[Contribution of pathology to diagnosis of fibrosing lung diseases]

Area of Science:

• Pulmonary pathology
• Histopathology
• Fibrosing lung diseases

Context:

• Morphologic diagnosis of fibrosing lung disease is complex.
• Key diagnostic criteria include inflammation type, lesion localization, and microtopographic patterns.
• Understanding these patterns is crucial for accurate diagnosis.

Purpose:

• To outline the primary criteria for diagnosing fibrosing lung disease.
• To detail the six recognized microtopographic patterns of inflammation and fibrosis.
• To compare the diagnostic utility of open lung biopsies versus bronchoalveolar lavage.

Summary:

• Fibrosing lung disease diagnosis hinges on inflammation characteristics, lesion site, and specific microtopographic patterns (perilobular, intraalveolar, alveoloseptal, bronchiolitic, vasculitic, bronchiolectatic).
• These patterns correlate with distinct pathogenetic mechanisms, with some diseases exhibiting a predominant pattern (e.g., sarcoidosis) and others a combination.
• Open lung biopsies, when unfolded, best visualize these microtopographic patterns, whereas bronchoalveolar lavage findings, particularly T-lymphocyte overrepresentation, may not accurately reflect lung tissue composition.

Impact:

• Provides a framework for classifying fibrosing lung diseases based on distinct histopathological patterns.
• Highlights the limitations of bronchoalveolar lavage in assessing the true inflammatory infiltrate.
• Emphasizes the superior diagnostic value of open lung biopsies for detailed microtopographic analysis in fibrosing lung disease.