What accounts for the brown color?
Gross and Histologic Changes
This slice of lung shows a brownish area, about 1.5 cm in extent, in an otherwise pale parenchyma. Many other similar areas were present throughout the lungs. Firm nodules, 2 to 5 mm in diameter, could be felt within these brown areas. The nodule shown (opposing arrows) is 5 mm in diameter. The surrounding pale parenchyma was finely granular to palpation. The pleura is at the top. Subpleurally to the right is a wedge-shaped consolidation with black pigment, 1.5 cm in extent, which is an infarct (arrow).
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What accounts for the brown color? | ||||||||
This section, which is stained with the elastic van Gieson stain, shows a basic lesion in this case. What is it?
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A. Plexiform lesion B. Arterial thrombus C. Venous narrowing and capillary congestion D. Interstitial fibrosis with inflammatory vascular narrowing | ||||||
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What accounts for the brown color? Answer: Hemosiderin, a blood breakdown product, gives the brown color. The development of the nodule is illustrated on the following pages. | ||||||||
Answer--C. Venous narrowing and capillary congestion
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A. Plexiform lesion B. Arterial thrombus D. Interstitial fibrosis with inflammatory vascular narrowing
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A and B, which are arterial lesions, are wrong because the central vascular structure is a vein with a single elastic layer except at the arrow, where the wall is arterialized; that is, inner and outer elastic layers surround a muscular media. Interstitial fibrosis (D) would show collagenization of the alveolar walls. Here the adjacent alveoli are widened by dilated capillaries with little pink-staining collagen.
Clinical
summary