Tumors of childhood and their characteristics (neuroblastoma, retinoblastoma, Wilms tumor)

1. Childhood tumors — general features

Childhood malignancies differ from adult ones: they arise in hematopoietic, neural, and soft tissue (not lung/prostate/colon), show a close link between teratogenesis and oncogenesis, often have predisposing genes/syndromes, may spontaneously regress or mature, and are composed of small, undifferentiated “blastema” cells.

Benign: hemangioma (most common infant tumor; port-wine skin lesions), lymphangioma, sacrococcygeal teratoma (10% with congenital midline defects).

2. Neuroblastoma

• Tumor of sympathetic ganglia + adrenal medulla; sporadic or AD.
• Can spontaneously regress/mature; large masses show necrosis/hemorrhage.
• Histology: small dark cells, scant cytoplasm, neuropil background, Homer-Wright pseudo-rosettes (no central lumen). Ganglioneuroblastoma / ganglioneuroma = more mature variants.
• Prognosis: stage + age (better <18 months); stage 4S = small primary + liver/skin/marrow mets, good prognosis. N-MYC amplification = poor prognosis.
• Diagnosis: ↑ urinary catecholamines (VMA, HVA).

3. Retinoblastoma

• Most common malignant childhood eye tumor; often congenital, bilateral/multifocal in familial cases.
• Germline RB1 mutation (two-hit); familial → bilateral + ↑ risk of second primaries (osteosarcoma). Sporadic → unilateral/unifocal.
• Histology: small round blue cells; Flexner-Wintersteiner rosettes (true central lumen — contrast neuroblastoma).
• Clinical: leukocoria (“cat’s eye reflex”), strabismus, poor vision; fatal if untreated.

4. Wilms tumor (nephroblastoma)

• Most common childhood renal tumor, age 2–5.
• Associated with WT1 anomalies: WAGR, Denys-Drash; and Beckwith-Wiedemann (IGF-2 imprinting loss → overgrowth).
• Histology: triphasic — blastemal + stromal + epithelial (abortive tubules/glomeruli). Anaplasia (p53) = worse, chemo-resistant. Nephrogenic rests = precursor.
• Clinical: large palpable abdominal mass; excellent prognosis with nephrectomy + chemo.

💡 High-yield: Neuroblastoma — adrenal/sympathetic, Homer-Wright pseudo-rosettes, ↑VMA/HVA, N-MYC = poor prognosis, 4S regresses. Retinoblastoma — RB1 two-hit, Flexner-Wintersteiner rosettes (true lumen), leukocoria. Wilms — WT1 (WAGR, Denys-Drash, Beckwith-Wiedemann), triphasic histology, great prognosis.