Fat particles in plasma. The macroglobule: its relevance to the concept of fat embolism

Lipid Embolism in Obese Göttingen Minipigs

Pigs are used as a model of human obesity, both for metabolic characterization and for evaluation of pharmacological interventions. Over a period of 7 years, acute death or clinical signs requiring immediate euthanasia were observed in 12 obese Göttingen minipigs (GMs) included in different pharmacological studies. The GM were fed ad libitum on normal chow-diet and the unscheduled deaths occurred in animals treated with drug candidates as well as in untreated animals. The most prominent clinical signs requiring euthanasia included varying degrees of respiratory distress; and on histopathological examination, thickening of the alveolar septa due to vacuolation was observed throughout the lung in 10 of the 12 animals. Furthermore, vacuolation in glomeruli of the kidney was detected in 9 of the 10 animals. Oil red O staining of cryosections demonstrated that the vacuoles both in lung and kidney contained lipid, and immunohistochemistry with anti-von Willebrand factor and transmission electron microscopy revealed that the lipid was localized in the lumen of blood vessels establishing the occurrence of fatal pulmonary lipid embolism. Additionally, lipogranulomatous inflammation in the abdominal adipose tissue was observed in all the GMs with lipid emboli.

The pathogenesis of fat embolism

Fat embolism is a common autopsy finding in patients with or without a history of trauma. There are two basic mechanisms causing fat to embolize. Depot-derived fat embolism arises by disruption of depot fat, usually as a result of trauma, allowing direct entry into the bloodstream. Plasma-derived fat embolism is caused by agglutination of endogenous or infused exogenous fat such as Intralipid, with consequent embolism. Chylomicrons and Intralipid liposomes are known to undergo calcium-dependent agglutination by C-reactive protein (CRP), and this may play a role in vivo in this type of fat embolism.

Mucin embolism to cerebral arteries: a fatal complication of carcinoma of the breast

The case is reported of a woman with a mucin producing lobular carcinoma of the breast with metastases to many bone sites, whose terminal neurological illness was the result, not of cerebral metastases, but of cerebral infarcts. These were caused by emboli of mucin and emulsified fat, originating in bone metastases. The pathogenesis of this embolism is compared with that of traumatic fat embolism. Attention is drawn to this process because emboli of this type have never been reported and because this distant nonmetastatic effect of carcinoma may have been overlooked in other cases. It is suggested that this mechanism should be considered in the diagnosis of otherwise obscure cerebral infarction.