Fat macroglobule formation from chylomicrons and non-traumatic fat embolism

A Rare Case of Progressive Encephalopathy in a Sickle Cell Trait Patient: A Case Report

Fat embolism syndrome (FES) is one of the underdiagnosed and underrecognized complications that can happen in multiple medical and surgical conditions. FES can manifest in a broad spectrum of signs and symptoms and affect multiple organ systems in the human body. One of the most commonly involved is the central nervous system (CNS), mainly the brain, which can be involved in different ways, and the presenting symptoms can vary in type and severity. One of the most common causes of FES is trauma, mainly a long bone fracture or any orthopedic injury. However, one of the rare causes of FES is sickle cell disease (SCD) and thalassemia. Generalized and vague presenting symptoms, the rarity of FES, and the absence of well-defined diagnostic criteria make it a challenging diagnosis for healthcare practitioners. FES diagnosis is usually made after having a high index of suspicion in patients with underlying risk factors that can precipitate and contribute to the pathophysiology of FES. Moreover, the diagnosis is usually reached after excluding other more common and treatable conditions.

C-reactive protein interacts with amphotericin B liposomes and its potential clinical consequences

OBJECTIVES

Amphotericin B (AmB) is the gold standard for treating invasive fungal infections. New liposomal-containing AmB formulations have been developed to improve efficacy and tolerability. Serum/plasma C-reactive protein (CRP) values are widely used for monitoring infections and inflammation. CRP shows a high affinity to phosphocholine and it aggregates structures bearing this ligand, e.g. phosphocholine-containing liposomes. Therefore, we studied the interaction between CRP and phosphocholine-containing liposomal AmB preparations in vivo and in vitro.

METHODS

CRP was prepared by affinity chromatography. Liposomal AmB (L-AmB, AmBisome^®) was spiked (final concentrations of L-AmB: 150 mg/L) to CRP-containing serum (final CRP concentration: 300 mg/L). Following the addition of L-AmB, complex formation was monitored turbidimetrically. The size of CRP-L-AmB complexes was assessed using gel filtration. CRP was monitored in patients receiving either L-Amb or AmB lipid complex (ABLC).

RESULTS

Following addition of L-AmB to CRP-containing plasma, turbidimetry showed an increase in absorbance. These results were confirmed by gel permeation chromatography. Similarly, in vivo effects were observed following intravenous administration of AmBisome^®: a decline in CRP values was observed. In patients receiving L-Amb, decline of CRP concentration was faster than in patients receiving ABLC.

CONCLUSIONS

In vitro experiments are suggestive of a complexation between CRP and liposomes in plasma. Interpretation of CRP values following administration of AmBisome^® might be impaired due to this complexation. In vivo formation of complexes between liposomes and CRP might contribute, or even lead, to intravascular microembolisation. Similar effects have been described following the administration of Intralipid^® and other phosphocholine-containing liposomes.

Incidence of Fat Embolism Syndrome in Femur Fractures and Its Associated Risk Factors over Time-A Systematic Review

BACKGROUND

Fat embolism (FE) continues to be mentioned as a substantial complication following acute femur fractures. The aim of this systematic review was to test the hypotheses that the incidence of fat embolism syndrome (FES) has decreased since its description and that specific injury patterns predispose to its development.

MATERIALS AND METHODS

Data Sources: MEDLINE, Embase, PubMed, and Cochrane Central Register of Controlled Trials databases were searched for articles from 1 January 1960 to 31 December 2019.

STUDY SELECTION

Original articles that provide information on the rate of FES, associated femoral injury patterns, and therapeutic and diagnostic recommendations were included.

DATA EXTRACTION

Two authors independently extracted data using a predesigned form.

STATISTICS

Three different periods were separated based on the diagnostic and treatment changes: Group 1: 1 January 1960-12 December 1979, Group 2: 1 January 1980-1 December 1999, and Group 3: 1 January 2000-31 December 2019, chi-square test, χ² test for group comparisons of categorical variables, p-value < 0.05.

RESULTS

Fifteen articles were included (n = 3095 patients). The incidence of FES decreased over time (Group 1: 7.9%, Group 2: 4.8%, and Group 3: 1.7% (p < 0.001)). FES rate according to injury pattern: unilateral high-energy fractures (2.9%) had a significantly lower FES rate than pathological fractures (3.3%) and bilateral high-energy fractures (4.6%) (p < 0.001).

CONCLUSIONS

There has been a significant decrease in the incidence of FES over time. The injury pattern impacts the frequency of FES. The diagnostic and therapeutic approach to FES remains highly heterogenic to this day.

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.

Autopsy diagnosis of fat embolism syndrome

The fat embolism syndrome (FES) is considered a clinical diagnosis. It typically occurs within several days following major traumatic injury, usually involving fractures of the pelvis and/or lower extremities. Fat embolism syndrome is characterized by the onset of respiratory, neurological, cutaneous, and hematologic manifestations and is thought to be related to intravascular embolization of fat, presumably arising from within the fractured bone marrow space. In its most severe form, FES can be lethal. The presence of fat emboli within the microvasculature of the lungs, brain, and sometimes other organs verifies the clinical impression of FES. Despite its relatively well-known clinical characterization, debate exists within the clinical literature regarding the most appropriate diagnostic criteria for FES. Given this fact, along with the fact that FES is a clinical diagnosis, it is not surprising that forensic pathologists may be somewhat reluctant to make a postmortem diagnosis of FES, especially in cases where insufficient clinical information is available. A case of fatal FES is presented in which rapid clinical deterioration occurred, followed by death, such that a clinical diagnosis of FES was never rendered. We propose that, given the correct circumstances, clinical scenario, and autopsy findings, it is appropriate and acceptable to make a postmortem diagnosis of FES. A multitiered approach to the postmortem diagnosis of FES is presented.

Fatal fat embolism syndrome in a case of isolated L1 vertebral fracture-dislocation

Although fat embolism syndrome is a well-known complication of fractures of the long bones or pelvis, fat embolism syndrome occurring subsequent to fracture of the lumbar spine is rare. We report a fatal case of fat embolism syndrome characterized by fat and bone marrow embolism that occurred 36 h after an isolated fracture-dislocation of the L1 vertebra. A postmortem examination was performed and pathological finding demonstrated fat and bone marrow tissue which were disseminated in the bilateral pulmonary arteries. We need to be aware of the possibility of fat embolism syndrome as a complication of spinal fractures, including isolated vertebral body fractures.

Fatal fat embolism in isolated vertebral compression fracture

Fat embolism after long bone and pelvic fractures as well as orthopedic interventions is a well-documented phenomenon, but it is highly unusual after isolated vertebral fractures. We report a case of fatal fat embolism in a 78-year-old man after an isolated vertebral compression fracture with no related orthopedic intervention. A high index of suspicion is necessary for early diagnosis and successfully treating this unusual complication.

Fat embolism

Fat embolism syndrome is a collection of respiratory, haematological, neurological and cutaneous symptoms and signs associated with trauma and other disparate surgical and medical conditions. The incidence of the clinical syndrome is low (< 1% in retrospective reviews) whilst the embolisation of marrow fat appears to be an almost inevitable consequence of long bone fractures. There is debate over the pathogenesis of fat embolism syndrome and it seems a variety of factors interact to produce a spectrum of end organ damage. Many therapeutic interventions and prophylactic strategies have been tried with varying success. Current treatments are supportive and the condition is usually associated with a good outcome. The literature on fat embolism syndrome is extensive and this review aims to discuss the incidence, aetiology, pathophysiology, diagnosis and treatment of fat embolism.

Fatal fat embolism in acute hepatic necrosis with associated fatty liver

We report two cases of generalized nonviolent hepatogenic fat embolism. A 63-year-old woman was sent to the hospital with suspected mushroom poisoning. Shock symptoms occurred quickly and could not be treated effectively; the patient died 24 h after admission. Postmortem examination showed acute yellow dystrophy of the liver with a severe preexisting fatty liver. Any intoxication including Amanita phalloides could be excluded. In all probability, a fulminant viral hepatitis caused liver dystrophy, and the decay of the fatty liver cells led to generalized fat embolism as the cause of death. The second patient, a 46-year-old man, was reported to have suffered from an acute illness while in prison and died after having been transferred to the local hospital. Histological examinations showed an acute liver dystrophy probably caused by fulminant viral hepatitis with fatty degeneration. In this case, the cause of death was also found to be generalized fat embolism.

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.