Pathologic Separation of Chronic Hypersensitivity Pneumonitis From Fibrotic Connective Tissue Disease–associated Interstitial Lung Disease

Chronic (fibrotic) hypersensitivity pneumonitis (HP) and fibrosing interstitial pneumonias associated with connective tissue disease (CTD-ILD) can be difficult to distinguish in biopsy specimens. To investigate features that might separate these entities, 2 pathologists blinded to the diagnoses reviewed 16 cases of chronic HP and 12 cases of CTD-ILD. Fifteen predefined parameters were examined by morphometric point counting, analysis/cm2 of lung tissue, or presence/absence. Germinal centers were present in a minority of patients, but favored a diagnosis of CTD-ILD (7/12 CTD vs. 2/16 HP; odds ratio, 9.80 [95% confidence interval, 1.50-63.4]; P=0.02). The number of lymphoid aggregates/cm2 (4.4±3.1 vs. 1.4±1.0; P=0.001), volume proportion of plasma cells (0.076±0.058 vs. 0.031±0.023; P=0.031), and plasma cell: lymphocyte ratio (1.03±0.71 vs. 0.35±0.22; P=0.001) were all significantly higher in CTD compared with HP. A diagnosis of HP was more common in the presence of peribronchiolar metaplasia (12/16 HP vs. 4/12 CTD; odds ratio, 6.00 [95% confidence interval, 1.15-31.2]; P=0.033) and in patients with a greater fraction of bronchioles showing peribronchiolar metaplasia (0.41±0.33 vs. 0.16±0.27; P

from #ORL-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2h4hOMQ