In a child with sickle cell crisis presenting with chest pain, the underlying cause is most likely occlusion of which structure?

• A. Pancreatic ducts occluded.
• B. Pulmonary microcirculation is occluded.
• C. Capillaries in the limbs are occluded.
• D. Coronary arteries occluded.

Answer: (B)

Vaso-occlusion from sickled red cells in sickle cell crisis often involves the lungs, leading to acute chest syndrome. When the pulmonary microcirculation becomes occluded, infarction and inflammation impair gas exchange and provoke chest pain, making occlusion of the pulmonary microcirculation the most likely cause in a child with chest pain during a crisis. Occlusion of pancreatic ducts would cause pancreatitis, limb capillaries would give extremity pain, and coronary arteries would suggest myocardial ischemia—less typical in pediatric sickle cell presentations and not fitting the chest-pain pattern seen here.