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Ultrastructure As An Important Component in Diagnosis of Pediatric Round Cell & Soft Tissue Tumors: Avoiding Pitfalls

John Hicks - Texas Children’s Hospital & Baylor College of Medicine

ACCME/Disclosure

Dr. Hicks has nothing to disclosure

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Differential Diagnosis of Small Round Cell Tumors of Childhood

• Ewing Family of Tumors– Classic, Atypical, PPNET

• Rhabdomyosarcoma– Alveolar & Embryonal

• Neuroblastoma• Lymphoma• Extramedullary ALL/AML• Wilms Tumor• Germ Cell Tumors• Neuroendocrine Tumors• Rhabdoid Tumor• Small Cell Hepatoblastoma

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Differential Diagnosis of Small Round Cell Tumors of Childhood

• Desmoplastic Small Round CellTumor

• Clear Cell Sarcoma of Soft Tissue• Synovial Sarcoma• Alveolar Soft Part Sarcoma• Medulloblastoma – CNS• Mesenchymal Chondrosarcoma• Pleuropulmonary Blastoma• Small Cell Osteosarcoma• Pancreatoblastoma• Sialoblastoma• Small Cell Mesothelioma

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Case History• 37 Week Gestation Male Neonate Delivered

Vaginally • At Delivery, Purple-Blue 8 cm Mass Protruded from

Left Facial/Ear Region• Mass Not Present on Ultrasound at 20 Weeks

Gestation• Diagnostic Imaging and Clinical Impression:

Congenital/Infantile Hemangioma (Vascular Tumor)• Prednisone and Beta-Blocker Therapy Initiated• Tumor Rapidly Increased in Size & Ulcerated• Resection Performed on 8th Day of Life

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Flow Cytometry Results• CD56 (NCAM)• CD38 Positivity• Interpretation:

– Not Compatible with Hematopoietic/Lymphoid Neoplasm

FISH for MYC-N• No Evidence of Amplification

Routine Cytogenetics Pending

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Immunohistochemistry: Negative

• Myogenic– Desmin, Myogenin,

MyoD1• Epithelial

– EMA, Pancytokeratin, CAM 5.2

• Lymphoid– LCA, CD20, CD3, TdT,

CD61, CD31, Myeloperoxidase, CD30, CD43, ALK1, CD4, CD8, CD68, CD1a

• Vascular– CD34, CD31

• Neural– NB84, S100, NFP,

NSE, Chromogranin• Germ Cell

– PLAP, CD30, AFP• Melanocytic

– HMB45, S100 Protein

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CytogeneticsFISH Breakapart Rearrangement of EWSR1• Splitting and Rearrangement of 5’ EWSR1 to

20q11.2 (FISH requested after EM Findings)Conventional Cytogenetics• 50,XY,+6,+12,+15,+17,t(20;22)(q11.2;q12) • 51,idem,+der(22)(t20;22)(q11.2;q12)

Diagnosis• Ewing Sarcoma (Peripheral Primitive

Neuroectodermal Tumor) with Novel t(20;22) EWSR1-NFAT2cTranslocation

NFATc2: (Nuclear Factor of Activated T-Cells,

Cytoplasmic, Calcineurin-Dependent 2)

• Implicated in Breast Cancer & In Cell Motility as Basis for Metastasis

• NFATc2: Pro-Invasive and Pro-Migratory in Breast Cancer

• To Increase Cell Motility NFATc2 Up-Regulates Lipocalin 2 Expression and Modulatse TWEAKR/TWEAK

• NFATc2 Interacts with MEF2D, EP200, IRG48, Protein Kinase M

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• ES/pPNET: 15% Before Age 5 Yrs• 22 Congenital Ewing Sarcoma Cases• 40% - Metastatic Disease (Skin, LN, Brain)• DOD (15 of 22) At 1-24 Months

Small Round Cell Tumors in Neonates• Congenital Ewing Sarcoma Very Rare and Not

Usually in Differential Diagnosis• Ewing Sarcoma Rare Diagnosis in Neonates

and May be Misdiagnosed as Another Small Round Cell Tumor Due to Variable Degrees of Neuroectodermal Differentiation

• Median Age for Ewing Sarcoma: – 15 Yrs of Age– 70% Presenting Before 20 Yrs of Age

• Only 15% of Ewing Sarcomas Diagnosed Before 5 Yrs of Age

Small Round Cell Tumors in Neonates• Differential Diagnosis for Congenital Tumors

include:– Teratoma, Rhabdomyosarcoma– Neuroblastoma – Hemangioma, Other Vascular Tumors – Leukemia, Lymphoma– Langerhans Cell Histiocytosis– Lymphatic Malformations

• Congenital Malignant Tumors Account For Less than 2% of All Childhood Malignancies

• Typical Small Round Cell Tumors Identified During Neonatal Period: Leukemias and Neuroblastomas Most Common (LCH benign)

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Promiscuous Nature of EWSR1

BCOR-CCNB3

Clinical History• 7 year-old healthy boy with painless, nontender

swelling of his right upper thigh noticed 2 months prior to presentation

• Mass recently increased markedly and affected gait -walks with a limp, pain on running and tires easily

• Normal sensation and range of motion• Physical Examination: Swollen firm right thigh with

increased superficial vascularity• No erythema, warmth, bruits or pulsations

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Routine X-ray: large medially placed thigh mass involving soft tissue

Femur with intact cortex and no periosteal reaction

CT and MRI: large heterogenous, hypervascular mass (18 x 13 x 9 cm) with tortuous, enlarged vascular channels(high flow lesion)

Arterial drainage into the right iliac artery and venous drainage into the femoral vein

Radiologists’ Impression

• Mixed Vascular Lesion with Large AVM Component with Intralesional Hemorrhage

• Prior to Embolization of This Possible Hypervascular Lesion with an AVM Component, Biopsy was Performed.

Needle Core Biopsy

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Immunostains• Negative Stains:

– Desmin, Myogenin, MSA, MyoD1

– Chromogranin, S100 Synaptophysin

– CD99– ALK-1– EMA, PanCytokeratin– CD34, CD31, D2-40– MUC4– Collagen Type IV

• Positive Stains:– SMA (focal expression)– INI1 (nuclear)– Beta-Catenin

(cytoplasmic)– Vimentin

INI1

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Cytogenetics & Molecular Genetics

• Karyotype: 46,XY• Negative FISH for EWSR1, SS18, FOXO1

• RT-PCR Translocations Negative for:– Ewing Sarcoma– Synovial Sarcoma– Alveolar Rhabdomyosarcoma– Low-Grade Fibromyxoid Sarcoma

• Distribution of paired-end split and spanning RNA-Seq reads joining BCOR exon 15 with CCNB3 exon 5

• Direct sequencing confirmed RNA-seq reads: BCOR–CCNB3 fusion transcript result of cryptic ‘GT’ splice donor site activation in BCOR exon 15 leading to skipping of ‘TGA’ termination.

• RT-PCR with fusion-specific primers - expression of 171-bp band only in the tumors (current patient T107)

CCNB3 Embolization Prior to Resection

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BCOR-CCNB3 Sarcoma• 1st Described in 2012 by performing RNA-seq on

Translocation Negative Ewing-Like Sarcomas (4% [24/594] undifferentiated sarcoma)

• RNA-Seq identified 20 distinct high-quality paired-end fragments linking Exon 15 of BCOR (Xp11.4) and Exon 5 of CCNB3 (Xp11.22)

• Primers for BCOR Exon 15 and CCNB3 Exon5 designed to perform RT-PCR for BCOR-CCNB3 translocation due to X-chromosome inversion (paracentric)

Summary of BCOR3-CCNB3: Clinicopathologic Correlations (n=26)

• Median age: 13.1 yrs (range 5.9 to 25.6 yrs)• Gender Ratio: 2 Male: 1 Female• Age Groups: 1-9 years 23%

10-17 years 50%>18 years 27%

Clinical Signs at Presentation• Pain 65%• Swelling 40%• Limp 20%• Pathologic Fracture 15%• Fever 10%• Medullary Bone Compression 10%

Summary of BCOR3-CCNB3: Clinicopathologic Correlations

Original Diagnosis• Ewing/PNET 46%• Small Cell Osteosarcoma 11%• Bone Sarcoma, NOS 23%• Soft Tissue Sarcoma, NOS 11%• MPNST 4%• Granulocytic Sarcoma 4%

Immunostain Profile• CCNB3 nuclear 100%• CD99 membranous 16%• CD99 cytoplasmic 24%• CD99 dot-like (Golgi) 48%• Desmin 0%• EMA 0%• Pancytokeratin 0%• S100 protein 0%• SMA 0%• CD34 0%

BCOR-CCNB3 Sarcoma: Differential Diagnosis

• Ewing Sarcoma/PNET with EWSR1-ETS Rearrangement (EWSR1-FLI1; EWSR1-ERG; EWSR1-ETV1; EWSRI-ETV4; EWSR1-FEV)

• Round Cell Sarcoma with EWSR1-nonETS Rearrangement (EWSR1-NFAT2c; EWSR1-SP3; EWSR1-PATZ1; EWSR1-SMARCA5; EWSR1-POU5F1)

• Round Cell Sarcoma with non-EWSR1-ETS Rearrangement (FUS-ERG; FUS-FEV)

• Small Cell Osteosarcoma• Rhabdoid Tumor (INI-1 [SMARCB1] Loss or

SMARCA4 [BRG1] Loss)

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BCOR-CCNB3 Sarcoma: Differential Diagnosis

• Round Cell Sarcoma with CIC-DUX4 Fusion• Undifferentiated Round Cell Tumor• Mesenchymal Chondrosarcoma (HEY1-NCOA2)• Synovial Sarcoma (SS18-SSX1; SS18-SSX4)• Rhabdomyosarcoma (PAX3-FOXO1; PAX7-FOXO1;

11q15)• Desmoplastic Small Round Cell Tumor (EWSR1-

WT1)• Extraskeletal Myxoid Chondrosarcoma (EWSR1-

NR4A3; EWSR1-TAF15; TCF12-NR4A3; TFG-NR4A3)

• Clear Cell Sarcoma of Soft Tissue (EWSR1-ATF1)• Lymphoma/Leukemia/Granulocytic Sarcoma

BCOR Gene• BCOR Mutations: Oculofaciocardiodental

and Lenz micro-ophthalmia syndromes; myeloid leukemia; myelodysplastic syndromes; medulloblastoma

• BCOR-RARA t(X;17): acute promyelocytic leukemia

• BCOR-ZC3H7B t(X;22): Endometrial stromal sarcoma and Ossifying fibromyxoid tumor

• BCOR ins(4;X): Ewing-like undifferentiated round cell sarcoma

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Case History• 8 Yr-Old Hispanic Female with Right Cheek Swelling

Noticed by Parents 1 Month Ago While Visiting Mexico• Went to Dentist in Matamoros: Not A Tooth Problem• PCP in Matamoros: Acyclovir With No Resolution• PCP in Brownsville: – Antibiotics No improvement• Dentist in Brownsville: Problem Due to Chewing on

Teeth. Removed Primary Molars & Incisor –No Change in Swelling

• “Pain Spasms" for 3-4 Hours Night without Relief.• Valley Baptist Hospital: CT with Angle of Jaw Lymph

Node Enlargement – Concern for Malignancy• Transferred To TCH-Houston

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Lymph Node-Hematopathology: S/O ALCL on TPTouch Preparations By Hematopathology

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Permanent Tissue Sections

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Myofilaments

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Desmin Myogenin

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Pax7-FOXO1 RT-PCR:Solid Variant of Alveolar RMS

Pax7-FOXO1Pax3-FOXO1

• 7 Year-Old Male with Recent Onset of Swallowing Problems

• Notice Rapid Increase in Tongue Size a Few Weeks Ago with Increased Drooling

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Desmin Myogenin

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Rhabdomyosarcoma

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Embryonal and Strap Cells

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Spindle Cell, Botryoid & UDS

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Alveolar & Anaplastic

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Genetics: RMS• Alveolar RMS:

– PAX3/FOXO1 (most)– PAX7/FOXO1– PAX3/FOXO4,

PAX3/NCOA1, PAX3/NCOA2FOXO1/FGFR1

– CDK4 Amplification– Mutations: TP53, CDKN2A,

CDKN2B, FGFR4– ALK Copy Gain– Tumor Suppressors: RASSF,

HIC1, CASP8– DNA Methylation

• Embryonal RMS:– 11p15.5: IGF2, H19,

CDKN1C, HOTS– Mutations: RB, TP53,

CDKN2A, CDKN2B, RAS, FGFR4, PIK3CA, CTNNB1 (beta-catenin)

– NF1 Deletions– ALK Copy Gain– DNA Methylation– 12q13: GLI

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Myofilaments

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Paratesticular Tumor in Adolescent:Undifferentiated Pleomorphic Sarcoma

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Small Cell Osteosarcoma

Thigh Mass with Bony Involvement in Adolescent Male

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Sclerosing Rhabdomyosarcoma

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Fibrosarcoma

Lower Extremity Mass in 11 Year-Old Boy

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Embryonal Rhabdomyosarcoma, Spindle Cell

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Histocytosis in Lymph Node (S100, CD1a)

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Rhabdomyoma-Like RhabdomyosarcomaCervical Mass

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Case History• 18 Month Old Male with

Anemia, Fever, Weight Loss, Diarrhea, Hypertension

• Recent Submandibular Lymph Node Enlargement

• Suspected Lymphoblastic Lymphoma/Leukemia

• Underwent Lymph Node Biopsy

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NB84

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Neuroblastoma Family of Tumors

• Three Major Classes of Neuroblastic Tumors Based on Degree of Differentiation of Neuroblastic and Schwannian Stroma Cells– Schwannian Stroma Poor (0 to <50%):

Undifferentiated, Poorly Differentiated and Differentiating Neuroblastomas

– Schwannian Stroma-Rich (>50%): Ganglioneuroblastoma:Intermixed or Nodular Types

– Schwannian Stroma Dominant (nearly 100%): Ganglioneuroma: Maturing and Mature

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• Undifferentiated NB– Small Round Cell

Tumor of Childhood– Lacks Histopathologic

Evidence of Neuroblastic Differentiation

– No Schwannian Stroma Differentiation

– Lack Pseudorosettes– Fine Vascular Capillary

Network

• Undifferentiated NB– High NC Ratio– Lack Neuropil Processes– May Have Fine Granular

Chromatin– May Have Distinct

Nucleoli– Differential Diagnosis

• Rhabdomyosarcoma• Ewing’s Sarcoma• Blastemal Wilms Tumor• Lymphoma/Leukemia• Other SRCT with

Embryonal/Blastemal Appearance

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• Immunophenotype– NB84*– PGP9.5*– NSE– Chromogranin A– Synaptophysin– Tyrosine Hydroxylase*– GD2*– ALK1 in Familial Cases

• Negative for:– VIMENTIN***– Desmin– LMW Keratins– LCA– CD99 Usually Negative,

Rare Positive Cases

NB84

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• Electron Microscopy– Only Necessary with

Undifferentiated Tumors or With Aberrant & Confusing Immunostaining Profile

– Neurite Processes– Dense Core

Neurosecretory Granules– No Other Tumor Defining

Features

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Gene Mutations in Neuroblastoma• Most Hereditary Neuroblastomas (AD

Inheritance) Associated with Activating Mutations in Tyrosine Kinase Domain of Anaplastic Lymphoma Kinase (ALK) Oncogene (Constitutional Mutation)

• ALK Somatic Mutations in 5-15% of Sporadic Neuroblastomas

• PHOX2B: Regulation of ANS Development Participates in Both Hereditary and Sporadic Neuroblastomas– Also Neuroblastomas Associated with

Congenital Central Hypoventilation Syndrome and Hirschsprung’sDisease

• 4 Week-Old Hispanic Male– Red-Brown, Raised

Firm Ulcerated Skin Lesions (multiple)

– Moderate Fever– Recent Onset of

Diarrhea• Differential Diagnosis

– Small Round Cell Tumors

• Leukemia• Neuroblastoma

– Infection

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CD207 (Langerin)

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Langerhans Cell Histiocytosis– Predominantly Disease of Infancy and

Early Childhood (peaks at 3 years of age)– Unifocal; Multifocal & Unisystem; and

Multifocal & Multisystem Disease Patterns– 5 Distinct LCH Clinical Entities

• Eosinophilic Granuloma• Hand-Schuller-Christian Disease• Letterer-Siwe disease• Congenital Self-Healing LCH• Pulmonary LCH

Congenital Self-Healing LCH

• Described 4 Decades Ago– Hashimoto-Pritzker Histiocytosis – Congenital Self-Healing Reticulohistiocytosis

• Represent 10% of Pediatric LCH Cases• Clinical Suspicion for Leukemia, Neuroblastoma,

Small Round Cell Tumors, Infection, JXG & LCH• Indistinguishable from LCH on LM and IHC• Laminated and Non-Laminated Dense Bodies• Pentalaminar Bodies (<30% of LC histiocytes)• Clinical Course: 98% Involute with No Treatment

Deep Subcutaneous Nodule:6 Month Old Hispanic Girl

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Cytogenetics56,X,?r(X)(p22q28),add(1)(p36),+i(1)(q10),+4,+add(6)(q12),+7,add(7)(p11.2)x2,+8,add(12)(q21),+15,+20,+21,+21,+22[16]/46,XX,inv(9)(p11q13)[4]

Flow Cytometry ResultsInterpretation: Not Compatible with Hematopoietic/Lymphoid Neoplasm

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(J Am Acad Dermatol 2002;47:77-90.)

Died of Disease-50%

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• 8 year-old with right shoulder mass and prior history of melanocytic nevus

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DX: Spitz Nevus (epitheliod and spindled nevus)

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3 Years Later: Needle Core Biopsy of Neck Mass

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Example of Various Melanosome Phases 118

S100 ProteinMelan-A

HMB45

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Cytogenetics• 46,XX,add(12)(q24.3),t(?20;22)

(?p11.2;q12) in Only 2 Cells –Probably Balanced Translocation

• Abnormal Chromosomal & FISH (89.5% of Cells) Analysis with EWSR1 Gene Rearrangement

• 21 and 26 Day Primary Cultures

RT-PCR• EWS-ATF1 Performed

on:– Skin Biopsy: Negative– Lung Needle Core and

Biopsy: Positive– Lymph Node Biopsy:

Positive– Proximal Humeral

Resection: Positive

CCSST• <1% of Soft Tissue Tumors (500 cases)• Young to Middle Age Adults & 1.5F:1.0M Ratio• Foot & Ankle Common (33%), Less Often Leg/Knee

(15%), Thigh (12%), Hand (18%), Elbow/Forearm (10%), Trunk (7%), H&N (3%), Genital (2%)

• Deep Seated Tumor Arising From Tendons & Aponeuroses

• Most <5cm• Long Duration Prior to Diagnosis in Most

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CCST• EWS-ATF1 Translocation in >90%• EWS-CREB1 Translocation in Minority

– More Common in GI Clear Cell Sarcoma• ATF1 Member of CREB Family• CREB and ATF1 in Combination with SOX10 –

Crucial in Driving Expression of MITF (regulator of melanocyte differentiation) in normal melanocytes

• Gene Expression Profiles – CCSST Clusters with Melanoma – Expression of Melanocytic Differentiation Genes (MITF, SOX10, ERBB3, FGFR1

2 Month Old Male with Markedly Enlarged Liver & Concern for Neuroblastoma (Stage IVS)

Urinary Catecholamines: NegativeTransferred To Pediatric Hospital

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Congenital Acute Megakaryoblastic Leukemia

• Rare Form of Acute Myeloid Leukemia (1%)• Median Age 4 months (range neonate to 3 yrs)• Mimics Stage IVS Undifferentiated Neuroblastoma

– Hepatomegaly, Anemia, Thrombocytopenia• Liver Biopsy: Displacement of Hepatocytes• Immunoreactivity with

– NB84, NSE, PGP 9.5– CD41, CD61, CD42, CD12, CD33

• Translocation DetectionRMB15-MKL1 (OTT-MAL) – t(1;22)(p13;q13)

6 Year-Old Male with Enlarged Cervical Lymph Nodes

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• Transferred To Pediatric Hospital• Urinary Catecholamines: Positive• Cytogenetics: MYC-N Amplified, Loss of 1p36• Negative for ALCL Translocation

Nature 2008;455:967

Human Pathol 2009;40:1638

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Paraspinal Mass in 7 year-old boy

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Case History• 33 Month-Old Male

with Decreased Heart Tones Shifted to Left & Decreased Breath Sounds on Right

• Moderate Respiratory Distress

• Chest X-Ray with Air-Filled Cysts and Probable Pneumothorax

• CT Scan- Solid Mass• Outside Biopsy:

Rhabdomyosarcoma

Myogenin

Desmin

Solid Tumor Components

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Pleuropulmonary Blastoma (PPB)

• Embryonal Malignant Tumor Derived from Mesenchyme of Lung and Pleura

• Rare Tumor with 20 to 25 Cases Per Year in USA

• First Described in 1988 as Distinct Entity

• Predominantly in Neonates, Infants and Young Children (single documented adult case reported)

• Rarely Reported After 12 years of Age

• Detection May Occur During Routine Prenatal Ultrasound

• Important to Distinguish from Adult Pulmonary Blastoma– Adult Pulmonary

Blastoma: Biphasic Tumor with Both Malignant Mesenchymal and Epithelial (glandular) Components

– PPB: Only Malignant Mesenchymal Component and No Malignant Epithelial Component

• Equal Gender Ratio• Laterality: Right Lung 54%;

Left Lung 37%; Bilateral 9%)

• Brain 15-25%– Type III PPBs 54%– Type II PPBs 11%

• Bone 6-10%• Liver 2-4%

• Contralateral Lung• Ovary• Spinal Cord & Leptomeninges• Adrenal Glands• Pancreas• Choroid of Eye & Iris• Time to Metastases: 24 Months from

Diagnosis in Most

PPB & Metastatic Disease

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PPB Family Tumors and Dysplasia Syndrome• Familial Distribution in 33%• Usually Occurs in First Two Decades of

Life• Associated with Dicer 1 Mutation• Tumors/Dysplasias

– Lung Cysts (Dicer 1 Mutation)– Cystic Nephroma (9-10%, Dicer 1

Mutation)– Wilms Tumor (Dicer 1 Mutation)– Dysplasias

• Intestinal Hamartomatous Polyps (Ileal most common with Intussusception)

• Cystic Hepatic Hamartoma– Nasal Chondromesenchymal

Hamartoma (Dicer 1 Mutation)– Ciliary Body Medulloepithelioma

(Dicer 1 Mutation)– Ovarian Fibroma (Dicer 1 Mutation)– Rhabdomyosarcoma (Dicer 1

Mutation)

• Neuroblastoma, Medulloblastoma, & Other CNS Tumors

• Leukemias• Gonadal Tumors

– Sertoli-Leydig Cell Tumors (Dicer 1 Mutation)

– Dysgerminoma (Dicer 1 Mutation)

– Seminoma (Dicer 1 Mutation)– Germ Cell Tumors

• Uterine/Cervival Sarcoma Botryoides(Dicer 1 Mutation)

– Adolescent and Young Women• Thyroid

– Nodular Thyroid Hyperplasia (Dicer 1 Mutation)

– Follicular and Papillary Thyroid Carcinomas (Dicer 1 Mutation)

• Renal Sarcoma• Other Sarcomas

PPB: SurvivalFive-Year Overall Survival Rates:

– Type I PPBs: 85%– Type II PPBs: 58% – Type III PPBs: 42%

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PPB Stands Out Among Other Lung Cysts

Case History:• 12 year-old female with

slowly enlarging tongue mass• Recently mass has increased

rapidly in size• Hypervascular mass with

prominent draining veins on angiography & CT

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Translocation:der(17)(X;17)(p11;q25)ASPL-TFE3 Fusion

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Alveolar Soft Part Sarcoma• Most Common Between Ages 5-35 yrs• Gender Ratio 2F:1M in <30 Yr Age• Reversed Gender Ratio in >30 Yr Age• Represents 0.2-0.9% of Soft Tissue Sarcomas• Rare Before Age 5 Yrs• Most Common Sites:

– Children: Head and Neck – Tongue and Orbit– Adults: Deep Soft Tissues of Thigh or Buttocks

• Slow Growing Painless Tumors• Mets to Brain or Lung – 1st Presentation

Alveolar Soft Part Sarcoma

• TFE Carboxy Terminal Immunoreactive: Nuclear Pattern– Granular Cell Tumors

• S100, Desmin (50%)• Translocation:

– der(17)(X;17)(p11;q25)– ASPL-TFE3 Fusion– RT-PCR or FISH– Transcription Factor:

Activates MET Signaling– MET Inhibitors Target

Alveolar Soft Part Sarcoma

• Prognosis• Seldom Recur Locally After Excision• Metastases Common with Long-Term

Followup• Survival with No Metastases at Diagnosis:

– 5 Yrs 60%, 10Yrs 38%, 20 Yrs 15%• Prognostic Factors: Age, Size and Mets• Metastatic Sites: Lung, Bone & Brain

Before ASPS Signout, Be Aware• Renal Cell Carcinomas Account for <5% of

All Pediatric Renal Tumors• Xp11.2 Translocation Renal Cell Carcinomas

– Account for Up to 75% of Renal Cell Carcinomas in Pediatrics

– Tendency to Present at Advanced Stages– Metastases Common Despite Often Small Size of Tumor– Clinical Course Variably with Indolent Course in Most

Patients, but Rapidly Fatal In Others

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Xp11.2 Renal Cell CarcinomaTFE3 Located at Xp11.2 Has Several FusionPartners That Lead To Renal Cell Carcinoma• ASPL-TFE3 t(X;17)(p11.2;q25) 2 to 68 Yrs

• PRCC-TFE3 t(X;1)(p11.2;q21) 2 to 70 Yrs

• PSF-TFE3 t(X;1)(p11.2;p34) 3 to 68 Yrs

• NonO-TFE3 inv(X)(p11.2;q12) 39 Yrs(Rare)

• CLTC-TFE3 t(X;17)(p11.2;q23) 14 Yrs(Rare)

ASPL-TFE3 t(X;17)(p11.2;q25)

TFE3

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DICER1• Cytoplasmic

Endoribonuclease (DOSHA) Cleaves Precursors into miRNA and siRNA.

• Small Silencing siRNAs Critical in Controlling Messenger RNA (mRNA).

• Participates in RNA-Induced Silencing Complex (RISC), which Degrades or Suppresses mRNA

Novel Cancer Induction Mechanism• Pulmonary Epithelial Cells Benign

– Segmental/Focal DICER1 Loss• DICER1 in Malignant Mesenchymal

Cells • Dysregulated Autocrine Signaling

From Epithelial to Mesenchymal Cells– Signaling Important for

Branching & Morphogenesis in Normal Developing Lung

– Dysregulation Induces Cyst Formation and Malignancy in Mesenchymal Cells