Feature | CTD | Chronic HP |
Cellular (lymphocytic and/or plasmacellular) interstitial infiltrate | + | + |
Plasma cells | + | + |
Cellular bronchiolitis | + | + |
Centrilobular fibrosis, with or without bridging fibrosis between bronchioles and pleura | − | + |
Pleuritis | + | − |
Small interstitial/peribronchiolar granulomas | –# | + |
Coexistence of more than one pattern in the same biopsy | + | −/+ |
+: positive; –: negative. #: except in Sjögren’s syndrome, in which small granulomas can be found.