An autopsy case of non-traumatic fat embolism syndrome

A diagnostic strategy for pulmonary fat embolism based on routine H&E staining using computational pathology

Pulmonary fat embolism (PFE) as a cause of death often occurs in trauma cases such as fractures and soft tissue contusions. Traditional PFE diagnosis relies on subjective methods and special stains like oil red O. This study utilizes computational pathology, combining digital pathology and deep learning algorithms, to precisely quantify fat emboli in whole slide images using conventional hematoxylin-eosin (H&E) staining. The results demonstrate deep learning's ability to identify fat droplet morphology in lung microvessels, achieving an area under the receiver operating characteristic (ROC) curve (AUC) of 0.98. The AI-quantified fat globules generally matched the Falzi scoring system with oil red O staining. The relative quantity of fat emboli against lung area was calculated by the algorithm, determining a diagnostic threshold of 8.275% for fatal PFE. A diagnostic strategy based on this threshold achieved a high AUC of 0.984, similar to manual identification with special stains but surpassing H&E staining. This demonstrates computational pathology's potential as an affordable, rapid, and precise method for fatal PFE diagnosis in forensic practice.

Rare, fatal pulmonary fat embolism after acupuncture therapy: A case report and literature review

BACKGROUND

Death from nontraumatic pulmonary fat embolism associated with minor soft tissue contusion, surgery, cancer chemotherapy, hematologic disorders and so on has been reported. Patients often present with atypical manifestations and rapid deterioration, making diagnosis and treatment difficult. However, there are no reported cases of death from pulmonary fat embolism after acupuncture therapy. This case emphasizes that the stress induced by acupuncture therapy, a mild soft tissue injury, plays an important role in pulmonary fat embolism. In addition, it suggests that in such cases, pulmonary fat embolism as a complication of acupuncture therapy needs to be taken seriously, and autopsy should be used to identify the source of fat emboli.

CASE PRESENTATION

The patient was 72 years old female and experienced dizziness and fatigue after silver-needle acupuncture therapy. She experienced a significant drop in blood pressure and died 2 h later despite treatment and resuscitation. A systemic autopsy and histopathology examination (H&E and Sudan Ⅲ staining) were performed. More than 30 pinholes were observed in the lower back skin. Focal hemorrhages were seen surrounding the pinholes in the subcutaneous fatty tissue. Microscopically, numerous fat emboli were observed in the interstitial pulmonary arteries and alveolar wall capillaries, in addition to the vessels of the heart, liver, spleen and thyroid gland. The lungs showed congestion and edema. The cause of death was identified as pulmonary fat embolism.

CONCLUSION

This article suggests that high vigilance for risk factors and the complication of pulmonary fat embolism following silver-needle acupuncture therapy should be exercised. In postmortem examinations, it should be pay attention that the peripheral arterial system and the venous system draining from non-injured sites should be examined for the formation of fat emboli, which can help distinguish posttraumatic and nontraumatic pulmonary fat embolism.

Nontrombotic Pulmonary Embolism: Different Etiology, Same Significant Consequences

Nontrombotic pulmonary embolism represents the embolization of different types of materials (cells, organisms, gas, foreign material) into pulmonary circulation. The disease is uncommon, and clinical presentation together with laboratory findings are nonspecific. Its pathology is usually misdiagnosed based on imaging findings as pulmonary thromboembolism, but the correct diagnosis is essential because different therapeutic approaches are required. In this context, knowledge of the risk factors associated with nontrombotic pulmonary embolism and specific clinical symptoms is fundamental. Our objective was to discuss the specific features of the most common etiologies of nontrombotic pulmonary embolism, gas, fat, amniotic fluid, sepsis and tumors, to provide assistance for a rapid and correct diagnosis. Because the most common etiologies are iatrogenic, knowledge of the risk factors could be an important tool for prevention or rapid treatment if the disease develops during different procedures. The diagnosis of nontrombotic pulmonary embolisms represent a laborious challenge, and endeavors should be made to prevent development and increase awareness of this disease.

Label-Free Diagnosis of Pulmonary Fat Embolism Using Fourier Transform Infrared (FT-IR) Spectroscopic Imaging

The diagnosis of pulmonary fat embolism (PFE) is of great significance in the field of forensic medicine because it can be considered a major cause of death or a vital reaction. Conventional histological analysis of lung tissue specimens is a widely used method for PFE diagnosis. However, variable and labor-intensive tissue staining procedures impede the validity and informativeness of histological image analysis. To obtain complete information from tissues, a method based on infrared imaging of unlabeled tissue sections was developed to identify pulmonary fat emboli in the present study. We selected 15 PFE-positive lung samples and 15 PFE-negative samples from real cases. Oil red O (ORO) staining and infrared spectral imaging collection were both performed on all lung tissue samples. And the fatty tissue of the abdominal wall and the embolized lipid droplets in the lungs were taken for comparison. The results of the blind, evaluation by pathologists, showed good agreement between the infrared spectral imaging of the lung tissue and the standard histological stained images. Fourier transform infrared (FT-IR) spectroscopic imaging significantly simplifies the typical painstakingly laborious histological staining procedure. And we found a difference between lipid droplets embolized in abdominal wall fat and lung tissue.

Syncope as the initial presentation of pulmonary embolism in two patients with hepatocellular carcinoma: Two case reports and literature review

RATIONALE

Pulmonary embolism (PE) has diverse clinical manifestations and syncope might be the first or only symptom of PE. Tumor disease usually presents with symptoms associated with the primary site, however, PE may be the first manifestation of occult tumors.

PATIENT CONCERNS

Here, we report 2 patients admitted to our hospital because of syncope. One patient had a chronic hepatitis B history of more than 20 years and the other patient had chronic heavy drinking for many years. Neither patient had been diagnosed with neoplastic disease before admission.

DIAGNOSES

Clinical examinations, including laboratory tests and imaging tests upon admission demonstrated PE resulting in syncope. Furthermore, malignant hepatocellular carcinoma (HCC), inferior vena cava, and right atrium tumor thrombus were diagnosed.

INTERVENTIONS

Thrombolysis and anti-coagulation therapy were performed immediately after the diagnosis of PE. Twenty-seven HCC patients with PE in 27 articles from 1962 to 2020 in the PubMed database were reviewed.

OUTCOMES

The improvement was achieved that no syncope recurred after treatment of PE. The oxygen partial pressure increased and the D-dimer level decreased. The clinical characteristics of 27 HCC patients with PE were summarized and analyzed.

LESSONS

It is important for clinicians to be aware that occult carcinoma might be a reason for patients with PE presenting with syncope. If PE cannot be explained by common causes, such as our patient, and HCC should be highly suspected when inferior vena cava and right atrial mass are found on imaging tests.

Cerebral fat embolism after traumatic bone fractures: a structured literature review and analysis of published case reports

Background

The incidence of cerebral fat embolism (CFE) ranges from 0.9–11%, with a mean mortality rate of around 10%. Although no univocal explanation has been identified for the resulting fat embolism syndrome (FES), two hypotheses are widely thought: the ‘mechanical theory’, and the ‘chemical theory’. The present article provides a systematic review of published case reports of FES following a bone fracture.

Methods

We searched MEDLINE, Web of Science and Scopus to find any article related to FES. Inclusion criteria were: trauma patients; age ≥ 18 years; and the clinical diagnosis of CFE or FES. Studies were excluded if the bone fracture site was not specified.

Results

One hundred and seventy studies were included (268 cases). The male gender was most prominent (81.6% vs. 18.4%). The average age was 33 years (±18). The mean age for males (29 ± 14) was significantly lower than for females (51 ± 26) (p < 0.001). The femur was the most common fracture site (71% of cases). PFO was found in 12% of all cases. Univariate and multivariate regression analyses showed the male gender to be a risk factor for FES: RR 1.87 and 1.41, respectively (95%CI 1.27–2.48, p < 0.001; 95%CI 0.48–2.34, p < 0.001).

Conclusions

FES is most frequent in young men in the third decades of life following multiple leg fractures. FES may be more frequent after a burst fracture. The presence of PFO may be responsible for the acute presentation of cerebral embolisms, whereas FES is mostly delayed by 48–72 h.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13049-021-00861-x.

Post-traumatic cerebral fat embolism syndrome with a favourable outcome: a case report

Background

Fat embolism syndrome (FES) is a change in physiology resulting from mechanical causes, trauma, or sepsis. Neurological manifestations of FES can vary from mild cognitive changes to coma and even cerebral oedema and brain death. Here, we present an unusual case of cerebral fat emboli that occurred in the absence of acute chest syndrome or right-to-left shunt.

Case presentation

A previously healthy 57-year-old right-handed male was admitted to our department because of unconsciousness after a car accident for 3 days. He suffered from multiple fractures of the bilateral lower extremities and pelvis. This patient had severe anaemia and thrombocytopenia. Head MRI showed multiple small lesions in the whole brain consistent with a “star field” pattern, including high signals on T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images in the bilateral centrum semiovale; both frontal, parietal and occipital lobes; and brainstem, cerebellar hemisphere, and deep and subcortical white matter. Intravenous methylprednisolone, heparin, mannitol, antibiotics and nutritional support were used. Although this patient had severe symptoms at first, the outcome was favourable.

Conclusions

When patients have long bone and pelvic fractures, multiple bone fractures and deteriorated neurological status, cerebral fat embolism (CFE) should be considered. Additionally, CFE may occur without an intracardiac shunt. The early diagnosis and appropriate management of FES are important, and prior to and following surgery, patients should be monitored comprehensively in the intensive care unit. With appropriate treatment, CFE patients may achieve good results.

Nontraumatic Multiple-Organ Fat Embolism: An Autopsy Case and Review of Literature

The patient was an 88-year-old woman with a 10-year history of hypertension. She was suspected to have been hit by a car. At the time of the event, she was conscious and able to stand on her own and had no obvious injuries. She was sent home, but she lapsed into unconsciousness and was nonresponsive after 2 hours. She was sent to the hospital, and her heartbeat and breathing stopped. After half an hour of rescue attempts, her heartbeat did not recover, and she was declared dead. During the autopsy, a small subcutaneous hemorrhage was observed below the right knee joint. No obvious internal organ injuries or bone fractures were observed. The deceased also had mild atherosclerosis in the coronary arteries and an old cerebral infarction in the right cerebellum. The tissue histopathological tests showed distinct fat embolism in multiple organs, including the brain, lungs, kidneys, liver, and pancreas. A postmortem blood biochemistry test of the heart blood showed that the levels of low-density lipoprotein, cholesterol, triglycerides, and free fatty acids in the blood were increased, and the level of C-reactive protein was elevated. According to the autopsy results, the direct cause of death was multiorgan fat embolism. This case suggests that aging, hypertension, and hyperlipidemia may be risk factors for nontraumatic fat embolism under stressful conditions.

Posttraumatic subarachnoid fat embolism: Case presentation and literature review

Fat embolism in the subarachnoid space has a unique pathophysiology and clinical picture when compared to fat embolism syndrome. Lipid deposits in the subarachnoid space-most commonly the sequela of dermoid rupture in the neuraxis-can cause an inflammatory reaction leading to irritation of nearby neurovascular structures. Herein, we report the only case in the United States, to our knowledge, of a patient diagnosed with subarachnoid fat emboli secondary to sacral fracture who initially presented with a normal head CT and subsequently developed visual changes.

Unusual clinicopathological presentation of nontraumatic cerebral fat embolism: Two-case report

RATIONALE

Fat embolism syndrome (FES) is characterized by the classical triad of cerebral, respiratory, and cutaneous manifestations. In contrast, cerebral fat embolism (CFE), corresponding to incomplete pure type FES, is much rarer and usually follows trauma. CFE typically shows a "starfield" pattern on diffusion-weighted magnetic resonance imaging due to the involvement of multiple small arteries. We report 2 unusual cases of CFE that showed a nontraumatic etiology and the involvement of a single dominant cerebral artery.

PATIENT CONCERNS

Case 1 was a 33-year-old woman without a history of trauma who visited the emergency room due to hemiparesis and hemisensory deficits. She was a heavy smoker and had used oral contraceptives for several years. Most importantly, she had 2 experiences of autologous fat grafting 2 months previously. Magnetic resonance angiography (MRA) revealed acute occlusion of the right middle cerebral artery. Case 2 was an 80-year-old man suddenly presented with dizziness, ataxia, and left-sided sensorimotor dysfunction. He had a history of hypertension, untreated atrial fibrillation, and chronic alcoholism. MRA demonstrated the occlusion of the distal basilar artery.

DIAGNOSIS

Case 1: Microscopic findings demonstrated variable sized fat vacuoles intermixed with moderate amounts of thrombi. Case 2: Histologically, mature adipocytes were intermingled with fibrin, blood cells, and a fragment of entrapped soft tissue resembling the vessel wall.

INTERVENTION

Case 1 and 2 underwent aspirational thrombectomy guided by transfemoral cerebral angiography.

OUTCOME

Case 1 recovered well but Case 2 still suffers from gait ataxia.

LESSONS

CFE can rarely occur in various nontraumatic conditions, with or without evident etiology. Furthermore, it may not show characteristic clinicopathological manifestations. Therefore, careful follow up of those who have undergone procedures that are likely to trigger FES or who have hemodynamic or hypercoagulable risk factors is needed.

Approaching pulmonary fat embolism on postmortem computed tomography

PURPOSE

Pulmonary fat embolism (PFE) is a relevant diagnosis playing a role as a sign of vitality or a cause of death. Its severity is assessed according to histological grading systems like that of Falzi. The aim of this study was to determine the utility of unenhanced postmortem computed tomography (PMCT) for PFE diagnosis based on the detection of fat layers.

METHODS

Consecutive cases with PMCT and autopsy were studied retrospectively. The case group consisted of cases with positive PFE, and the control group included cases with negative PFE. Three observers independently assessed PMCT data for fat layers in the pulmonary trunk and the right and left pulmonary artery. For cases with fat layers, autopsy protocols were assessed for the cause of death, relation to trauma, and undertaken resuscitation measures.

RESULTS

Eight hundred thirty cases were included: 366 PFE positive cases (144 of Falzi grade 1, 63 of 1.5, 99 of 2, 28 of 2.5, and 32 of 3) and 464 PFE negative cases. Interrater reliabilities varied between substantial and almost perfect, and discrepancies were solved according to majority. Eighteen cases showed fat layers on PMCT (2 controls-traumatic instantaneous deaths-, 16 PFE positive cases). PMCT showed low sensitivity but high specificity for PFE diagnosis. The layers were located at the same position in the pulmonary trunk directly adjacent to the pulmonary valve distal to the right ventricle.

CONCLUSION

Fat layer on PMCT is a rare finding but relates to PFE diagnosis, especially of severe histological grade. It is to be expected in a typical position within the pulmonary trunk.