A 2-year-old child with failure to thrive, recurrent wheezing, and pulmonary infections. Of the following, the LEAST common cause of his illness is

Correct Answer: A

Rationale: Asthma is less likely to cause failure to thrive compared to aspiration, food allergy, cystic fibrosis, or immunodeficiency, which directly affect nutrition and respiratory function.

Correct Answer: C

Rationale: Late-phase reactions to venom include serum sickness, vasculitis, nephrotic syndrome, and hemolytic anemia, but encephalopathy is not a common delayed reaction to venom exposure.

Correct Answer: C

Rationale: Renal tubular acidosis causes normal anion gap metabolic acidosis, unlike other conditions listed, which lead to a high anion gap due to acid accumulation.

Correct Answer: D

Rationale: All statements are true; CNS leukemia has a poor prognosis, causes increased ICP, is prone to relapse, and can lead to cranial nerve palsies.

Correct Answer: A

Rationale: Osteoarthritis is the most common form of arthritis and typically affects joints through wear and tear over time.