Histologic Changes

An elastic tissue stain at the edge of a consolidation shows the normal elastic framework of the lung, which includes the alveolar walls, blood vessels, and airways. To the left, new granulation tissue widens alveolar walls and narrows airways. Alveoli are narrowed in part from this encroachment and in part due to collapse because of impaired production of surfactant.

To the right, air spaces are enlarged. The cause of this change, which was apparent in the red areas of the gross lung specimen, will be explained below.

A higher magnification of the above picture shows an airway (center) almost completely filled with granulation tissue that has spread into adjacent air spaces (lower left). Many of the cells in the alveoli are detached epithelial cells, but a few are alveolar macrophages.

This H&E-stained section of the hyperemic lung that surrounded the consolidations shows two characteristic features at the arrows.

What are these features?

What is the explanation for the dilated air spaces?

What is the diagnosis of the entire lung disease?

Answers

Clinical summary Image 6

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Answers

 

What are these features? Hyaline membranes (lower arrow) and fibrin thrombus (upper arrow)

What is the explanation for the dilated air spaces? As a result of alveolar damage, alveoli collapse and respiratory bronchioles and alveolar ducts enlarge, setting the stage for honeycombing, which may occur if alveolar damage does not resolve. The fibrin thrombus resulted from the activation of the clotting system by alveolar damage.

 

 

What is the diagnosis of the entire lung disease? Organizing diffuse alveolar damage

Clinical summary Image 6

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