During morning rounds on the inpatient hematology unit, a resident assesses a 38-year-old … — USMLE Step 2 CK

During morning rounds on the inpatient hematology unit, a resident assesses a 38-year-old male who was admitted four days ago with a new diagnosis of acute promyelocytic leukemia. He was immediately started on targeted induction therapy including a vitamin A derivative. Over the last 12 hours, the patient has developed a fever, progressive shortness of breath, and a weight gain of $3.5\text{ kg}$ . Temperature is $38.5^\circ\text{C}$ ( $101.3^\circ\text{F}$ ), blood pressure is $105/65\text{ mmHg}$ , pulse is $118/\text{min}$ , and respiratory rate is $26/\text{min}$ . Pulse oximetry shows $89\%$ on ambient air. Physical examination reveals elevated jugular venous pressure and diffuse bilateral crackles on lung auscultation. Laboratory studies show a leukocyte count of $28,000/\mu\text{L}$ , which has increased from $4,500/\mu\text{L}$ on admission. A chest radiograph demonstrates bilateral interstitial opacities and a small right-sided pleural effusion. Which of the following is the most appropriate next step in management?

A
Prescribe an intravenous loop diuretic
B
Add empiric antifungal therapy
Start therapy with high-dose corticosteroidsAnswer
D
Perform urgent therapeutic leukapheresis
E
Halt the current leukemia induction regimen

Answer

Start therapy with high-dose corticosteroids

This patient's presentation of fever, dyspnea, weight gain, pulmonary infiltrates, and leukocytosis shortly after starting all-trans retinoic acid (ATRA) for acute promyelocytic leukemia is highly characteristic of differentiation syndrome. The prompt initiation of high-dose corticosteroids, such as dexamethasone, is life-saving and constitutes the definitive next step in management.

Step-by-Step Solution

Identify the underlying diagnosis and the current treatment phase based on the clinical history.

The patient has acute promyelocytic leukemia (APL) and recently began induction therapy with a vitamin A derivative (all-trans retinoic acid).

Establishing the pharmacological context is necessary to anticipate specific drug-related complications.

Analyze the new onset of symptoms and laboratory findings.

The patient presents with fever, respiratory distress, weight gain, pulmonary edema, and a rising leukocyte count.

These findings precisely map to the diagnostic criteria for a specific systemic reaction.

Synthesize the findings to determine the correct immediate management step.

The clinical picture represents differentiation syndrome (formerly ATRA syndrome). The required intervention is immediate administration of high-dose dexamethasone.

Corticosteroids halt the severe inflammatory cytokine release causing the capillary leak and respiratory distress.

Key Concept

Differentiation syndrome is a life-threatening complication of all-trans retinoic acid therapy in acute promyelocytic leukemia. It presents with fever, respiratory distress, weight gain, and pulmonary infiltrates, and requires immediate treatment with high-dose corticosteroids.

Estimated Time:1m 15s

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