A 4-year-old boy from Delhi presents with a 3-week history of fever, pallor, and petechiae. On examination, he has hepatomegaly (3 cm below costal margin) and splenomegaly (4 cm). Complete blood count shows hemoglobin 7.2 g/dL, WBC 85,000/μL with 70% blasts, and platelets 35,000/μL. Peripheral blood smear confirms acute leukemia with Auer rods. What is the most appropriate next step in management?

Explanation

## Clinical Context This child presents with classic acute leukemia: fever, bleeding tendency, hepatosplenomegaly, and high WBC with blasts. The presence of Auer rods confirms acute myeloid leukemia (AML). Before initiating chemotherapy, critical preparatory steps are mandatory. ## Why the Correct Answer is Best **Key Point:** Pre-chemotherapy stabilization and risk assessment are essential before induction therapy in acute leukemia to prevent life-threatening complications. The correct sequence of next steps includes: 1. **Confirm diagnosis** — bone marrow aspiration with cytochemistry (MPO, PAS, Sudan black) to classify AML subtype and guide therapy 2. **Assess for DIC** — high WBC (85,000/μL) and blasts increase thromboplastin release; coagulation profile (PT, aPTT, fibrinogen, D-dimer) is mandatory 3. **Evaluate for hyperuricemia** — leukemic burden causes spontaneous cell lysis and uric acid release 4. **Establish central venous access** — required for chemotherapy, blood products, and supportive care 5. **Initiate TLS prophylaxis** — allopurinol or rasburicase, aggressive hydration, and urine alkalinization BEFORE chemotherapy to prevent acute kidney injury **Clinical Pearl:** Tumor lysis syndrome (TLS) can occur spontaneously in high-burden leukemias but is dramatically accelerated by chemotherapy. Prophylaxis must begin *before* induction to prevent hyperkalemia, hyperphosphatemia, hypocalcemia, and acute renal failure. **High-Yield:** In pediatric acute leukemia with WBC >50,000/μL, hyperleukostasis and DIC are life-threatening risks. Pre-treatment stabilization is non-negotiable. ## Management Algorithm ```mermaid flowchart TD A[Suspected acute leukemia with high WBC]:::outcome --> B[Confirm diagnosis: BMA + cytochemistry]:::action B --> C[Assess for DIC: PT, aPTT, fibrinogen, D-dimer]:::action C --> D[Check uric acid, creatinine, electrolytes]:::action D --> E[Establish CVL]:::action E --> F[Start TLS prophylaxis: rasburicase, hydration]:::action F --> G[Induction chemotherapy]:::action G --> H[Monitor for TLS]:::outcome ``` **Mnemonic:** **BLAST** = **B**one marrow aspiration, **L**ab work (DIC, uric acid), **A**ccess (CVL), **S**tabilize (TLS prophylaxis), **T**hen treat (chemotherapy).