Significance of Oil-Red-O positive macrophages in bronchoalveolar lavage in diagnosing E-cigarettes or vaping product use-associated lung injury: A case series.

Shuang Niu, Glorimar Rivera Colon, Kyle Molberg, Hao Chen, Kelley Carrick, Shirley Yan, Venetia Sarode, Elena Lucas

Diagnostic cytopathology 2021 Jul

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Lipid-laden macrophages detected by Oil-Red-O (ORO) stain in fresh bronchoalveolar lavage (BAL) specimens have been proposed as a potential diagnostic marker for E-cigarettes or vaping product use-associated lung injury (EVALI). However, studies are few, and the sensitivity and specificity of the test have not been thoroughly investigated. We performed ORO stain on fresh BAL specimens from six confirmed EVALI and 36 non-EVALI patients. After semi-quantitative analysis, the sensitivity and specificity of ORO-positive macrophages (OPM) for detection of EVALI were calculated. No significant difference in cytomorphology or raw macrophage count was observed between EVALI and non-EVALI groups (49% vs 55% of all nucleated cells). However, with ORO stain, all EVALI specimens (6/6) showed a high percentage (≥50% of all macrophages) of OPM (mean 87%), and large (≥25% of host macrophage nuclear size) lipid droplets (mean 42%), while the majority of non-EVALI specimens showed a low percentage of OPM (32/36, mean 10%), and small lipid droplets (34/36, mean 6%). The differences between the two groups in both high OPM and large lipid droplet rates are statistically significant (P < .0001 for both comparisons). The combined sensitivity and specificity of high OPM and large lipid droplets for diagnosing EVALI were 100% and 94%, respectively. In BAL specimens obtained from patients with clinically suspected EVALI, a high percentage of OPM with large lipid droplets showed high sensitivity and specificity for the diagnosis of EVALI and may serve as a potentially useful tool in the evaluation of vaping-related lung injury, improving diagnostic accuracy. © 2021 Wiley Periodicals LLC.

Citation

Shuang Niu, Glorimar Rivera Colon, Kyle Molberg, Hao Chen, Kelley Carrick, Shirley Yan, Venetia Sarode, Elena Lucas. Significance of Oil-Red-O positive macrophages in bronchoalveolar lavage in diagnosing E-cigarettes or vaping product use-associated lung injury: A case series. Diagnostic cytopathology. 2021 Jul;49(7):876-884