Causes of the acute chest syndrome:
(1) infection (pneumonia)
(1a) Chlamydia pneumoniae
(1b) Mycoplasma pneumoniae
(1c) bacteria (Streptococcus pneumoniae, Hemophilus influenzae, gram negative enterics, Staphylococcus species, beta hemolytic Streptococcus, Legionella pneumophila, mycobacteria)
(1d) viral (RSV, influenza, parainfluenza, HSV, adenovirus, parvovirus, rhinovirus, others)
(1e) multiple pathogens
(2) embolism, including fat embolism
(3) infarction secondary to thrombosis or embolism
(4) mixed (infection of infarcted area, infarction of pneumonia)
(5) pulmonary hemorrhage
(6) vaso-occlusion due to sickling of red cells in the pulmonary vasculature
If the syndrome is due to an infectious agent, then cultures or serological tests may be positive.
If the cause is a bacterial pneumonia and appropriate antibiotics are started, then the course is usually benign with regression of the infiltrate and clinical improvement.
