A 5-year-old boy develops hepatosplenomegaly and lymphadenopathy since early onset childhood with high spiking fevers and been treated with anti-inflammatory drugs. You suspect macrophage activation syndrome (MAS). The BEST test that distinguishes MAS from a flare of the primary disease is

Correct Answer: D

Rationale: Hemophagocytosis in the bone marrow is the hallmark of MAS.

Correct Answer: B

Rationale: A VSD murmur is holosystolic and shares characteristics with mitral regurgitation, typically best heard at the left lower sternal border.

Correct Answer: A

Rationale: These behaviors are classified as habit disorders, which often serve as self-soothing mechanisms to relieve tension or anxiety. They are not necessarily indicative of poor parenting or tics.

Correct Answer: D

Rationale: MAS typically occurs in term or post-term infants, not preterm or near-term infants. The other statements are true regarding MAS.

Correct Answer: C

Rationale: Sitting erect without support is a developmental milestone usually achieved by 8 months.