Histologic Changes

A photo of an entire section shows the distribution of fibrosis, which encroaches on the alveolar parenchyma from the pleura (left), bronchovascular bundles (B), and interlobular septa (S). Note the complete shrinkage of a lobule (dark pink) at the lower left.

Below, at higher power, several features of the disease can be seen. Answer the following questions.

1. Characterize the air spaces and alveolar walls around the black arrow. Answer

2. How do the alveolar walls at the green arrow differ from those around the black arrow with respect to lining cells, wall thickness, and cellularity? Answer

3. What has happened to alveolar walls and spaces at the brown arrow? Answer

4. Compare the type of matrix around cells in the left upper quadrant with that at the blue arrow. Answer

5. What is the structure at the red arrow? Answer

6. Give a descriptive diagnosis. Answer

Below is an active lesion. Its characteristic features are listed.

1. Widened, chronically inflamed alveolar walls

2. Type II cell hyperplasia

3. Increased alveolar macrophages and some PMNs (darker cells without visible cytoplasm) in air spaces

The marked widening of the alveolar wall at the mid bottom (arrow) represents early proliferation of fibroblasts from the wall into the exudate--beginning organization.

What is this entire process called? Answer

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Answer 1. These air spaces and alveolar walls are normal.






























Answer 2. Even at low power the hypertrophy of the type II cells can be seen. The alveolar walls are thickened by inflammatory cells (not collagen).































Answer 3. Widened alveolar walls are becoming confluent and obliterating the air spaces.






























Answer 4. The matrix is pale and non-collagenized in the left upper quadrant but is pink and collagenized at the blue arrow.
































Answer 5. A lymphoid aggregate































Answer 6: Patchy cellular and fibrosing interstitial pneumonia






























Answer: Alveolitis. This is the alveolitis lesion referred to in the name fibrosing alveolitis.

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