Question

A female presents with a history of progressive breathlessness. Histology shows heterogeneous patchy fibrosis with several fibroblastic foci. The most likely diagnosis is:

• A. Cryptogenic organizing pneumonia
• B. Non-specific interstitial pneumonia
• C. Usual interstitial pneumonia
• D. Desquamative interstitial pneumonia

Hint:

Patchy heterogeneous fibrosis plus fibroblastic foci equals UIP.

Answer 1

The Correct Option is C

Step 1: Pick out the diagnostic clues. The two key phrases are heterogeneous patchy fibrosis and fibroblastic foci.
Step 2: Match these to a pattern. Usual interstitial pneumonia (UIP), the histologic substrate of idiopathic pulmonary fibrosis, is defined by patchy, non-uniform fibrosis with areas of old scarring next to normal lung (temporal and spatial heterogeneity), plus scattered fibroblastic foci of active young collagen. This is the exact description given.
Step 3: Exclude non-specific interstitial pneumonia. NSIP shows uniform, homogeneous fibrosis or inflammation and characteristically lacks fibroblastic foci. The patchy heterogeneous pattern rules NSIP out.
Step 4: Exclude the others. Cryptogenic organizing pneumonia shows plugs of granulation tissue in the airspaces (Masson bodies), not interstitial fibroblastic foci. Desquamative interstitial pneumonia shows airspaces filled with pigmented macrophages and is smoking related, again without the heterogeneous fibrosis pattern.
Conclusion: Heterogeneous fibrosis with fibroblastic foci is UIP. The answer is option C.