American Board of Internal Medicine (ABIM) Certification Practice Exam

What characterizes differentiation syndrome from ATRA and ATO treatment?

1. Hypotension and bradycardia

2. Hypoxemia, pulmonary infiltrates, and fever

3. Severe headaches and dizziness

4. Nausea and vomiting only

The correct answer is: Hypoxemia, pulmonary infiltrates, and fever

Differentiation syndrome is a well-recognized complication associated with the treatment of acute promyelocytic leukemia (APL) using all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Characteristically, this syndrome presents with a constellation of symptoms that can include hypoxemia, pulmonary infiltrates, and fever. The mechanism behind differentiation syndrome involves a rapid differentiation of leukemic cells, which can lead to an inflammatory response in the lungs and other organs. Patients may exhibit respiratory distress due to pulmonary infiltrates, resulting in low oxygen levels (hypoxemia). The presence of fever along with these pulmonary symptoms is also indicative of this syndrome and helps differentiate it from other treatment-related side effects. While hypotension and bradycardia, severe headaches and dizziness, and nausea and vomiting can occur in various clinical scenarios, they do not specifically describe the hallmark features of differentiation syndrome seen with ATRA and ATO treatment. Thus, the combination of respiratory symptoms and fever distinctly characterizes differentiation syndrome, making it essential for clinicians to recognize this condition for prompt management.