Positron emission tomography-positive squalene-induced lipoid pneumonia confirmed by gas chromatography-mass spectrometry of bronchoalveolar lavage fluid

The Quantitation of Squalene and Squalane in Bronchoalveolar Lavage Fluid Using Gas Chromatography Mass Spectrometry

Chemicals of unknown inhalational toxicity are present in electronic cigarette and vaping products. E-cigarettes typically contain nicotine and other relatively hydrophilic chemicals while vaping products typically contain cannabinoids and other hydrophobic chemicals. For example, vaping products can include hydrophobic terpenes such as squalane (SQA) and squalene (SQE). However, little is known about the SQA and SQE transmission from liquid to aerosol. SQA and SQE are used in commercial products that are applied dermally and ingested orally, but limited information is available on their inhalational exposure and toxicity. We developed and validated a quantitative method to measure SQE and SQA in bronchoalveolar lavage fluid to assess if these chemicals accumulate in lung epithelial lining fluid after inhalation. Calibration curves spanned a range of 0.50–30.0 µg analyte per mL bronchoalveolar lavage fluid. Recoveries were found to be 97–105% for SQE and 81–106% for SQA. Limits of detection were 0.50 μg/ml for both SQE and SQA. The method was applied to bronchoalveolar lavage fluid samples of patients from the 2019 outbreak of e-cigarette, or vaping, product use-associated lung injury (EVALI) and a comparison group. Neither SQA nor SQE was detected above the method LOD for any samples analyzed; conversely, SQA or SQE were reproducibly measured in spiked quality control BAL fluids (relative standards deviations <15% for both analytes). Further applications of this method may help to evaluate the potential toxicity of SQA and SQE chronically inhaled from EVPs.

A gas chromatography-mass spectrometry method for quantifying squalane and squalene in aerosol emissions of electronic cigarette, or vaping, products

Numerous chemicals of unknown inhalational toxicity have been measured in electronic cigarette, or vaping, products (EVPs). In addition, little is known about the liquid-to-aerosol transmission and deliveries of these chemicals, including oil-like terpenes such as squalene (SQE) and squalane (SQA). To provide information on the aerosol deliveries of these compounds from EVPs, we developed and validated a quantitative method to measure squalene and squalane in EVP aerosol emissions. Validation parameters include measurement repeatability (SQA and SQE %RSD <6%), intermediate precision (SQA: %RSD 11%, SQE: %RSD 17%), accuracy (SQA: 86-107%, SQE: 104-113%), matrix effects, method robustness, and analyte stability. Limits of detection were 6.06 ng/mL puffed air volume for both squalene and squalane. The method was used to measure squalene and squalane in aerosol emissions of 153 EVPs associated with case patients from a recent outbreak of e-cigarette, or vaping, product use associated lung injury (EVALI). The EVPs analyzed were organized into nicotine, cannabidiol, and tetrahydrocannabinol products by the percentage of nicotine, cannabidiol, and tetrahydrocannabinol in total particulate matter after vaping. In case-associated tetrahydrocannabinol products the detection rates and mean concentrations were 82.4% and 33.0 ng/mL puffed air for squalene and 4.41% and 7.80 ng/mL puffed air for squalane.

Pattern of FDG-PET uptake in lipoid pneumonia simulating lung cancer

Lipoid pneumonia presents with a variety of lung abnormalities, particularly mass forming lesions that mimic lung cancers. While ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) is expected to discriminate both diseases, some previous reports showed pseudo-positive FDG uptake in lipoid pneumonia. Here, we report a case of pathologically proven chronic lipoid pneumonia in a 78-year-old Japanese man. Computed tomography (CT) showed multi-lobar mass-forming lesions with a fat-density. PET confirmed the spotty accumulation of FDG in the corresponding fat-density area on CT, suggesting lipoid pneumonia. We reviewed the literature and discussed the FDG uptake patterns in lipoid pneumonia.