Lung Macrophages Accumulate Novel Cytosolic Inclusions With Vaping: A Case Report From an Asymptomatic Habitual Vaper

Abstract Background: The effects of habitual vaping on lung health are currently unknown. Acute e-cigarette/vaping product use-associated lung injury (EVALI) has been highlighted recently in numerous cases across the U.S. Several EVALI case reports highlight alterations in lung macrophages, justifying investigation of this key immune sentinel of the lung in habitual vape device users. Methods: Histologic (Oil Red O stain) and transmission electron microscopy were used to evaluate BAL macrophages obtained from a habitual and asymptomatic 25-year-old female vaper. Results: Oil Red O stain evaluation of BAL macrophages demonstrate a prevalence of cells with high lipid accumulation in multiple, discrete cytoplasmic foci. At ultrastructural level, this translated in membrane-bound compartments filled with osmiophilic material of various densities segregated along curved phase separation lines reminiscent of suspensions of immiscible fluids. Conclusions: This ultrastructural pattern is unlike any other previously reported in aspiration syndromes and may represent a defining diagnostic feature of vapers.