# Clinical Cases: Pediatric Hematology and Oncology

## Case 1: Sickle Cell Disease with Acute Chest Syndrome

### Patient Demographics
- **Age:** 8-year-old male
- **Sex:** Male

### Chief Complaint
"He has chest pain, fever, and trouble breathing."

### History of Present Illness
An 8-year-old male with known sickle cell disease (HbSS) presents with 2 days of progressive chest pain, fever, and shortness of breath. He was admitted 4 days ago for a vaso-occlusive pain crisis affecting his back and legs, which was being managed with IV fluids and morphine. Yesterday, he developed a new cough and fever to 38.9°C. Today, he has worsening chest pain, especially with deep breathing, and his oxygen saturation has dropped. He has a history of 3 previous vaso-occlusive crises and one prior episode of acute chest syndrome at age 5. He takes hydroxyurea 20 mg/kg daily and folic acid. He has not yet started chronic transfusion therapy.

### Physical Examination
- **General:** Ill-appearing, tachypneic child in moderate respiratory distress
- **Vital signs:** Temp 39.2°C, HR 130 bpm, RR 32/min, SpO2 88% on room air, BP 100/65 mmHg
- **HEENT:** Pale conjunctivae, icteric sclerae
- **Cardiovascular:** Tachycardic, II/VI systolic flow murmur
- **Respiratory:** Decreased breath sounds at right base, dullness to percussion, crackles on right
- **Abdomen:** Soft, spleen not palpable (auto-infarcted)
- **Extremities:** No acute joint swelling, no dactylitis

### Workup
- **CBC:** WBC 18,500/μL, Hgb 6.8 g/dL (baseline 8.5), Platelets 380,000/μL, Reticulocytes 12%
- **CMP:** Normal
- **LDH:** 850 U/L (elevated)
- **Chest X-ray:** New right lower lobe infiltrate with small pleural effusion
- **ABG:** pH 7.35, pCO2 32 mmHg, pO2 58 mmHg on room air

### Diagnosis
**Acute chest syndrome complicating vaso-occlusive crisis**

### Clinical Reasoning
This patient meets the definition of acute chest syndrome: new pulmonary infiltrate on chest X-ray with at least one of fever, respiratory symptoms, or hypoxia, in a patient with sickle cell disease. ACS is the leading cause of death in sickle cell disease. The pathophysiology is multifactorial, including vaso-occlusion in the pulmonary vasculature, infection, and fat embolism from bone marrow infarction. The worsening anemia (drop from baseline of 8.5 to 6.8) reflects both hemolysis and acute illness. This case illustrates that ACS often develops during hospitalization for vaso-occlusive crisis.

### Management
1. **Respiratory support:** Supplemental oxygen to maintain SpO2 >95%; incentive spirometry every 2 hours while awake
2. **Transfusion:** Simple transfusion to Hgb 10 g/dL or exchange transfusion to reduce HbS to <30% if severe (exchange preferred given severity)
3. **Antibiotics:** Ceftriaxone plus azithromycin (cover typical and atypical organisms)
4. **Bronchodilators:** Albuterol if wheezing present
5. **Pain management:** Continue analgesia but monitor for respiratory depression
6. **VTE prophylaxis:** Consider given hypercoagulable state
7. **Long-term management:** Discuss chronic transfusion program or optimizing hydroxyurea dose; consider referral for hematopoietic stem cell transplant evaluation

### Clinical Image
![Sickle cells blood smear](case_01_image.jpg)

**Image Description:** Peripheral blood smear showing sickle-shaped red blood cells characteristic of sickle cell disease, demonstrating the abnormal hemoglobin polymerization that causes vaso-occlusion.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Sickle_cells.jpg
**License:** CC BY-SA 3.0

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## Case 2: Acute Lymphoblastic Leukemia

### Patient Demographics
- **Age:** 4-year-old male
- **Sex:** Male

### Chief Complaint
"He's been tired, bruising easily, and has had fevers."

### History of Present Illness
A 4-year-old previously healthy male is brought in with 3 weeks of progressive fatigue, decreased appetite, and intermittent fevers. His parents have noticed increased bruising, particularly on his legs, and bleeding from his gums when brushing teeth. He has been complaining of leg pain that wakes him at night. He has had no recent illnesses or sick contacts. He was in his usual state of good health until 3 weeks ago when his preschool teacher noted he seemed tired and was not playing as actively as usual.

### Physical Examination
- **General:** Pale, fatigued-appearing child
- **Vital signs:** Temp 38.1°C, HR 110 bpm, RR 22/min, BP 95/60 mmHg
- **HEENT:** Pale conjunctivae, petechiae on soft palate, gingival bleeding
- **Lymph nodes:** Bilateral cervical lymphadenopathy (multiple 1-2 cm nodes), bilateral axillary and inguinal lymphadenopathy
- **Cardiovascular:** Tachycardic, II/VI systolic flow murmur
- **Respiratory:** Clear to auscultation
- **Abdomen:** Hepatomegaly (liver 4 cm below costal margin), splenomegaly (spleen 5 cm below costal margin)
- **Extremities:** Multiple ecchymoses on lower extremities, tenderness to palpation of tibias
- **Skin:** Scattered petechiae

### Workup
- **CBC:** WBC 45,000/μL, Hgb 6.2 g/dL, Platelets 18,000/μL
- **Peripheral smear:** 65% lymphoblasts with high N:C ratio, scant cytoplasm
- **CMP:** Na 136, K 4.8, BUN 22, Cr 0.6, LDH 1,850 U/L, Uric acid 8.5 mg/dL
- **Coagulation studies:** PT/INR normal, PTT normal, Fibrinogen normal
- **Bone marrow aspirate:** 92% lymphoblasts; Flow cytometry: CD10+, CD19+, TdT+ (B-cell precursor ALL)
- **Cytogenetics:** High hyperdiploidy (favorable)
- **Lumbar puncture:** No blasts in CSF (CNS negative)
- **Chest X-ray:** No mediastinal mass

### Diagnosis
**B-cell precursor acute lymphoblastic leukemia, standard risk**

### Clinical Reasoning
This child presents with the classic constellation of ALL: pancytopenia causing fatigue/pallor (anemia), bruising/petechiae/bleeding (thrombocytopenia), and fever (neutropenia). Lymphoblasts in the peripheral blood and bone marrow confirm the diagnosis. The bone pain reflects marrow expansion. Hepatosplenomegaly and lymphadenopathy result from leukemic infiltration. Risk stratification is favorable: age 1-10 years, WBC <50,000, B-cell immunophenotype, favorable cytogenetics (hyperdiploidy), and CNS-negative. The elevated LDH and uric acid indicate high cell turnover and risk for tumor lysis syndrome with treatment initiation.

### Management
1. **Tumor lysis syndrome prevention:** IV fluids 3 L/m²/day, allopurinol or rasburicase, monitor electrolytes Q6h
2. **Transfusion support:** Packed RBCs for anemia, platelets to maintain >10,000 (or >50,000 for procedures)
3. **Infection prevention:** Neutropenic precautions; low threshold for empiric antibiotics if febrile
4. **Chemotherapy:** Induction therapy per COG protocol (vincristine, dexamethasone, PEG-asparaginase, +/- daunorubicin)
5. **Central line placement:** For chemotherapy administration
6. **Family support:** Social work, child life services, education about treatment plan
7. **Expected outcome:** >95% remission rate with induction; overall survival >90% for standard-risk B-ALL

### Clinical Image
![Peripheral blood smear with leukemia](case_01_image.jpg)

**Image Description:** Peripheral blood smear demonstrating abnormal blood cells, illustrating the hematologic findings in pediatric malignancies.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Sickle_cells.jpg
**License:** CC BY-SA 3.0