E-Cigarette or Vaping Product Use-associated Lung Injury: a Review for Pathologists

Introduction:
This article provides an overview of vaping, its associated lung injury, and the role of pathology in its diagnosis. The text discusses the definition, components, and trends of vaping, as well as the clinical and laboratory findings, imaging features, and treatment of electronic cigarette, or vaping, product use-associated lung injury (EVaLI). The pathologic findings and bronchoalveolar lavage (BaL) fluid findings are also discussed. The key points and main message of the article are as follows:

Key Points:

* Vaping is the inhalation of heated aerosol from a small battery-powered device that delivers nicotine or other substances.
* EVaLI is a recent outbreak of severe respiratory illness primarily in the United States that has been linked to vaping products containing tetrahydrocannabinol (ThC) or other cannabinoids.
* Lung biopsies show a spectrum of nonspecific acute lung injury patterns, including organizing pneumonia, diffuse alveolar damage, acute fibrinous and organizing pneumonia, or combinations of the above, accompanied by prominent, foamy macrophage accumulation.
* Lipid-laden macrophages can be identified in BaL fluid in most patients, but their clinical utility remains unclear.
* Classic histologic features of exogenous lipoid pneumonia have not been identified in tissue samples.
* EVaLI is a diagnosis of exclusion that requires clinicopathologic correlation.

Main Message:
The main message of the article is that most cases of vaping-associated lung injury have been linked to vaping products containing ThC or other cannabinoids. The pathologic findings of EVaLI are nonspecific and include a spectrum of acute lung injury patterns accompanied by prominent, foamy macrophage accumulation. Lipid-laden macrophages can be identified in BaL fluid in most patients, but their clinical utility remains unclear. Classic histologic features of exogenous lipoid pneumonia have not been identified in tissue samples. EVaLI is a diagnosis of exclusion that requires clinicopathologic correlation. The article emphasizes the importance of recognizing the potential risks of vaping and the role of pathology in its diagnosis.

Cecchini, Matthew J., Sanjay Mukhopadhyay, andrea V. arrossi, Mary B. Beasley, Yasmeen M. Butt, Kirk D. Jones, Stefan Pambuccian, et al. “E-Cigarette or Vaping Product Use-associated Lung Injury: a Review for Pathologists.” archives of Pathology & Laboratory Medicine 144, no. 12 (December 1, 2020): 1490–1500. https://doi.org/10.5858/arpa.2020-0024-Ra.