Histologic Changes

Within the alveolar parenchyma were multiple foci in which the alveolar walls were thickened and appeared to encroach on the alveolar spaces. Individual capillaries were dilated compared to those in the surrounding normal alveolar walls.

A thick-walled vein lies at the upper right and a narrowed artery at the lower left. EVG stain

This H&E-stained section shows a similar view at higher magnification. Note again the enlargement of the capillaries in the widened alveolar walls. These capillaries (arrow) have several red cells in a diameter of the lumen compared to the capillaries outside the lesion (upper left), which have one or none.

Note the intimal thickening of the vein that shows arterialization of the wall at the arrow. Arterialization represents thickening of the muscular media and delineation by inner and outer elastic layers. Note also the narrowed venule to the left of the vein (arrow). Elastic van Gieson stain.

These cellular areas with dilated capillaries had little hemosiderin.

Clinical summary Image 3

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