)(q22;q12) t(9;17)(q22;q11) EWSR1-NR4A3 TAF2N-NR4A3 Synovial sarcoma SYT fusion t(x;18)(p11;q11) SYT-SSX1, SSX2 Katjtiar et al 2013 15

Our case was diffusely CD99 positive Negative for all other markers FISH for EWSR1 and RT/PCR for the most common translocation: EWSR1-FLI1 and EWSR1-ERG, EWSR1-WT1 and CIC-DUX were negative Additional study: a complex rearrangement of EWSR1 leading to amplification with ring chromosome formation DIAGNOSIS: EWING-LIKE SARCOMA

Triaging for spindle cell tumor Often more challenging While most are benign, sarcomas still account for up to 7% of malignancies in young children Touch imprints: establish cell lineage, namely vascular, myofibroblastic/fibroblastic or myogenic Specific diagnosis: team approach incorporating histology, clinical parameters and imaging studies

Case 2: 4 month old infant with an axillary mass, present since birth. She had no significant medical history. Physical examination: A 2 cm smooth, well-defined soft mass on the right lateral chest wall at lower border of the axilla with no tenderness, redness or drainage from the area. Ultrasound examination revealed a cyst in the subcutaneous region, consistent with lymphangioma.

During the procedure copious amount of blood was drained causing a decreased in size: supportive of a vascular lesion Touch imprints: Monotonous spindle cells Nuclei: elongated with rounded ends, finely dispersed chromatin Nucleoli inconspicuous

Cellular spindle cells with few admixed inflammatory cells (lymphocytes and plasma cells). The spindle cells were mildly pleomorphic without particular architectural arrangement. Mitotic figures were rare. 20

List of IHC and fusion transcripts Spindle cell tumors IHC Genetics Diagnosis Alk ALK IMT CD34, Vimentin COL1A1-PDGFB t(17;22)(q21;q13) DFSP CD68, CD99, desmin EWSR1-ATF/ EWSR1-CREB1 t(12;22), (2:22) Angiomatoid fibrous histiocytoma Vimentin ETV6-NTRK3 t(12;15)(p13;q25) Infantile fibrosarcoma Bcl2, cytokeratins, EMA, CD99 Vimentin, MUC4 SYT-SSX1/SSX2/SSX4 t(x;18) FUS-CREB3L2 t(7;16) and FUS- CREB3L1 t(11;16) Synovial Sarcoma Low grade fibromyxoid sarcoma 21

ETV6-NTRK3: 69bp 22

Infantile Fibrosarcoma IFS: a mimicker of vascular malformation Most IFS show recurrent ETV6/NTRK3 gene fusions, sensitive to chemotherapy with an overall favorable clinical outcome Recent studies have shown the ETV6/NTRK3 fusion negative IFS, or IFS-like tumors in older children have BRAF gene rearrangements or related fusions. A number of unclassifiable spindle cell sarcomas have been associated with NTRK1 IFS that lacks ETV6/NTRK3 may benefit from testing for BRAF, NTRK1 and Met. Hu et al., 2015; Kao Y-C, et al. 2017 23

Case 3. 5 year-old with history of pneumonia and left pleural effusion She was found to have a 7.5 x 6.5 x 7cm solid mass in LUL

Desmin Positive: Vimentin Desmin Myogenin, MyoD1 Negative: Epithelial markers Differential diagnosis 1. Embryonal Rhabdomyosarcoma 2. Ewing s Sarcoma (chest wall based) 3. Synovial sarcoma (after 7 years) 4. Pleuro-pulmonary blastoma (type III) Molecular study was negative for FOXOA1, EWSR and SYT Evaluation for DICER1: germline DICER1 (pathogenic variant) Myogenin Diagnosis: Pleuropulmonary Blastoma type III

Tumor syndromes A major challenge, particularly germane to pediatric pathologist is that tumor development may precede recognition of a syndrome With few exceptions (Beckwith-Wiedemann, hemihypertrophy), most patients lack recognizable phenotype Consequence of diagnosing TPS: adjust chemotherapy, surveillance program for screening other associated malignancies, genetic counselling for family members Postema et al. Pediatr Blood Cancer 2017

Childhood tumors with high probability of being part of predisposition syndrome Tumor Associated syndromes Incidence % Adrenocortical Ca Li-Fraumeni S., Beckwith-Wiedemann S 52, 7 ATRT Rhabdoid predisposition Syndrome 24 Choroid plexus Ca Li-Fraumeni Syndrome 55 CMML, JMML Neurofibromatosis type 1 14, 12 Desmoid tumor Familial adenomatous polyposis 14 Hemangioblastoma Von Hippel Lindau Syndrome 33 Hepatoblastoma Familial adenomatous polyposis 6 Malignant melanoma Xeroderma pigmentosum 7 MPNST Neurofibromatosis type 1 25 Medulloblastoma (<3) Li-Fraumeni S (Gorlin S) 5, 4 Meningioma Neurofibromatosis type 2 12 Myelodysplastic S GATA2 spectrum, Fanconi anemia, NF1 7, 7, 2 Nephroblastoma BWS, WAGR S, Isolated hemihyperplasia, Denys-Drash Syndrome 5, 3, 3, 2 Postema et al 2017 28

Childhood tumors with high probability of being part of predisposition syndrome Tumor Associated syndromes % Optic nerve glioma Neurofibromatosis type 1 48 Phaeochromocytoma/ paraganglioma Pineoblastoma, pituitary blastoma, pleuropulmonary blastoma Pituitary adenoma Von Hippel Lindau Syndrome, Familial PC/PGL, MEN, NF type 1 34, 30, 5, 3 PPB family tumor and dysplasia syndrome 29, 82, 66 Familial isolated pituitary adenomas, MEN type i Retinoblastoma, unilateral Retinoblastoma tumor syndrome 13 Rhabdomyosarcoma (<3y) Li-Fraumeni Syndrome 5 Spinal ependymoma Neurofibromatosis type 2, Li-Fraumeni S 9, 6 Osteosarcoma Sarcoma predisposition Li-Fraumeni S, Retinoblastoma, NF1, Rothmund-Thompson S, Werner s S, Bloom S, RAPADILINO S, Diamond-Blackfan anemia DNA repair machinery 17, 7 12, 10, x8, 32, 10, 3, 7-13, 3rpt Postema et al 2017, Jackson et al 2016, Benna et al. 2018 30

Tumors associated with PPB family tumor and dysplasia syndrome Benign Cystic nephroma Multinodular goitre Nasal Chondromesenchymal hamartoma Ovarian stromal tumors: Sertoli Leydig cell tumors, juvenile granulosa cell and gynandroblastomas Malignant Ciliary body medulloepithelioma Thyroid carcinoma (PTC) Botryoid embryonal sarcoma (the uterine cervix, ovary, bladder, biliary tree) Pineoblastoma Pituitary blastoma Rare: Wilms, DICER-related renal sarcoma Schultz 2014, de Kock 2015, Doros 2017, PPB registry website

Bone tumors Two most common bone tumors are Ewing s sarcoma and osteosarcoma. Our challenge is to obtain adequate, quality material for precise diagnosis Find alternative for decal solution-fresh tissue, EDTA, FFPE 33

Future Directions tions Precision medicine starts with pathology- I would add with pediatric pathology A number of advances have been made and a number of precision trials are available globally Basket trials in relapsed/refractory cancers across multiple histologies (results of sequencing used to identify actionable variants), disease-specific precision trials in newly diagnosed patients or disease-specific umbrella trials in relapsed disease Other advances: liquid biopsies and cell free DNA Next gen pathologists : training in cyto-histopathology and molecular pathology Forrest 2018, Fassan M. Arch Pathol Lab Med 2018 Triche T. the Pathologist 2018. COG web 34