Fibrotic Lung Diseases

Question 1

Cholesterol clefts

Answer 1

Nonspecific deposits of cholesterol

These can occur almost anywhere, including within giant cells!

Question 2

Answer 2

This is hypersensitivity pneumonitis

Note that the air spaces are preserved, but they are further between due to an expansion of the interstitium

The interstitium contains a lymphocytic infiltrate and giant cells, forming granulomas in places.

Note that without the giant cells, this could be a presentation of non-specific interstitial pneumonitis

Question 3

Answer 3

This image shows a dome-shaped fibroblastic focus within the interstitium of the lung parenchyma. These foci can be detected on low-power by their gray appearance relative to the eosinophilic background.

This is highly suggestive of usual interstitial pneumonia

Question 4

Major features of UIP

Answer 4

• Pathology is most dense in the sub-pleural space with relative sparing of the central lung tissue
• Patchy distribution with areas of involved and uninvolved lung tissue
• Microscopic honeycombing: cystic dilation of bronchial space with metaplasia of respiratory epithelium
• Temporal heterogeneity with areas of older dense fibrosis, areas of active fibroblastic proliferation and activity, and uninvolved lung
• With regards to treatment: do NOT respond to steroids, but do respond partially to new antifibrotic medications (nintedanib)