78 Chapter 5 Figure 7. A, Section of skin biopsy showing part of surface displaced to deeper part of biopsy specimen. Insets show details of squamous cell carcinoma in situ. This displacement may have been caused by cutting on microtome. B, Pseudolipoid change1 present (central air bubbles after bronchial biopsy (hematoxylin-eosin, original magnifications x2.5 [A] and x20 [insets A, and B]). Discussion This study describes the effect of 4 patterns of ex vivo artifacts occurring in the lung. Three of the artifact patterns have to some extent been described before. Pseudolipoid change is another artifact representing air bubbles after bronchial biopsy as described before89 (Figure 7, B). In the same textbook89, crinkling and telescoping of epithelium are ascribed to airway compression. In our opinion these findings are a combination of the ex vivo artifacts ‘‘collapse’’ and ‘‘contraction.’’ Recognizing ‘‘contraction’’ artifact may affect our perception of morphologic lung changes in asthma. Increased smooth muscle mass is consistently seen and a feature of airway remodeling; perhaps a degree of this is secondary to ex vivo artifact107,108. Intuitively, the morphology of contraction artifact is associated with functional airway obstruction. However, in most patients with folded bronchiolar epithelium there is no airway obstruction, except in airway-related diseases such as asthma and constrictive bronchiolitis, where other characteristics (increased luminal mucus, inflammation, thickened basement membrane, and/or fibrosis) explain the obstruction. The question arises as to what extent this artifact has been taken into account in previous studies measuring basement membrane thickness109. In many asthma studies smooth muscle area is measured relative to basement membrane length, giving reproducible results for larger airways (but not always for smaller airways with perimeter of basement membrane, 4 mm)110. The contraction artifact is specifically present at the bronchiolar level, possibly being another confounder in this study, beside variation between centers in inflation procedures, presence or absence of mucus in bronchiolar lumen, selection differences in airway sizes, and differences in calibration of
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