In the Verhoeff-Van Gieson stain, elastin fibers appear very pale and do not contrast well with the background. Which of the following is a documented cause?

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Elastin is colored by Verhoeff’s hematoxylin in the Verhoeff–Van Gieson combo, so if the elastic fibers look very pale and lack contrast, a documented cause is an improperly prepared Verhoeff’s hematoxylin. When this dye solution is off—wrong concentration, incorrect pH, inadequate oxidation, or using an old/degraded reagent—the mordant-dye complex doesn’t form correctly, and elastin fails to take up the stain darkly. The Van Gieson counterstain would still color other components as usual, so the key issue remains with the elastic-stain step. To troubleshoot, refresh and verify the Verhoeff’s hematoxylin preparation (pH, oxidation, and staining time). Other options would alter other aspects of the stain pattern, such as background color or general tissue integrity, but they don’t specifically explain pale elastin.