πŸ“‹ MOCK OSCE Β· FCPS, MCPS, MD PAEDIATRICS ⏱ 10 min Β· ABDOMINAL MASS (WILMS TUMOR)

Wilms Tumor Β· Short Case

Candidate task: perform focused clinical examination (GPE + abdomen) on a child with suspected Wilms tumor.
Then discuss differential diagnosis, investigations, management & follow‑up.
Pre‑exam Protocol
⏀ Β· Wash, Warm, Introduce, Position, Expose, Approach β–Ύ

Standard pre‑examination protocol – must be demonstrated:

πŸ– Wash hands with sterilizing solution.
πŸ”₯ Warm hands and stethoscope.
πŸ‘‹ Introduce yourself to child & parent.
🧍 Position child: standing β†’ sitting β†’ supine.
πŸ‘• Exposure β€” shirt off, trousers rolled.
➑️ Approach from the right side.
βœ” CPSP marker: Pre‑exam Protocol is observed and scored.
1. Clinical Examination (β‰ˆ6 min)
02 General Look (Inspection from end of bed) β–Ύ

Key observations:

  • Abdomen: asymmetrical bulging (flank mass), abdominal distension.
  • Nutritional status: wasting (if advanced disease).
  • Dysmorphic features: hemihypertrophy, aniridia (WAGR syndrome), Beckwith-Wiedemann (macroglossia, omphalocele).
  • Skin: pallor (anaemia), bruising (coagulopathy).
  • Mental state: alert; hypertension may cause irritability.
πŸ‘ Red flags: unilateral flank mass + hemihypertrophy + aniridia β†’ Wilms tumor.
03 General Physical Exam (Hands β†’ Face β†’ Chest β†’ Limbs) β–Ύ

Systematic examination:

  • Hands: clubbing (rare), pallor (anaemia).
  • Face: aniridia (WAGR), hemihypertrophy, macroglossia (Beckwith-Wiedemann).
  • Chest: signs of pulmonary metastases (dullness, decreased breath sounds).
  • Abdomen: see next step.
  • Lower limbs: ankle oedema (if renal failure), hypertension (blood pressure measurement).
πŸ“ Anthropometry: weight, height, BMI – plot growth.
04 Abdominal Examination β–Ύ

Systematic approach:

  • Inspection: asymmetrical distension, visible mass, dilated veins (if IVC obstruction).
  • Auscultation: bowel sounds (normal/obstructive), bruits (vascular – rare).
  • Palpation: firm, smooth, non-tender flank mass; does NOT cross midline (unlike neuroblastoma). Assess mobility (renal mass moves with respiration).
  • Percussion: dull over mass; normal resonance over bowel.
  • Rectal: if indicated – pelvic extension.
πŸ” Key: unilateral flank mass + firm + smooth + does not cross midline β†’ Wilms tumor.
05 Developmental Assessment & Associated Signs β–Ύ

Assess:

  • Neurological: developmental delay (if syndromic – WAGR, Beckwith-Wiedemann).
  • Eyes: aniridia (WAGR syndrome), cataracts (if radiation).
  • Genitourinary: ambiguous genitalia (Denys-Drash), cryptorchidism.
  • Growth: overgrowth (Beckwith-Wiedemann), short stature (if chronic disease).
🧠 Syndromic clues: aniridia + GU anomalies + MR β†’ WAGR; hemihypertrophy + macroglossia β†’ Beckwith-Wiedemann.

πŸ“‹ Case Presentation – (fill in during exam)

This is a _____-year-old _____ child, brought with _____ (abdominal swelling / abdominal pain / haematuria). On examination, the child appears _____ (well/unwell), with _____ (pallor / hypertension / aniridia). There is a _____ (firm / smooth / non-tender) mass in the _____ (right/left) flank, measuring approximately _____ cm. The mass _____ (does / does not) cross the midline, and _____ (moves / does not move) with respiration. Growth parameters: weight _____ percentile, height _____ percentile. Additional findings: _____ (haematuria / hypertension / syndromic features).

2. Viva Discussion (β‰ˆ4 min)
06 Viva Β· Differential, Investigations, Management, Follow‑up β–Ύ
πŸ”Ή Differential Diagnosis

β€’ Wilms tumor (nephroblastoma) – most common renal malignancy
β€’ Neuroblastoma – adrenal, crosses midline, calcifications, catecholamines
β€’ Mesoblastic nephroma – neonatal, benign
β€’ Clear cell sarcoma of kidney – aggressive, bone metastases
β€’ Rhabdoid tumor of kidney – aggressive, young infants
β€’ Renal cell carcinoma – rare in children, older adolescents
β€’ Hydronephrosis – cystic, fluctuant, may be bilateral
β€’ Polycystic kidney disease – bilateral, family history
β€’ Non-Hodgkin lymphoma – bilateral, rapid, B symptoms
β€’ Hepatoblastoma – right upper quadrant, AFP elevated
β€’ Gonadal germ cell tumor – pelvic, Ξ²-hCG/AFP
β€’ Ovarian teratoma – female, pelvic/abdominal mass

πŸ”Ή Investigations – Diagnosis

β€’ Abdominal ultrasound – first-line; shows intrarenal mass, IVC thrombus
β€’ CT abdomen & pelvis – with contrast; defines extent, contralateral kidney
β€’ Chest CT – lung metastases (most common site)
β€’ MRI abdomen – if IVC thrombus suspected, or pregnancy
β€’ Urinalysis – haematuria (18% cases), proteinuria
β€’ CBC – anaemia, thrombocytosis, polycythaemia
β€’ LFTs, renal function – baseline for chemotherapy
β€’ Coagulation profile – acquired von Willebrand disease

πŸ”Ή Investigations – Aetiology

β€’ WT1 gene – 11p13; associated with WAGR, Denys-Drash
β€’ WT2 (11p15) – Beckwith-Wiedemann syndrome
β€’ CTNNB1, WTX – Wnt pathway variants
β€’ Loss of heterozygosity (LOH) – 1p & 16q (poor prognosis)
β€’ Gain of 1q – adverse prognostic factor
β€’ TP53 – anaplastic histology
β€’ DICER1 – associated with cystic nephroma and Wilms

πŸ”Ή Investigations – Exclude Others

β€’ Urinary catecholamines (VMA/HVA) – exclude neuroblastoma
β€’ AFP, Ξ²-hCG – exclude hepatoblastoma/germ cell tumour
β€’ Chest X-ray – lung metastases
β€’ Bone scan – if clear cell sarcoma or rhabdoid suspected
β€’ Brain MRI – if rhabdoid or clear cell sarcoma
β€’ Serum LDH – may be elevated in aggressive disease

πŸ”Ή Investigations – Rule Out Complications

β€’ IVC thrombus – Doppler US, MRI/CT with contrast
β€’ Hypertension – BP monitoring; renal artery Doppler
β€’ Renal failure – serum creatinine, GFR
β€’ Pulmonary metastases – chest CT
β€’ Liver metastases – abdominal CT/MRI
β€’ Bone metastases – bone scan (if high-risk histology)
β€’ Bilateral disease – CT/MRI of both kidneys

πŸ”Ή Management – Across Organ Systems

Surgical

Radical nephrectomy – via transabdominal approach; early ligation of renal vein to prevent tumour embolisation. Lymph node sampling essential.

Chemotherapy

Risk-adapted: Vincristine + Actinomycin D (stages I–II); + Doxorubicin (stages III–IV, anaplastic). Regimen DD4A or M per COG.

Radiotherapy

Flank/abdominal radiation for stage III (residual disease, tumour spill, nodal involvement). Lung radiation for pulmonary metastases (if incomplete response).

Hypertension

ACE inhibitors (captopril, enalapril) or calcium channel blockers. Monitor BP daily; may resolve post-nephrectomy.

Nutrition

High-calorie diet, nutritional support during chemotherapy. Monitor for nausea, mucositis, and weight loss.

IVC Thrombus

Anticoagulation if indicated. Surgical thrombectomy or cardiopulmonary bypass if extending into right atrium.

Supportive Care

Transfusions (PRBC, platelets) for cytopenias. G-CSF for neutropenia. Anti-emetics, pain management.

Bilateral Wilms

Preoperative chemotherapy; nephron-sparing surgery (partial nephrectomy) to preserve renal function.

πŸ“ˆ Prognosis

  • Stage I FH: 4-yr EFS ~90–95%, OS ~100%.
  • Stage II FH: 4-yr EFS ~85–90%, OS ~95%.
  • Stage III FH: 4-yr EFS ~85–90%, OS ~95% (with RT).
  • Stage IV FH: 4-yr EFS ~80–85%, OS ~90%.
  • Anaplastic (diffuse): poorer – stage II ~80%, stage IV ~50%.
  • LOH 1p/16q: adverse prognosis; intensification with Regimen M.
  • Relapse: 15% FH, 50% anaplastic; salvage ~50–80% depending on prior therapy.

πŸ“‹ Follow‑up Schedule

  • During treatment: weekly CBC, LFTs, renal function; BP monitoring.
  • After treatment (first 2 yr): chest/abdominal imaging every 3–6 months.
  • Years 2–5: imaging every 6–12 months.
  • Late effects screening: cardiac (anthracyclines), renal function, hearing (cisplatin), secondary malignancies.
  • Genetic counselling: for syndromic patients and families.
πŸ’‘ Examiner expectation: logical differential (Wilms vs neuroblastoma vs others), systematic investigation (diagnosis β†’ aetiology β†’ exclude others β†’ complications), and a management plan covering surgery, chemotherapy, and radiation. Know the COG staging and risk-adapted therapy.
Mock OSCE Β· Wilms Tumor (Abdominal Mass) Β· Based on Wyne‑Harris, Nelson & Pediatric Clinical Advisor