Oil red O staining for lipid-laden macrophage index of bronchoalveolar lavage: interobserver agreement and challenges to interpretation

Interobserver agreement and diagnostic challenges of Congo red staining for amyloid detection on fat pad aspiration biopsies

INTRODUCTION

Congo red staining of fat pad fine needle aspiration specimens is a method utilized for evaluation of amyloid deposition. However, these specimens can pose diagnostic challenges for cytopathologists. As part of ongoing internal quality improvement measures, the objective of this study was to evaluate the intradepartmental interobserver agreement of these specimens and to identify factors that affect the variability of the interpretations.

MATERIALS AND METHODS

There were 7 participants, which included 3 trainees, 3 cytopathologists, and 1 cytotechnologist. Each participant reviewed 50 Congo red stained fat pad fine needle aspiration slides. The interpretations were categorized into 3 groups: negative, indeterminate/suspicious, and positive. The participants also noted any interpretation challenges they encountered for each case.

RESULTS

There was only slight interobserver agreement among all participants (κ = 0.133). Stratified by participant group, the interobserver agreement among the trainees was slight bordering on poor (κ = 0.028) and among cytopathologists was fair (κ = 0.249). The highest agreement between 2 observers was between 2 cytopathologists and the level of agreement was moderate bordering on fair (κ = 0.426). There were only 3 cases (6.0%) with full agreement among observers, while in 25 cases (50.0%), there were 2 category differences in interpretations. The primary diagnostic challenge reported by participants was when weak or focal birefringence was encountered as well as cases complicated by poor stain quality and overstaining.

CONCLUSIONS

We found only slight interobserver agreement among all study participants. A major area of challenge was cases with weak birefringence resulting in high variance of interpretation among participants.

Physiological response to fetal intravenous lipid emulsion

In preterm neonates unable to obtain sufficient oral nutrition, intravenous lipid emulsion is life-saving. The contribution of post-conceptional level of maturation to pathology that some neonates experience is difficult to untangle from the global pathophysiology of premature birth. In the present study, we determined fetal physiological responses to intravenous lipid emulsion. Fetal sheep were given intravenous Intralipid 20® (n = 4 females, 7 males) or Lactated Ringer's Solution (n = 7 females, 4 males) between 125 ± 1 and 133 ± 1 d of gestation (term = 147 d). Manufacturer's recommendation for premature human infants was followed: 0.5-1 g/kg/d initial rate, increased by 0.5-1 to 3 g/kg/d. Hemodynamic parameters and arterial blood chemistry were measured, and organs were studied postmortem. Red blood cell lipidomics were analyzed by LC-MS. Intravenous Intralipid did not alter hemodynamic or most blood parameters. Compared with controls, Intralipid infusion increased final day plasma protein (P=0.004; 3.5 ± 0.3 vs. 3.9 ± 0.2 g/dL), albumin (P = 0.031; 2.2 ± 0.1 vs. 2.4 ± 0.2 g/dL), and bilirubin (P<0.001; conjugated: 0.2 ± 0.1 vs. 0.6 ± 0.2 mg/dL; unconjugated: 0.2 ± 0.1 vs. 1.1 ± 0.4 mg/dL). Circulating IGF-1 decreased following Intralipid infusion (P<0.001; 66 ± 24 vs. 46 ± 24 ng/mL). Compared with control Oil Red O liver stains (median score 0), Intralipid-infused fetuses scored 108 (P=0.0009). Lipidomic analysis revealed uptake and processing of infused lipids into red blood cells, increasing abundance of saturated fatty acids. The near-term fetal sheep tolerates intravenous lipid emulsion well, although lipid accumulates in the liver. Increased levels of unconjugated bilirubin may reflect increased red blood cell turnover or impaired placental clearance. Whether Intralipid is less well tolerated earlier in gestation remains to be determined.

Lipid‐Laden Macrophage Index as a Diagnostic Tool for Pediatric Aspiration: A Systematic Review

Objective

Lipid-laden macrophage index (LLMI) has been proposed as a marker for aspiration on bronchoalveolar lavage. It has also been studied as a marker for gastroesophageal reflux and other pulmonary diseases. This review aims to determine the clinical correlation between LLMI and pediatric aspiration.

Data Sources

PubMed (MeSH search), Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) portals through December 17th, 2020.

Review Methods

Preferred Reporting Items for Systematic Review and Meta-Analysis criteria were followed, and a quality assessment of included studies was performed using the Methodological Index for Non-Randomized Studies. Search criteria included all occurrences in the title or abstract of the terms "pulmonary aspiration" and "alveolar macrophages."

Results

Five studies describing 720 patients met inclusion, 3 retrospective case-control studies, and 2 prospective observational studies. Four studies suggested a link between elevated LLMI and aspiration, and 1 found no association. Control groups varied and included healthy nonaspirators to nonaspirators with other pulmonary diseases. Diagnosis of aspiration was not standardized across the studies. Three papers proposed cutoff values for LLMI, all different.

Conclusion

The existing literature indicates that LLMI is not a sensitive or specific marker for aspiration. Further study is needed to define the utility of LLMI in pediatric aspiration.

Utilization of Oil Red O staining for assessing aspiration risk in lung transplant patients: A multidisciplinary prospective study with clinical practice insights

BACKGROUND

Gastroesophageal reflux disease with microaspiration has been associated with graft dysfunction in lung transplant patients. Identifying patients with aspiration is clinically important because it enables implementation of appropriate interventions like antireflux therapy. Oil Red O (ORO) staining with determination of the lipid-laden macrophage index (LLMI) has been proposed as a noninvasive surrogate marker in the detection of aspiration. The aim of this study was to prospectively evaluate clinical utilization of ORO staining in the assessment of aspiration risk.

METHODS

All transbronchial surgical pathology biopsies obtained in lung transplant patients undergoing routine surveillance from August 2020 through November 2021 were included in this study. Clinical team members prospectively ascertained the aspiration risk category (ARC) of each patient both before and after biopsy findings and recorded reasons for change in ARC.

RESULTS

A total of 132 transbronchial biopsies with concurrent LLMI were included in the study. LLMI was low in 51 cases (38.6%), including 21 of the 54 cases (38.9%) where aspiration was suggested based on the transbronchial biopsy findings. In total, 19 cases (14.4%) underwent a change in ARC post-biopsy including 10 that were upgraded and nine cases that were downgraded. Transbronchial biopsy findings were noted as the reason for change in ARC in the majority (15/19; 79%) of cases; only a minority (2/19; 10.5%) were due to the LLMI. Notably, 16 cases (12.1%) had a low LLMI with high-risk post-biopsy ARC and nine cases (6.8%) had a high LLMI with low-risk post-biopsy ARC.

CONCLUSIONS

This study observed that clinical evaluation for aspiration relied more heavily on transbronchial biopsy findings. Although LLMI may retain clinical utility in some scenarios, reevaluation of the clinical value of ORO testing would be prudent.

Oil Red O Staining of Pulmonary Macrophages in Bronchoalveolar Lavage Specimens Is Not Specific for Vaping-Associated Lung Injury

Objectives

Oil Red O (ORO) positivity in bronchoalveolar lavage (BAL) fluid macrophages in the setting of e-cigarette, or vaping, product use–associated acute lung injury (EVALI) has been frequently requested by clinicians based on rare reports and subsequent US Centers for Disease Control and Prevention guidelines. The aim of this study was to determine the specificity of ORO staining in BAL specimens with disease states other than EVALI.

Methods

Consecutive BAL specimens (October-December 2019) were stained with ORO. The lipid-laden macrophage index (LLMI) was calculated for each case.

Results

We studied BAL samples from 50 patients. Indications for BAL were surveillance bronchoscopy for lung transplantation (27/50), suspected infection (12/50), sarcoidosis/suspected sarcoidosis (3/50), nodules or ground-glass opacities (3/50), hemoptysis (2/50), asthma or eosinophilic pneumonia (2/50), and idiopathic pulmonary fibrosis (1/50). ORO staining was seen in BAL fluid macrophages in 45 of 50 cases (focal in 18, moderate in 23, diffuse in 4); LLMI ranged from 0 to 218. Using a threshold of LLMI of 85 or higher as positive, ORO was positive in 7 of 50 (14%) cases (range, 85-218).

Conclusions

ORO staining in BAL fluid macrophages is not specific for EVALI. Even when an LLMI of 85 or higher is used as a threshold for positivity, ORO positivity occurs in a significant subset of non–vaping-related cases.

Correlation between cytology Oil Red O staining and lung biopsy specimens: utility of the lipid-laden macrophage index

INTRODUCTION

Oil Red O staining is used for enumeration of the lipid-laden macrophage index (LLMI) as a surrogate for aspiration. As part of quality improvement efforts aimed at optimizing resource utilization, the utility of this stain in current cytopathology practice was re-evaluated. The objective of this study was to explore the clinical utility of Oil Red O staining in bronchoalveolar lavage (BAL) samples by correlating the LLMI with findings in concurrent histologic tissue samples.

MATERIALS AND METHODS

Lung transbronchial biopsy specimens that suggested aspiration that were submitted with concurrent BAL cytology samples were retrieved. Lung tissue biopsies were reviewed for the presence of foamy alveolar macrophages (graded as 0, 1+, and 2+), foreign material, and giant cells. The concurrent BAL was reviewed with consensus determination of the LLMI.

RESULTS

A total of 53 cases were identified. On histology, 13 cases (24.5%) were found to have no foamy alveolar macrophages, 23 cases (43.4%) were found to have 1+ foamy alveolar macrophages, and 17 cases (32.1%) were found to have 2+ foamy alveolar macrophages. Six cases (11.3%) were found to have foreign material, and 10 cases (18.9%) were found to have multinucleated giant cells. The average LLMI score was 16, with 44 (83.0%) in the low range (LLMI &lt;40) and 9 (17.0%) in the intermediate range (LLMI of 40-90).

CONCLUSIONS

None of the cases in our study had an LLMI that exceeded the cutoff value for which aspiration would be suspected. We found no correlation of the LLMI with lung biopsies that suggested aspiration.

Effects of testosterone on skin structure and factors related to androgen conversion and binding in Hetian sheep

The effects of androgens on human skin mainly include the regulation of growth and differentiation of hair follicles and sebaceous glands. Androgens may have some physiological roles in sheep skin that are similar to those of humans, but further confirmation is needed. Therefore, Hetian sheep were chosen in this study as an animal model to explore the effects of testosterone on skin structure and factors related to androgen conversion and binding in Hetian sheep. The sheep were treated with different concentrations of testosterone for 42 days. Skin tissue sections were prepared and then subjected to hematoxylin-eosin, Sacpic, Masson's trichrome, and Oil Red O staining to observe changes in skin morphology. Changes in the content of blood-related factors were also detected using ELISA kits. The skin tissue distribution of androgen receptor was explored by immunohistochemistry and immunofluorescence assays. The results showed that testosterone significantly increases the sebaceous gland area and stimulates the formation of new sebaceous glands. Further exploration revealed that testosterone promotes the proliferation of sebaceous gland juvenile cells. However, testosterone was found to have no significant effect on hair follicle density and hair follicle structure. Testosterone increased dihydrotestosterone levels but decreased 5α-reductase 1 and 5α-reductase 2 levels. The androgen receptors were distributed in the hair follicles, sebaceous glands, and some major skin appendages of Hetian sheep. This study suggests that androgens can be effective in regulating sebum production in sheep. This study will help advance research efforts to further explore the molecular and cellular mechanisms by which androgens modify sheep follicles and sebaceous glands.

Bronchoalveolar Lavage in a Pediatric Population

OBJECTIVES

The cytomorphologic findings of bronchoalveolar lavage (BAL) in pediatrics were correlated with clinical symptoms.

METHODS

Patient demographics, clinical symptoms/history, cytomorphologic findings, and oil red O (ORO) staining of 100 pediatric patients who underwent BAL between 2014 and 2016 were reviewed at a large academic institution.

RESULTS

Of the 100 patients (males/females, 62:38), the most common conditions for BAL included cough (46/100), reflux (39/100), pneumonia (30/100), dysphagia (22/100), asthma (19/100), and cystic fibrosis (15/100). Sixteen of 100 patients were admitted with pulmonary symptoms from the emergency department. Cytomorphologic findings showed acute inflammation in 37 BALs and chronic inflammation in 9. Abundant thick mucin was present in 3 cytology cases from patients with cystic fibrosis. Fungal elements were detected in 3 cases (Candida, Aspergillus, and Pneumocystis jirovecii) and viral effects (rhinovirus) in one. Thirty-seven of 100 had rare ORO-positive lipid-laden macrophages (LLMs), 7 of 100 had moderate LLMs, 11 of 100 had numerous LLMs, 18 of 100 had positive staining without the degree of staining, 25 of 100 had negative ORO staining, and 2 of 100 had noncontributory ORO staining. An iron stain was done on 15 BALs (2 positive, 9 negative, and 4 noncontributory).

CONCLUSIONS

BAL cytology is a useful tool in pediatrics to discriminate underlying causes of aerodigestive system conditions, while ORO staining may occasionally help.

Multi-Omics Analysis of Mammary Metabolic Changes in Dairy Cows Exposed to Hypoxia

Hypoxia exposure can cause a series of physiological and biochemical reactions in the organism and cells. Our previous studies found the milk fat rate increased significantly in hypoxic dairy cows, however, its specific metabolic mechanism is unclear. In this experiment, we explored and verified the mechanism of hypoxia adaptation based on the apparent and omics results of animal experiments and in vitro cell model. The results revealed that hypoxia exposure was associated with the elevation of AGPAT2-mediated glycerophospholipid metabolism. These intracellular metabolic disorders consequently led to the lipid disorders associated with apoptosis. Our findings update the existing understanding of increased adaptability of dairy cows exposure to hypoxia at the metabolic level.