## **Core Concept**
The question revolves around the management of a complication arising in a patient with acute promyelocytic leukemia (APL), specifically the development of tachypnea, fever, and pulmonary infiltrates, which are suggestive of **acute respiratory distress syndrome (ARDS)**, possibly due to **differentiation syndrome (DS)**, formerly known as **retinoic acid syndrome**. This condition is a life-threatening complication that can occur in patients with APL, particularly after the initiation of treatment with all-trans retinoic acid (ATRA) or arsenic trioxide.

## **Why the Correct Answer is Right**
The correct approach to managing suspected differentiation syndrome in a patient with APL involves the immediate discontinuation of the offending agent (if applicable) and the initiation of **corticosteroids**, such as dexamethasone, as a first-line treatment. This condition is a medical emergency. The use of corticosteroids helps to reduce the inflammation and prevent further complications. Supportive care, including oxygen therapy and mechanical ventilation if necessary, is also crucial. The correct answer likely involves the administration of corticosteroids.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Without knowing the specifics of option A, we can infer that if it does not involve corticosteroids or appropriate supportive care, it would be incorrect.
- **Option B:** Similarly, if option B suggests a treatment that does not address the acute inflammation and respiratory distress associated with differentiation syndrome, it would be incorrect.
- **Option C:** If option C proposes a treatment that might be beneficial in other contexts but not directly addressing the differentiation syndrome or ARDS, such as antibiotics without addressing the root cause, it would be incorrect.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **differentiation syndrome** can occur in patients with APL treated with ATRA or arsenic trioxide, and early recognition and treatment with **corticosteroids** are crucial to prevent mortality. Clinicians should have a high index of suspicion for this syndrome in patients with APL who develop respiratory distress, fever, and pulmonary infiltrates after starting treatment.

## **Correct Answer:** D. Administer corticosteroids.