Most Common Cause of Acute Chest Syndrome in SCD
Key Point
Pulmonary infarction due to vaso-occlusion is the most common cause of acute chest syndrome (ACS) in sickle cell disease, accounting for approximately 50–70% of cases.
Pathophysiology of ACS
Acute chest syndrome results from:
- 1.
Vaso-occlusion of pulmonary vessels → pulmonary infarction
- 2.
Fat embolism from bone marrow necrosis (second most common)
- 3.
Acute infection (bacterial or viral)
- 4.
In situ thrombosis
Clinical Features of ACS
Differential Causes of ACS
| Cause | Frequency | Mechanism | Key Feature |
|---|
| Pulmonary infarction | 50–70% | Vaso-occlusion | Wedge-shaped infiltrate |
| Fat embolism | 10–15% | Bone marrow necrosis | Petechial rash, thrombocytopenia |
| Infection | 10–20% | Bacterial/viral pneumonia | Positive culture, focal consolidation |
| In situ thrombosis | Rare | Endothelial injury | Elevated D-dimer |
High-YieldNEET PG
ACS is a medical emergency in SCD and is the second leading cause of death (after stroke) in adult patients with SCD.
Clinical Pearl
Fat embolism syndrome in SCD typically presents with fever, petechial rash, thrombocytopenia, and neurological symptoms in addition to pulmonary findings—a constellation that helps distinguish it from simple vaso-occlusive pulmonary infarction.
Warning
Do not confuse ACS with simple vaso-occlusive pain crisis; ACS requires new pulmonary infiltrate and hypoxemia, making it a distinct and more serious complication.
