Common Pediatric Diseases and Disorders
Childhood cancer is rare but devastating, with distinct biology, presentation, and treatment approaches compared to adult cancers. Early recognition of warning signs is crucial for timely diagnosis and improved outcomes.
📊 Epidemiology: The Numbers
Understanding the Landscape of Childhood Cancer
Childhood cancer is rare but remains the leading cause of death by disease in children.
Incidence and Survival
- Incidence: 15-16 cases per 100,000 children per year
- New cases: 10,000-11,000 annually in US children under 15
- Leading cause: Death by disease (second overall to accidents)
- 5-year survival: >80% (dramatic improvement from <20% in 1960s)
- Annual deaths: 1,800 children still die from cancer annually in US
Age Distribution and Common Types
- Peak incidence: 0-4 years
- Second peak: 15-19 years (adolescent/young adult cancers)
- Most common:
- Leukemias (28%): ALL, AML
- Brain and CNS tumors (26%)
- Lymphomas (10%)
- Neuroblastoma (6%)
- Wilms tumor (5%)
🎯 Survival Success Story
One of medicine's greatest success stories - overall 5-year survival has increased from <20% in the 1960s to >80% today through cooperative group trials, risk stratification, multimodal therapy, and supportive care advances.
🆚 Childhood vs. Adult Cancers
Fundamentally Different Diseases
Childhood cancers differ from adult cancers in types, causes, biology, and often outcomes.
| Aspect | Adult Cancers | Childhood Cancers |
|---|---|---|
| Mutations | 50-100 accumulated mutations over decades | 2-10 mutations |
| Origin | Epithelial (lung, colon, breast, prostate) | Embryonal (developing tissues) |
| Causes | Environmental exposures, lifestyle factors | Rapid growth, genetic predisposition more common |
| Environmental Role | Major role | Smaller role |
Genetic predisposition: About 10% of childhood cancers have identifiable genetic causes including Li-Fraumeni syndrome (TP53), Retinoblastoma (RB1), Neurofibromatosis (NF1), Beckwith-Wiedemann, Down syndrome (20x increased leukemia risk), and DNA repair defects.
🚩 Red Flags: When to Suspect Cancer
Recognizing the Warning Signs
Unlike adults who present with mass-related symptoms, children often present with non-specific symptoms that mimic common childhood illnesses. High index of suspicion is crucial!
Constitutional Symptoms
- Fever: Prolonged (>2 weeks), no clear source, doesn't respond to antibiotics
- Weight loss: Unexplained, failure to thrive, loss of appetite
- Fatigue: Persistent, worsening, activity limitation
- Pallor: Progressive, associated with fatigue, weakness
Specific Warning Signs
- Unexplained mass or swelling: Painless lymphadenopathy (>2 cm, firm, fixed)
- Bone pain: Persistent, progressive, worse at night, awakens from sleep
- Headaches: New onset, morning headaches with vomiting, progressive
- Neurological changes: Developmental regression, seizures, vision changes
- Easy bruising or bleeding: Petechiae, purpura, unusual bruising
📝 "CHILD HOOD" Mnemonic for Cancer Warning Signs
- Continued, unexplained weight loss
- Headaches with vomiting (especially morning)
- Increased swelling or persistent pain in bones, joints, back, legs
- Lump or mass in abdomen, neck, chest, pelvis, armpits
- Development of excessive bruising, bleeding, or rash
- Hematologic changes (anemia, thrombocytopenia)
- Ocular changes (white pupil, new strabismus, vision loss, proptosis)
- Ongoing infections
- Daily fevers of unknown origin
Clinical pearl: "Unexplained persistent symptoms warrant investigation." Don't dismiss bone pain, headaches, or lymphadenopathy as "growing pains" or "viral" without thorough evaluation.
🩸 Leukemia: Cancer of the Blood
Acute Lymphoblastic Leukemia (ALL)
The most common childhood cancer (25% of all childhood cancers) with peak incidence at 2-5 years.
Pathophysiology and Classification
- Pathophysiology: Malignant transformation of lymphoid precursor cells in bone marrow
- B-cell ALL: 85% (most common)
- T-cell ALL: 15% (worse prognosis, more mediastinal masses, CNS involvement)
- Good prognosis genetics: Hyperdiploidy (>50 chromosomes), t(12;21) ETV6-RUNX1
- Poor prognosis genetics: Hypodiploidy (<44 chromosomes), t(9;22) Philadelphia chromosome
Clinical Presentation
- Bone marrow failure: Anemia, thrombocytopenia, neutropenia
- Bone pain: From marrow expansion and periosteal infiltration
- Organomegaly: Hepatosplenomegaly, lymphadenopathy
- Other: Fever, mediastinal mass (T-cell ALL), CNS involvement
Laboratory Findings
- Complete Blood Count: WBC can be low, normal, or very high (up to 200,000+); low hemoglobin; low platelets; blast cells on peripheral smear
- Bone Marrow Aspirate/Biopsy: ≥25% lymphoblasts (diagnostic)
- Other: Elevated LDH, uric acid (tumor lysis risk)
Treatment Phases
- Induction (4-6 weeks): Achieve remission (blast cells <5% in marrow)
- Consolidation (4-8 weeks): Intensify treatment, prevent relapse
- Interim Maintenance
- Delayed Intensification: Repeat induction-like chemotherapy
- Maintenance (1.5-2.5 years total therapy): Daily 6-mercaptopurine, weekly methotrexate
CNS Prophylaxis: Intrathecal chemotherapy during all phases to prevent CNS relapse (sanctuary site)
Prognosis
- Overall 5-year survival: 85-90%
- Standard risk: >90%
- High risk: 70-80%
- Relapsed: 30-50%
Acute Myeloid Leukemia (AML)
Accounts for 15-20% of childhood leukemias with more heterogeneous presentation than ALL.
Risk Factors and Presentation
- Risk factors: Down syndrome (10-20x increased risk), prior chemotherapy, radiation exposure
- Clinical presentation: Similar to ALL but with more bleeding/coagulopathy
- Special findings: Gum hypertrophy (M5—monocytic), chloromas
Special Subtype: APL (M3)
- Genetics: t(15;17) translocation
- Complication: DIC common (can be fatal)
- Treatment: All-trans retinoic acid (ATRA) + arsenic trioxide
- Cure rate: >80% — one of the most curable leukemias!
Tumor Lysis Syndrome
Risk: High in leukemias with very high WBC counts
Pathophysiology: Massive cell death releases intracellular contents causing hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, acute kidney injury
Prevention: Aggressive IV hydration, allopurinol or rasburicase, close electrolyte monitoring
Clinical pearl: "Tumor lysis syndrome prevention is easier than treatment." Aggressive hydration and allopurinol/rasburicase before starting chemotherapy.
🧠 Brain and CNS Tumors
Second Most Common Childhood Cancer (26%)
Brain tumors are the most common solid tumor in children with varied presentations based on location and type.
Classification by Location
- Infratentorial (60%): Below tentorium (cerebellum, brainstem)
- Supratentorial (40%): Above tentorium (cerebral hemispheres)
Common Types
- Astrocytoma (low-grade and high-grade)
- Medulloblastoma
- Ependymoma
- Brainstem glioma
- Craniopharyngioma
General Clinical Presentation
- Increased Intracranial Pressure: Morning headaches, vomiting (often projectile), papilledema, altered mental status
- Focal Neurological Signs: Weakness, sensory changes, ataxia, cranial nerve palsies, seizures
- Behavioral/Developmental Changes: Personality changes, school performance decline, developmental regression
Clinical pearl: "Morning headaches with vomiting = brain tumor until proven otherwise." Especially if progressive.
Medulloblastoma
Most common malignant brain tumor in children with peak age 5-7 years.
- Location: Cerebellum (posterior fossa)
- Clinical features: Morning headaches, vomiting (ICP), ataxia, clumsiness, truncal instability
- Treatment: Maximal safe surgical resection, craniospinal radiation, chemotherapy
- Prognosis: 5-year survival 70-80%
Low-Grade Glioma (Astrocytoma)
Most common brain tumor overall in children with peak age 5-10 years.
- Location: Various (cerebellum, optic pathway, brainstem)
- Clinical features: Depend on location, often indolent and slow-growing
- Special type: Pilocytic astrocytoma (most benign, cerebellar most common)
- Treatment: Complete surgical resection if possible (curative!)
- Prognosis: Excellent if resectable (>90% cure)
Brainstem Glioma
Located in pons (most common), midbrain, or medulla with peak age 5-10 years.
- Classic triad: Cranial nerve palsies (especially CN VI, VII), ataxia, long tract signs
- Diffuse Intrinsic Pontine Glioma (DIPG): Most common and most devastating, infiltrates pons, inoperable
- Treatment: Radiation (palliative), chemotherapy (limited benefit)
- Prognosis: DIPG median survival 9-12 months, nearly 100% fatal
Clinical pearl: "Brainstem gliomas (DIPG) have the worst prognosis of childhood cancers." Nearly universally fatal. Honest conversations with families essential.
Diagnosis of Brain Tumors
- Imaging: MRI brain with contrast (gold standard), MRI spine if risk of spinal mets
- Biopsy/Resection: Tissue diagnosis, extent of resection affects prognosis
- Lumbar Puncture: Check CSF for malignant cells ONLY after imaging (risk of herniation)
🔑 High-Yield Summary - Part 1
| Cancer Type | Key Features | Clinical Pearls |
|---|---|---|
| ALL | Most common childhood cancer, peak 2-5 years, B-cell (85%) | Excellent prognosis (85-90% cure), requires 2-3 years treatment |
| AML | 15-20% of leukemias, APL subtype highly curable with ATRA | High tumor lysis risk, monitor for DIC in APL |
| Medulloblastoma | Most common malignant brain tumor, cerebellar location | Requires craniospinal radiation, 70-80% survival |
| Low-Grade Glioma | Most common brain tumor overall, often pilocytic astrocytoma | Surgical resection curative if possible (>90% cure) |
| Brainstem Glioma | DIPG most devastating, classic triad of symptoms | Nearly universally fatal (median survival 9-12 months) |
🎯 Key Takeaways - Part 1
- Childhood cancers are fundamentally different from adult cancers in biology, causes, and presentation
- Overall survival has dramatically improved from <20% in 1960s to >80% today
- Early recognition of warning signs using the "CHILD HOOD" mnemonic is crucial
- ALL is the most common childhood cancer with excellent prognosis (85-90% cure)
- Brain tumors are the most common solid tumors with varied presentations based on location
- DIPG has the worst prognosis of childhood cancers (median survival 9-12 months)
- Tumor lysis syndrome prevention is critical in leukemias with high WBC counts
- Morning headaches with vomiting should raise suspicion for brain tumors