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Fat embolism is the next common form
after thromboembolism.
More than 90 % cases occur after fracture
of long bones or, rarely due to trauma to the fatty area and extensive
burn involving subcutaneous fat.
Pathogenesis:
There is mechanical obstruction to the
pulmonary vessels by micro-emboli of neutral fat producing local
accumulation of platelets and red blood cells with liberation of free
fatty acids.
Free fatty acids cause toxic injury to
endothelium, activation of platelets and recruitment of granulocytes
(free radicals, proteases, and eicosanoids).
Clinical presentation:
Clinically
(fat embolism syndrome), there is sudden pulmonary
insufficiency beginning 1 to 3 days after injury.
Most of the patients develop a diffuse petechial rash and
some may have neurological symptoms (irritability and restlessness).
This is followed by delirium and coma.
Thrombocytopenia and anemia may also occur.
These are fatal up to 10% cases.
Diagnosis:
Fat stain of
frozen section reveals micro-vascular fat globules.
Microscopically, edema and hemorrhage and
hyaline membrane in lungs may be seen.

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