Vaping-related lung injury

Abstract

The use of electronic nicotine delivery systems has increased in popularity dramatically over the past decade. Although lung diseases caused by vaping have been reported since the modern invention of the electronic cigarette, in the summer of 2019, patients began to present to health care centers at epidemic levels with an acute respiratory illness relating to vaping, which the Center for Disease Control termed E-cigarette or vaping product use-associated lung injury (EVALI). This review discusses electronic nicotine delivery systems as well as the etiology, clinical presentation, imaging findings, pathologic features, treatment, and long-term consequences of EVALI. We conclude with the practical impact EVALI has had on the practice of pathology.

Keywords: E-cigarette or vaping product use-associated lung injury; Electronic nicotine delivery systems; Pathology; Vaping.

Fig. 1

a–c Coronal enhanced CT images through the anterior a and posterior b lungs show multifocal ground-glass opacity in the bilateral anterior upper lobes; note conspicuous subpleural sparing (arrowheads) affecting the peripheral right lower and medial left basal lung. The posterior lungs b show more pronounced consolidation with developing organization, evidenced by the mild architectural distortion and the band-like nature of the consolidation (arrows) distributed along the bronchi. Coronal maximum intensity projected unenhanced computed tomography c in a different EVALI patient shows diffusely distributed, small, centrilobular ground-glass opacity nodules (arrowheads) typical of a non-fibrotic hypersensitivity pneumonitis pattern

Fig. 2

a, b Bronchoalveolar lavage (BAL) specimens in electronic cigarette or vaping-associated lung injury. BAL specimens are often quite cellular a, mostly inflammatory in nature and contain numerous macrophages. A subset of the macrophages show distended cytoplasm with numerous fine vacuoles (arrow), Papanicolaou stain stain, × 600. While Oil red-O staining is not a useful diagnostic stain, it does highlight the cytoplasmic lipid vacuoles b to be bright red, Oil red-O, × 600

Fig. 3

a–c The major pathologic acute lung injury patterns seen in the setting of electronic cigarette or vaping-associated lung injury. Hyaline membranes of diffuse alveolar damage a with significant background interstitial edema, H&E, × 200. Acute fibrinous and organizing pneumonia characterized by the deposition of abundant fibrin in airspaces b, exceeding the number of polyps of organizing pneumonia, H&E, × 100. A polyp of immature fibroblastic tissue representing organizing pneumonia c in the terminal bronchiole, H&E, × 200

Fig. 4

a–c Distribution of acute lung injury seen in electronic cigarette or vaping-associated lung injury. Diffuse involvement of the surgical lung biopsy by acute and organizing diffuse alveolar damage a. The diffuse nature of injury precludes any suggestion of airway centricity, H&E, × 20. Distinctly centrilobular distribution b of acute and organizing pneumonia, H&E, × 20. Following a more diffuse injurious insult, the healing phase of diffuse alveolar damage may mimic non-specific interstitial pneumonia c, H&E, × 100

Fig. 5

a, b Airspace macrophages seen in biopsy specimens from patients with electronic cigarette or vaping-associated lung injury. Marked accumulation of macrophage with distended and foamy cytoplasm is frequently encountered (arrow) a, H&E, × 400. Some of the macrophages may have pigment or pigmented material in the cytoplasm b, H&E, × 200

Fig. 6

a, b The histologic distinction between exogenous lipoid pneumonia and electronic cigarette or vaping-associated lung injury (EVALI) is dramatic and distinctive. Exogenous lipoid pneumonia shows numerous lipid vacuoles a, most of which are much larger than individual cells. There is associated fibrosis in which many of the droplets are embedded. Occasional macrophages contain lipid droplets within their cytoplasm. However, the droplets are much larger and more variable (arrow) compared to EVALI, H&E, × 100. Larger lipid vacuoles are surrounded by several multinucleated giant cells and a foreign body giant cell reaction (arrowhead) b, a feature not seen in EVALI, H&E, × 200