Pediatric Hematology and Oncology

A pediatric hematology and oncology team is reviewing diagnostic studies for several newly admitted children. Match each characteristic cytogenetic or molecular finding with its corresponding pediatric malignancy.

A 4-year-old girl is brought to the clinic by her parents due to a two-week history of worsening fatigue, spontaneous bruising on her legs, and intermittent low-grade fevers. Physical examination reveals generalized lymphadenopathy and mild hepatosplenomegaly. The physician suspects acute lymphoblastic leukemia (ALL). Arrange the following diagnostic steps in the most appropriate chronological order, from initial screening to definitive staging.

A crucial component of pediatric hematology and oncology is managing the long-term survivorship of patients exposed to cytotoxic chemotherapy. Match the following chemotherapeutic classes commonly used in pediatric malignancies to their precise mechanism of target-organ toxicity or associated secondary malignancy.

A seven-year-old girl with a history of retroperitoneal neuroblastoma is brought to the emergency department due to severe, worsening mid-back pain for the past three days and new-onset difficulty walking over the last twelve hours. Her parents report she has not voided urine since yesterday evening. Vital signs are within normal limits for her age. Neurologic examination reveals grade three out of five motor strength in the bilateral lower extremities, hyperreflexia at the patellae, and decreased sensation to light touch below the umbilicus. The bladder is palpably distended. Arrange the following management steps in the most appropriate chronological sequence for this patient's suspected complication.

A $6$-year-old boy with sickle cell disease (HbSS) is brought to the emergency department due to increasing fatigue and generalized weakness over the past $48$ hours. One week ago, he had a low-grade fever accompanied by a bright red "slapped-cheek" facial rash that has since faded. He reports no pain in his chest, abdomen, or extremities. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $95/60 \text{ mm Hg}$, pulse is $135/\text{min}$, and respirations are $22/\text{min}$. Physical examination reveals marked conjunctival pallor and a grade $2/6$ systolic flow murmur at the left upper sternal border. The abdomen is soft and non-tender, and the spleen is not palpable. Laboratory studies show:

Which of the following is the most likely underlying mechanism for this patient's acute hematologic presentation?

A $4$-year-old boy is evaluated in the pediatric oncology clinic for an urgent follow-up. He was diagnosed with standard-risk B-cell acute lymphoblastic leukemia (ALL) eight months ago and is currently in the maintenance phase of chemotherapy. Today, he has mild rhinorrhea but is otherwise active and playful. His mother reports that the patient spent the weekend with his $6$-year-old cousin. Three days after the exposure, the cousin developed a low-grade fever and a diffuse vesicular rash that was subsequently diagnosed as chickenpox by a pediatrician. The patient has never had chickenpox and missed his routine preschool immunizations due to his cancer diagnosis. The patient's temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $95/60 \text{ mmHg}$, heart rate is $100/\text{min}$, and respiratory rate is $20/\text{min}$. Physical examination reveals clear lungs, normal heart sounds, and no skin lesions. Laboratory studies show a leukocyte count of $3,200/\text{mm}^3$ with an absolute neutrophil count of $1,600/\text{mm}^3$. The mother asks how to protect her son from the exposure. Which of the following is the most appropriate next step in management?

A 6-year-old boy is newly diagnosed with Burkitt lymphoma. He presents with a large abdominal mass, and laboratory studies reveal a significantly elevated serum lactate dehydrogenase (LDH) and uric acid level. The oncology team is preparing to begin his treatment but must first address his high risk for developing tumor lysis syndrome (TLS). Arrange the following management steps in the most appropriate sequential order, starting from the most critical initial preventive measure to the intervention reserved for severe, refractory complications.

A 9-year-old boy is hospitalized for the management of acute myeloid leukemia. He recently completed his first cycle of induction chemotherapy. Five days ago, he developed a fever of $39.4^\circ C$ ($102.9^\circ F$) and was found to have an absolute neutrophil count (ANC) of $120/\mu L$. Blood and urine cultures were drawn, and empiric intravenous cefepime was initiated.

Today (hospital day 6 of fever), his temperature remains elevated at $39.2^\circ C$ ($102.6^\circ F$). His blood pressure is 105/65 mmHg, and heart rate is 110/min. Physical examination reveals a clean central venous catheter site with no surrounding erythema or tenderness. The lungs are clear to auscultation, and there are no oral lesions or skin rashes.

Laboratory studies today show:

Blood cultures from admission and from two days ago have shown no growth. A chest radiograph reveals no infiltrates. Which of the following is the most appropriate next step in management?

A $9$-year-old boy with a known history of sickle cell anemia (HbSS) is brought to the emergency department by his parents. $1$ hour ago, he suddenly developed slurred speech and weakness in his right arm and leg. On presentation, his temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, heart rate is $105/\text{min}$, and respiratory rate is $18/\text{min}$. Physical examination reveals an alert child with a right-sided facial droop and dense right-sided hemiparesis. Arrange the following management steps in the most appropriate chronological sequence for this patient.

A 7-year-old boy with newly diagnosed Burkitt lymphoma is started on induction chemotherapy. Within 24 hours, he develops lethargy, nausea, and decreased urine output. Laboratory studies show hyperkalemia, hyperphosphatemia, hypocalcemia, and elevated serum uric acid levels. Arrange the following pathophysiologic events in the correct chronological order leading to this patient's acute kidney injury.

A 2-year-old boy with sickle cell disease (HbSS) is brought to the emergency department by his parents due to the sudden onset of severe lethargy, pallor, and abdominal swelling. His parents report that he was playing normally this morning but became progressively weak and poorly responsive over the past 3 hours. His temperature is 37.1°C (98.8°F), heart rate is 165/min, respiratory rate is 40/min, and blood pressure is 75/40 mm Hg. Physical examination reveals marked conjunctival pallor and a massively enlarged, firm spleen extending into the left lower quadrant. Laboratory studies show a hemoglobin of 3.8 g/dL, platelets of 80,000/mm³, and a reticulocyte count of 18%. What is the most appropriate next step in the management of this patient?

Match each characteristic peripheral blood smear or microscopic finding with the most likely corresponding pediatric hematologic or oncologic diagnosis.

A 4-year-old boy is brought to the pediatrician's office by his parents after they noticed a red, pinpoint rash on his legs and arms this morning. The patient had a mild upper respiratory tract infection two weeks ago but has completely recovered. He is currently active and well-appearing. His temperature is 37.0°C (98.6°F), blood pressure is 95/60 mmHg, pulse is 90/min, and respirations are 20/min. Physical examination reveals scattered petechiae and purpura over the lower extremities. There is no hepatosplenomegaly, lymphadenopathy, or joint swelling. Laboratory evaluation shows:

Hemoglobin: 12.2 g/dL
Leukocyte count: 7,500/mm³
Platelet count: 15,000/mm³
Prothrombin time: 11 seconds (normal: 11-15 seconds)
Activated partial thromboplastin time: 30 seconds (normal: 25-40 seconds)

Which of the following is the most likely diagnosis?

A 14-year-old boy is evaluated in the emergency department for a 3-day history of progressively worsening headache, blurred vision, and shortness of breath. Physical examination reveals pale conjunctivae, scattered petechiae, and bilateral retinal hemorrhages. Vital signs are temperature 37.8°C (100.0°F), heart rate 132/min, respiratory rate 28/min, and blood pressure 110/65 mmHg. Pulse oximetry shows 92% on room air.

Laboratory studies show:
Leukocytes: 380,000/mm³ (90% myeloblasts)
Hemoglobin: 5.2 g/dL
Platelets: 22,000/mm³
Uric acid: 9.8 mg/dL
Potassium: 4.8 mEq/L
Creatinine: 1.1 mg/dL

Arrange the following interventions in the most appropriate chronological sequence to safely manage this patient's acute presentation.

A 16-month-old boy is brought to the pediatric clinic for a routine well-child evaluation. His mother mentions that he is a picky eater and refuses most solid foods. His diet consists predominantly of $32$ to $40$ ounces (approximately $950$ to $1200 \text{ mL}$) of whole cow's milk daily, supplemented only by small amounts of crackers. He is active but occasionally appears more fatigued than his siblings did at this age. Vital signs are within normal limits. Physical examination reveals conjunctival pallor but no hepatosplenomegaly or lymphadenopathy. Laboratory studies show:

Hemoglobin: $8.4 \text{ g/dL}$
Mean corpuscular volume (MCV): $66 \text{ fL}$
Red cell distribution width (RDW): $19\%$ (normal: $11.5\% - 14.5\%$)
Reticulocyte count: $1.0\%$

Which of the following is the most likely diagnosis?

Match each pediatric hematologic or oncologic diagnosis with its most characteristic peripheral blood smear finding.

A 20-month-old boy is brought to the pediatric emergency department due to a 7-day history of a brassy cough and a rapid decline in his respiratory status over the past 24 hours. The parents report he has been increasingly restless and absolutely refuses to lie flat, insisting on being held in an upright, leaning-forward position. On presentation, his temperature is $37.5^\circ\text{C}$ ($99.5^\circ\text{F}$), heart rate is $158/\text{min}$, respiratory rate is $56/\text{min}$, and blood pressure is $92/54\text{ mmHg}$. Oxygen saturation is $90\%$ on a non-rebreather mask. Physical examination reveals prominent cervical lymphadenopathy, facial plethora with distended neck veins, severe suprasternal retractions, and a biphasic stridor. A portable bedside chest radiograph demonstrates a markedly widened superior mediastinum with severe extrinsic compression of the distal trachea, narrowing the airway lumen to approximately $2\text{ mm}$. The child is highly agitated and exhibits worsening work of breathing. Which of the following is the most appropriate next step in management?

A 9-year-old boy with a known history of sickle cell anemia is brought to the emergency department by his parents due to fever, cough, and severe chest pain that started yesterday. His temperature is $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$), heart rate is $120/\text{min}$, blood pressure is $105/65\text{ mmHg}$, and respiratory rate is $30/\text{min}$. Oxygen saturation is $89\%$ on room air. Physical examination reveals crackles and decreased breath sounds in the right lower lung field. A chest radiograph demonstrates a new right lower lobe infiltrate. Which of the following is the most appropriate next step in management?

Evaluate the following clinical profiles of pediatric patients presenting with cytopenias. Assign each patient to the fundamental pathophysiologic mechanism or genetic defect that best explains their constellation of clinical and laboratory findings.

A 14-month-old boy is brought to the clinic by his parents because of a swollen and tender right knee that developed yesterday. The patient recently started walking independently. The parents deny any major trauma but note that he frequently bumps into furniture. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), pulse is $110/\text{min}$, and respirations are $24/\text{min}$. Physical examination reveals a moderately swollen, warm right knee with a limited range of motion due to pain. There are also several large ecchymoses on his shins. Laboratory evaluation shows:

Hemoglobin: $11.8 \text{ g/dL}$
Platelet count: $310,000/\text{mm}^3$
Prothrombin time (PT): $12 \text{ seconds}$ (Normal: $11-15 \text{ seconds}$)
Activated partial thromboplastin time (aPTT): $72 \text{ seconds}$ (Normal: $25-40 \text{ seconds}$)

Which of the following is the most likely underlying cause of this patient's clinical presentation?