Role of cytogenetics in diagnosis of pediatric solid tumors md patholo

Role of cytogenetics in diagnosis of pediatric solid tumors md pathology exam robbins based answer

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pediatric solid tumors AND molecular diagnosis

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Role of cytogenetics in diagnosis of pediatric solid tumors

Introduction

Pediatric solid tumors are often embryonal tumors with primitive morphology, many appearing as small round blue cell tumors. Because morphology and immunohistochemistry may overlap, cytogenetic and molecular genetic tests are important adjuncts for confirming diagnosis, classifying the tumor, estimating prognosis, detecting hereditary predisposition, and selecting targeted treatment.

Robbins notes that although many childhood tumors can be identified histologically, confirmatory molecular studies are routinely used both for diagnosis and prognostic assessment. Robbins & Kumar Basic Pathology, p. 145.

Methods used

Method	Main utility
Conventional karyotyping	Detects numerical and structural chromosome abnormalities, balanced translocations, double minutes, and homogeneously staining regions. Requires viable dividing cells.
FISH	Rapid, tissue-based detection of gene amplification, deletions, and gene rearrangements. Useful on paraffin sections.
RT-PCR / fusion transcript assay	Detects specific fusion transcripts with high sensitivity.
Chromosomal microarray / SNP array	Detects copy-number changes and loss of heterozygosity (LOH).
NGS-based fusion panels and sequencing	Identifies cryptic rearrangements, mutations, and therapeutic targets.
Germline testing	Identifies inherited cancer-predisposition syndromes and guides family counseling.

Diagnostic roles

1. Establishes or confirms the tumor type

Many pediatric sarcomas harbor characteristic, often reciprocal, chromosomal translocations producing oncogenic fusion genes. Demonstration of these rearrangements is particularly helpful when histology is equivocal.

Tumor	Characteristic cytogenetic / molecular abnormality	Diagnostic significance
Ewing sarcoma	t(11;22)(q24;q12), forming EWSR1::FLI1 fusion in most tumors	Supports diagnosis of Ewing sarcoma among small round blue cell tumors.
Alveolar rhabdomyosarcoma	t(2;13)(q35;q14), PAX3::FOXO1; or t(1;13)(p36;q14), PAX7::FOXO1	Identifies fusion-positive alveolar RMS and separates it from embryonal RMS.
Synovial sarcoma	t(X;18)(p11;q11), SS18::SSX fusion	Confirms synovial sarcoma in a monophasic spindle-cell or poorly differentiated tumor.
Desmoplastic small round cell tumor	t(11;22)(p13;q12), EWSR1::WT1 fusion	Characteristic for DSRCT.
Infantile fibrosarcoma / congenital mesoblastic nephroma	t(12;15)(p13;q25), ETV6::NTRK3 fusion	Confirms diagnosis and identifies a targetable NTRK fusion.
Clear cell sarcoma of soft tissue	EWSR1::ATF1 or EWSR1::CREB1	Helps distinguish it from melanoma and other clear-cell tumors.

Important caution: an EWSR1 break-apart FISH positivity is not specific for Ewing sarcoma, since EWSR1 rearrangement also occurs in several other tumors. A fusion-specific test and morphologic correlation are required.

In Ewing sarcoma, Robbins describes a balanced translocation involving EWSR1 on chromosome 22 and FLI1 on chromosome 11, producing a chimeric transcription factor that disrupts normal transcriptional regulation. Robbins & Kumar Basic Pathology, p. 786.

2. Resolves the differential diagnosis of small round blue cell tumors

Neuroblastoma, Ewing sarcoma, rhabdomyosarcoma, lymphoma, retinoblastoma, and some Wilms tumors can share a small round blue cell appearance. Cytogenetics can distinguish these morphologically similar tumors.

Examples:

EWSR1::FLI1 favors Ewing sarcoma.
PAX3/7::FOXO1 favors alveolar rhabdomyosarcoma.
MYCN amplification supports high-risk neuroblastoma.
RB1 deletion/mutation supports retinoblastoma.
WT1 abnormalities or 11p alterations support Wilms tumor in the relevant clinical and morphologic setting.

Prognostic roles

3. Risk stratification in neuroblastoma

Cytogenetic analysis is central to neuroblastoma risk grouping.

Abnormality	Significance
MYCN amplification	Strong adverse prognostic marker, associated with aggressive disease and high-risk neuroblastoma. Detected by FISH or molecular methods.
1p deletion	Associated with unfavorable outcome.
11q deletion	Adverse marker, often seen in tumors without MYCN amplification.
17q gain	Associated with aggressive behavior.
Near-triploidy / hyperdiploidy in young children	Generally associated with a better outcome than segmental chromosomal aberrations.

FISH can demonstrate MYCN amplification as multiple amplified signals, sometimes corresponding cytogenetically to double-minute chromosomes or homogeneously staining regions. Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 307.

4. Risk assessment in Wilms tumor

Wilms tumor is associated with abnormalities of tumor-suppressor genes and chromosomal regions.

WT1 mutation or deletion at 11p13
- Associated with WAGR syndrome and Denys-Drash syndrome.
11p15 abnormalities
- Linked to Beckwith-Wiedemann syndrome and altered imprinting/growth signaling.
Loss of heterozygosity at 1p and 16q
- Associated with increased risk of relapse and adverse outcome.
- Their combined presence has been used for intensified treatment in risk-adapted protocols.

Thus, cytogenetics helps identify children who may require more intensive therapy and also identifies patients with syndromic predisposition. Robbins & Kumar Basic Pathology, pp. 148-149.

5. Prognostic subclassification of rhabdomyosarcoma

Fusion-positive alveolar RMS with PAX3::FOXO1 or PAX7::FOXO1 has a less favorable prognosis than fusion-negative RMS.
Cytogenetics therefore has greater prognostic value than morphology alone in some tumors originally classified as alveolar RMS.
Embryonal RMS usually lacks these recurrent PAX-FOXO1 rearrangements.

Detection of hereditary cancer predisposition

6. Identifies germline mutations and permits family counseling

Cytogenetic and molecular testing can identify a constitutional abnormality underlying a pediatric tumor.

Tumor	Hereditary genetic association	Clinical value
Retinoblastoma	Germline RB1 mutation at 13q14	Predicts bilateral/multifocal disease, risk to siblings and offspring, and increased risk of later osteosarcoma and soft-tissue sarcoma.
Wilms tumor	WT1-related syndromes, WAGR, Denys-Drash, Beckwith-Wiedemann syndrome	Enables surveillance of the contralateral kidney and screening for associated anomalies.
Neuroblastoma	Germline ALK or PHOX2B mutations in familial cases	Enables family testing and surveillance.
Rhabdomyosarcoma	TP53 mutation in Li-Fraumeni syndrome, DICER1-related predisposition in selected subtypes	Guides genetic counseling and surveillance.

In retinoblastoma, approximately 40% of cases are associated with a germline RB1 mutation; a second somatic hit in retinal progenitor cells causes tumor formation. Germline disease commonly produces bilateral tumors. Robbins & Kumar Basic Pathology, p. 122.

Predictive and therapeutic roles

7. Identifies actionable molecular targets

Cytogenetics has moved beyond diagnosis and prognosis to treatment selection.

ETV6::NTRK3 fusion in infantile fibrosarcoma or congenital mesoblastic nephroma predicts potential response to TRK inhibitors.
ALK alterations in neuroblastoma may allow ALK-targeted therapy in appropriate high-risk or relapsed disease.
Specific kinase fusions may support enrollment in molecularly matched clinical trials.

This reflects the current WHO approach, which integrates histopathology with molecular pathology in classification of pediatric tumors, as outlined by the WHO pediatric tumor classification.

Limitations

A cytogenetic abnormality should not be interpreted in isolation. Correlation with age, site, morphology, immunohistochemistry, and radiology is necessary.
Conventional karyotyping may fail if fresh viable tumor cells are unavailable or tumor cells do not divide in culture.
FISH identifies a targeted abnormality but may not determine the fusion partner.
A negative result does not exclude a tumor when the test is technically limited or when an alternate fusion is present.
Broad molecular tests may reveal variants of uncertain significance, particularly in germline testing.

Conclusion

Cytogenetics is an essential component of the diagnosis of pediatric solid tumors. Its major roles are:

Confirming diagnosis by demonstrating tumor-specific translocations or gene fusions.
Differentiating small round blue cell tumors with overlapping morphology.
Providing prognostic information, especially MYCN amplification in neuroblastoma and 1p/16q LOH in Wilms tumor.
Detecting inherited cancer predisposition, notably RB1 and WT1-related disorders.
Guiding precision therapy by identifying actionable fusions or mutations.

Exam one-liner:
Cytogenetics in pediatric solid tumors provides diagnostic confirmation through characteristic chromosomal rearrangements, assists in differential diagnosis of small round blue cell tumors, stratifies prognosis, detects hereditary predisposition, and identifies targets for personalized therapy.

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Robbins pathology pediatric solid tumors cytogenetics EWSR1 FLI1 MYCN Wilms tumor LOH 1p 16q

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Running Command

mkdir -p "/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf" cat > "/tmp/workspace/pediatric-solid-tumor-cytogenetics/make_revision_pdf.py" <<'PY' from reportlab.lib.pagesizes import A4 from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle, KeepTogether from reportlab.lib import colors from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle from reportlab.lib.enums import TA_CENTER from reportlab.lib.units import cm from reportlab.pdfbase.pdfmetrics import stringWidth out='/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf/Cytogenetics_Pediatric_Solid_Tumors_Revision.pdf' doc=SimpleDocTemplate(out,pagesize=A4,rightMargin=1.0*cm,leftMargin=1.0*cm,topMargin=0.85*cm,bottomMargin=0.8*cm) styles=getSampleStyleSheet() styles.add(ParagraphStyle(name='TitleX',parent=styles['Title'],fontName='Helvetica-Bold',fontSize=15,leading=17,alignment=TA_CENTER,textColor=colors.HexColor('#12345A'),spaceAfter=4)) styles.add(ParagraphStyle(name='Sub',parent=styles['Normal'],fontName='Helvetica',fontSize=7.6,leading=9,alignment=TA_CENTER,textColor=colors.HexColor('#555555'),spaceAfter=6)) styles.add(ParagraphStyle(name='H',parent=styles['Heading2'],fontName='Helvetica-Bold',fontSize=9.2,leading=11,textColor=colors.white,backColor=colors.HexColor('#1D5D87'),spaceBefore=4,spaceAfter=3,leftIndent=3)) styles.add(ParagraphStyle(name='B',parent=styles['BodyText'],fontName='Helvetica',fontSize=7.15,leading=8.55,spaceAfter=2)) styles.add(ParagraphStyle(name='Small',parent=styles['BodyText'],fontName='Helvetica',fontSize=6.55,leading=7.5,spaceAfter=1.2)) styles.add(ParagraphStyle(name='Tiny',parent=styles['BodyText'],fontName='Helvetica',fontSize=5.9,leading=6.7,textColor=colors.HexColor('#404040'))) def p(txt, sty='B'): return Paragraph(txt, styles[sty]) def table(data,widths,fontsize=6.3): t=Table([[p(x,'Small') if not isinstance(x,Paragraph) else x for x in row] for row in data],colWidths=widths,repeatRows=1) t.setStyle(TableStyle([ ('BACKGROUND',(0,0),(-1,0),colors.HexColor('#D9EAF7')),('TEXTCOLOR',(0,0),(-1,0),colors.HexColor('#12345A')), ('FONTNAME',(0,0),(-1,0),'Helvetica-Bold'),('VALIGN',(0,0),(-1,-1),'TOP'), ('GRID',(0,0),(-1,-1),0.25,colors.HexColor('#AAC4D6')),('LEFTPADDING',(0,0),(-1,-1),3),('RIGHTPADDING',(0,0),(-1,-1),3), ('TOPPADDING',(0,0),(-1,-1),2),('BOTTOMPADDING',(0,0),(-1,-1),2), ('ROWBACKGROUNDS',(0,1),(-1,-1),[colors.white,colors.HexColor('#F6FAFD')])])) return t story=[] story += [p('CYTOGENETICS IN PEDIATRIC SOLID TUMORS','TitleX'),p('One-page MD Pathology revision | Robbins-based high-yield answer','Sub')] story += [p('CORE IDEA','H'),p('Why needed? Pediatric tumors commonly show primitive or “small round blue cell” morphology. Cytogenetics and molecular tests confirm lineage-defining alterations, resolve mimics, provide risk stratification, reveal germline predisposition, and sometimes identify drug targets. Histology + IHC remain essential: genetics is interpreted in clinicopathologic context.')] story += [p('TESTS: MATCH THE METHOD TO THE QUESTION','H'),table([ ['Test','Best use / limitation'], ['Karyotype','Numerical/structural alterations, double minutes, homogeneously staining regions; needs viable dividing tumor cells.'], ['FISH','Rapid on tissue sections: amplification, deletion, rearrangement. Break-apart FISH proves rearrangement but may not identify the partner.'], ['RT-PCR / RNA fusion NGS','Confirms specific fusion transcript; detects cryptic and alternative fusions.'], ['Array / SNP array','Copy-number change and loss of heterozygosity (LOH).'], ['Germline testing','Predisposition syndromes, family counseling, surveillance.'] ],[3.55*cm,15.45*cm])] story += [p('DIAGNOSTIC FUSIONS: EXAM TABLE','H'),table([ ['Tumor','Key abnormality','Role in diagnosis'], ['Ewing sarcoma','t(11;22)(q24;q12) EWSR1::FLI1 (most); other EWSR1-ETS fusions','Confirms Ewing among small round blue cell tumors. EWSR1 break-apart alone is not specific.'], ['Alveolar RMS','t(2;13) PAX3::FOXO1; t(1;13) PAX7::FOXO1','Defines fusion-positive ARMS; separates from embryonal RMS and also carries prognostic value.'], ['Synovial sarcoma','t(X;18) SS18::SSX','Confirms diagnosis, including monophasic spindle-cell tumors.'], ['DSRCT','t(11;22) EWSR1::WT1','Highly characteristic confirmation.'], ['Infantile fibrosarcoma / congenital mesoblastic nephroma','t(12;15) ETV6::NTRK3','Diagnostic and predictive: NTRK-directed therapy may be relevant.'] ],[3.35*cm,6.05*cm,9.6*cm])] story += [p('RISK, PROGNOSIS AND PREDISPOSITION','H'),table([ ['Tumor','Cytogenetic finding','Clinical implication'], ['Neuroblastoma','MYCN amplification; 1p loss, 11q loss, 17q gain','MYCN amplification is a major adverse marker. FISH detects amplified MYCN; cytogenetic correlates include double minutes/HSRs. Used for risk grouping.'], ['Wilms tumor','LOH 1p + 16q; WT1 at 11p13; 11p15 imprinting defects','Combined 1p/16q LOH signals relapse risk. WT1/11p abnormalities point to syndromic predisposition.'], ['Retinoblastoma','RB1 inactivation at 13q14','Germline mutation: bilateral/multifocal disease, familial risk, and risk of second cancers. Tumor follows the two-hit model.'], ['Rhabdomyosarcoma','FOXO1 fusion-positive ARMS','Generally worse-risk biology than fusion-negative RMS; molecular subtype is more useful than morphology alone.'] ],[3.35*cm,6.0*cm,9.65*cm])] story += [p('HOW TO WRITE THE 5-MARK ANSWER','H'),p('1. Define cytogenetics as detection of chromosome number/structure, gene amplification, deletion and fusion. 2. State diagnostic role in small round blue cell tumors with EWSR1::FLI1 and PAX3/7::FOXO1 examples. 3. Add prognosis: MYCN amplification in neuroblastoma; LOH 1p/16q in Wilms tumor. 4. Add germline role: RB1 and WT1 syndromes. 5. Conclude with targeted therapy example: ETV6::NTRK3.')] story += [Spacer(1,3),p('One-line conclusion: Cytogenetics converts morphology into a biologically defined diagnosis, refines prognosis, detects heritable cancer risk, and can direct precision therapy.','B')] story += [Spacer(1,3),p('Robbins anchors: Pediatric tumors and confirmatory molecular studies: Robbins & Kumar Basic Pathology, p. 145. Ewing sarcoma: p. 786. Retinoblastoma/RB1: p. 122. Neuroblastoma MYCN FISH: Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 307.','Tiny')] def footer(canvas, doc): canvas.saveState(); canvas.setFont('Helvetica',6.2); canvas.setFillColor(colors.HexColor('#666666')) canvas.drawCentredString(A4[0]/2,0.43*cm,'MD Pathology revision sheet | Cytogenetics in pediatric solid tumors') canvas.restoreState() doc.build(story,onFirstPage=footer) print(out) PY python "/tmp/workspace/pediatric-solid-tumor-cytogenetics/make_revision_pdf.py" && python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf/Cytogenetics_Pediatric_Solid_Tumors_Revision.pdf' r=PdfReader(p) print('pages=',len(r.pages),'bytes=',__import__('os').path.getsize(p)) print((r.pages[0].extract_text() or '')[:350]) PY

Running Command

mkdir -p "/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf" && printf '%s\n' 'directory created'

Writing File

~/pediatric-solid-tumor-cytogenetics/make_revision_pdf.py

from reportlab.lib.pagesizes import A4
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle
from reportlab.lib import colors
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.enums import TA_CENTER
from reportlab.lib.units import cm

out = '/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf/Cytogenetics_Pediatric_Solid_Tumors_Revision.pdf'
doc = SimpleDocTemplate(out, pagesize=A4, rightMargin=1.0*cm, leftMargin=1.0*cm, topMargin=0.8*cm, bottomMargin=0.8*cm)
styles = getSampleStyleSheet()
styles.add(ParagraphStyle(name='TitleX', parent=styles['Title'], fontName='Helvetica-Bold', fontSize=15, leading=17, alignment=TA_CENTER, textColor=colors.HexColor('#12345A'), spaceAfter=4))
styles.add(ParagraphStyle(name='Sub', parent=styles['Normal'], fontName='Helvetica', fontSize=7.6, leading=9, alignment=TA_CENTER, textColor=colors.HexColor('#555555'), spaceAfter=6))
styles.add(ParagraphStyle(name='H', parent=styles['Heading2'], fontName='Helvetica-Bold', fontSize=9.2, leading=11, textColor=colors.white, backColor=colors.HexColor('#1D5D87'), spaceBefore=4, spaceAfter=3, leftIndent=3))
styles.add(ParagraphStyle(name='B', parent=styles['BodyText'], fontName='Helvetica', fontSize=7.15, leading=8.55, spaceAfter=2))
styles.add(ParagraphStyle(name='Small', parent=styles['BodyText'], fontName='Helvetica', fontSize=6.55, leading=7.5, spaceAfter=1.2))
styles.add(ParagraphStyle(name='Tiny', parent=styles['BodyText'], fontName='Helvetica', fontSize=5.9, leading=6.7, textColor=colors.HexColor('#404040')))

def p(txt, sty='B'):
    return Paragraph(txt, styles[sty])

def table(data, widths):
    rows = [[p(x, 'Small') if not isinstance(x, Paragraph) else x for x in row] for row in data]
    t = Table(rows, colWidths=widths, repeatRows=1)
    t.setStyle(TableStyle([
        ('BACKGROUND', (0,0), (-1,0), colors.HexColor('#D9EAF7')),
        ('TEXTCOLOR', (0,0), (-1,0), colors.HexColor('#12345A')),
        ('FONTNAME', (0,0), (-1,0), 'Helvetica-Bold'),
        ('VALIGN', (0,0), (-1,-1), 'TOP'),
        ('GRID', (0,0), (-1,-1), 0.25, colors.HexColor('#AAC4D6')),
        ('LEFTPADDING', (0,0), (-1,-1), 3), ('RIGHTPADDING', (0,0), (-1,-1), 3),
        ('TOPPADDING', (0,0), (-1,-1), 2), ('BOTTOMPADDING', (0,0), (-1,-1), 2),
        ('ROWBACKGROUNDS', (0,1), (-1,-1), [colors.white, colors.HexColor('#F6FAFD')])
    ]))
    return t

story = [
    p('CYTOGENETICS IN PEDIATRIC SOLID TUMORS', 'TitleX'),
    p('One-page MD Pathology revision | Robbins-based high-yield answer', 'Sub'),
    p('CORE IDEA', 'H'),
    p('<b>Why needed?</b> Pediatric tumors often have primitive or “small round blue cell” morphology. Cytogenetics and molecular tests confirm defining alterations, resolve mimics, stratify risk, reveal germline predisposition, and can identify drug targets. Interpret results with morphology, IHC, site, age, and imaging.'),
    p('TESTS: MATCH THE METHOD TO THE QUESTION', 'H'),
    table([
        ['Test', 'Best use / limitation'],
        ['Karyotype', 'Numerical/structural abnormalities, double minutes, homogeneously staining regions; requires viable dividing tumor cells.'],
        ['FISH', 'Rapid on tissue: amplification, deletion, or rearrangement. Break-apart FISH proves rearrangement but may not identify fusion partner.'],
        ['RT-PCR / RNA fusion NGS', 'Confirms specific fusion; detects cryptic and alternative fusions.'],
        ['Array / SNP array', 'Copy-number changes and loss of heterozygosity (LOH).'],
        ['Germline testing', 'Predisposition syndromes, family counseling, surveillance.']
    ], [3.55*cm, 15.45*cm]),
    p('DIAGNOSTIC FUSIONS: EXAM TABLE', 'H'),
    table([
        ['Tumor', 'Key abnormality', 'Diagnostic role'],
        ['Ewing sarcoma', 't(11;22)(q24;q12) <b>EWSR1::FLI1</b> (most); other EWSR1-ETS fusions', 'Confirms Ewing among small round blue cell tumors. <b>EWSR1 break-apart alone is not specific.</b>'],
        ['Alveolar RMS', 't(2;13) <b>PAX3::FOXO1</b>; t(1;13) <b>PAX7::FOXO1</b>', 'Defines fusion-positive ARMS; separates it from embryonal RMS and has prognostic value.'],
        ['Synovial sarcoma', 't(X;18) <b>SS18::SSX</b>', 'Confirms diagnosis, including monophasic spindle-cell tumors.'],
        ['DSRCT', 't(11;22) <b>EWSR1::WT1</b>', 'Highly characteristic confirmation.'],
        ['Infantile fibrosarcoma / congenital mesoblastic nephroma', 't(12;15) <b>ETV6::NTRK3</b>', 'Diagnostic and predictive: NTRK-directed therapy may be relevant.']
    ], [3.35*cm, 6.05*cm, 9.6*cm]),
    p('RISK, PROGNOSIS AND PREDISPOSITION', 'H'),
    table([
        ['Tumor', 'Cytogenetic finding', 'Clinical implication'],
        ['Neuroblastoma', '<b>MYCN amplification</b>; 1p loss, 11q loss, 17q gain', 'MYCN amplification is a major adverse marker. FISH detects amplification; double minutes/HSRs are cytogenetic correlates. Used for risk grouping.'],
        ['Wilms tumor', '<b>LOH 1p + 16q</b>; WT1 at 11p13; 11p15 imprinting defects', 'Combined 1p/16q LOH signals increased relapse risk. WT1/11p abnormalities suggest syndromic predisposition.'],
        ['Retinoblastoma', '<b>RB1</b> inactivation at 13q14', 'Germline mutation: bilateral/multifocal disease, familial risk, and later second cancers. Two-hit model.'],
        ['Rhabdomyosarcoma', 'FOXO1 fusion-positive ARMS', 'Generally worse-risk biology than fusion-negative RMS; molecular subtype is more useful than morphology alone.']
    ], [3.35*cm, 6.0*cm, 9.65*cm]),
    p('HOW TO WRITE THE 5-MARK ANSWER', 'H'),
    p('<b>1.</b> Define: detection of chromosome number/structure, amplification, deletion and fusion.  <b>2.</b> Diagnostic role in small round blue cell tumors: EWSR1::FLI1 and PAX3/7::FOXO1.  <b>3.</b> Prognosis: MYCN amplification in neuroblastoma; LOH 1p/16q in Wilms tumor.  <b>4.</b> Germline role: RB1 and WT1 syndromes.  <b>5.</b> Targeted therapy: ETV6::NTRK3.'),
    Spacer(1, 3),
    p('<b>One-line conclusion:</b> Cytogenetics converts morphology into a biologically defined diagnosis, refines prognosis, detects heritable cancer risk, and can direct precision therapy.'),
    Spacer(1, 3),
    p('<b>Robbins anchors:</b> Pediatric tumors and confirmatory molecular studies: <i>Robbins & Kumar Basic Pathology</i>, p. 145. Ewing sarcoma: p. 786. Retinoblastoma/RB1: p. 122. Neuroblastoma MYCN FISH: <i>Robbins, Cotran & Kumar Pathologic Basis of Disease</i>, p. 307.', 'Tiny')
]

def footer(canvas, doc):
    canvas.saveState()
    canvas.setFont('Helvetica', 6.2)
    canvas.setFillColor(colors.HexColor('#666666'))
    canvas.drawCentredString(A4[0]/2, 0.43*cm, 'MD Pathology revision sheet | Cytogenetics in pediatric solid tumors')
    canvas.restoreState()

doc.build(story, onFirstPage=footer)
print(out)

Running Command

python "/tmp/workspace/pediatric-solid-tumor-cytogenetics/make_revision_pdf.py" && python - <<'PY' from pypdf import PdfReader from pathlib import Path p=Path('/tmp/workspace/pediatric-solid-tumor-cytogenetics/pdf/Cytogenetics_Pediatric_Solid_Tumors_Revision.pdf') r=PdfReader(str(p)) text='\n'.join(page.extract_text() or '' for page in r.pages) print('exists=',p.exists(),'pages=',len(r.pages),'bytes=',p.stat().st_size) print('text_chars=',len(text)) print(text[:500]) PY

Created a verified single-page PDF revision sheet.

Cytogenetics Pediatric Solid Tumors Revision

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