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).

What accounts for the brown color?

Answer

 

This section, which is stained with the elastic van Gieson stain, shows a basic lesion in this case. What is it?

A. Plexiform lesion

B. Arterial thrombus

C. Venous narrowing and capillary congestion

D. Interstitial fibrosis with inflammatory vascular narrowing

Answer

Clinical summary Image 2

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Answer

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

A. Plexiform lesion

B. Arterial thrombus

D. Interstitial fibrosis with inflammatory vascular narrowing

 

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 Image 2

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