Pediatric Neoplasia
Core concepts
Know the pediatric tumor spectrum and its contrast with adult cancers: embryonal tumors (neuroblastoma, Wilms tumor, hepatoblastoma, medulloblastoma, retinoblastoma) versus hematologic malignancies (ALL, lymphoma). Understand translocation-defined tumors and their diagnostic ancillary tests (e.g., Ewing sarcoma, alveolar rhabdomyosarcoma, synovial sarcoma). Recognize small round blue cell tumor differential and how immunohistochemistry resolves it.
Master staging and prognostic features for high-yield entities: neuroblastoma (MYCN amplification, Shimada histology, age), Wilms tumor (favorable vs anaplastic histology), and retinoblastoma (RB1 genetics, heritability). Understand tumor predisposition syndromes (Li-Fraumeni, Beckwith-Wiedemann, NF1).
Traps
Examiners test age as a diagnostic clue and the overlap of small round blue cell tumors. Another trap: confusing favorable vs unfavorable histology in Wilms and neuroblastoma. Do not assume all pediatric tumors are curable or that staging systems are interchangeable across tumor types.
Worked example / rule of thumb
A young child with an abdominal mass, elevated catecholamines, and MYCN amplification: neuroblastoma with unfavorable biology. Rule of thumb: "Small round blue cell → order IHC panel before committing; translocation → confirm molecularly."