Archives of pathology & laboratory medicine
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Arch. Pathol. Lab. Med. · Dec 2020
ReviewCentrilobular Fibrosis in Fibrotic (Chronic) Hypersensitivity Pneumonitis, Usual Interstitial Pneumonia, and Connective Tissue Disease-Associated Interstitial Lung Disease.
Various pulmonary diseases can produce centrilobular (peribronchiolar) fibrosis, which may be isolated or associated with other patterns of more diffuse fibrosis. The major forms of interstitial lung disease in which centrilobular fibrosis is found are fibrotic (chronic) hypersensitivity pneumonitis, connective tissue disease-associated interstitial lung disease, and (a disputed issue) usual interstitial pneumonia/idiopathic interstitial fibrosis. ⋯ In a specially constructed multidisciplinary discussion exercise, it was found that peribronchiolar metaplasia affecting more than half the bronchioles or more than 2 foci of peribronchiolar metaplasia per square centimeter of biopsy area was strongly associated with a confident diagnosis of fibrotic hypersensitivity pneumonitis. Giant cells or granulomas were only found in cases with a greater than 50% diagnostic confidence in hypersensitivity pneumonitis. Conversely, greater numbers of fibroblast foci per square centimeter and increasing measured amounts of subpleural fibrosis favored a diagnosis of usual interstitial pneumonia. Recent data also suggest that centrilobular fibrosis can be found in usual interstitial pneumonia, although the presence of centrilobular fibrosis statistically favors an alternate diagnosis. Connective tissue disease is a major confounder because many patterns are very similar to fibrotic hypersensitivity pneumonitis or usual interstitial pneumonia. Genetic abnormalities, such as the MUC5B minor allele overlap, in these conditions and at this point cannot be used for discrimination. Thus, the separation of fibrotic hypersensitivity pneumonitis and usual interstitial pneumonia remains a difficult problem. Accurate biopsy diagnosis of all of these diseases requires correlation with imaging and clinical findings, and is crucial for treatment.
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Arch. Pathol. Lab. Med. · Dec 2020
ReviewE-Cigarette or Vaping Product Use-Associated Lung Injury: A Review for Pathologists.
Vaping is the inhalation of heated aerosol from a small battery-powered device as a method to deliver nicotine or other substances. A recent outbreak of severe respiratory illness primarily in the United States has put a spotlight on vaping and its potential risks. ⋯ Most cases of vaping-associated lung injury have been linked to vaping products containing tetrahydrocannabinol or other cannabinoids. Lung biopsies show a spectrum of nonspecific acute lung injury patterns (organizing pneumonia, diffuse alveolar damage, acute fibrinous, and organizing pneumonia, or combinations of the above), accompanied by prominent, foamy macrophage accumulation. Injury is usually accentuated around small airways. Lipid-laden macrophages can be identified in bronchioloalveolar lavage fluid in most patients and these can be highlighted using lipid stains, such as oil red O, but the clinical utility of this finding remains unclear, as lipid-laden macrophages can be seen in a wide variety of processes and should not be relied upon to make the diagnosis. Classic histologic features of exogenous lipoid pneumonia have not been identified in tissue samples. Lightly pigmented macrophages, similar to those seen with traditional cigarette smoking, are present in some cases but are usually a minor feature. To date, no specific pathologic features for vaping-related injury have been identified, and it remains a diagnosis of exclusion that requires clinicopathologic correlation.
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Arch. Pathol. Lab. Med. · Dec 2020
ReviewTransbronchial Cryobiopsy in the Diagnosis of Fibrotic Interstitial Lung Disease.
Transbronchial cryobiopsy is an emerging procedure to obtain lung tissue for diagnosis of interstitial lung disease and has gained popularity because it is less invasive and has a lower rate of complications compared with nonselective surgical lung biopsy. ⋯ While the diagnostic yield of transbronchial cryobiopsy is slightly lower than surgical lung biopsy, a growing amount of literature suggests that with a multidisciplinary approach cryobiopsy provides diagnostic and prognostic information approaching that of surgical lung biopsy with lower morbidity and mortality.