Table 2 Pathologic features of nonfibrotic HP.

In most cases distinctly bronchiolocentric mild chronic interstitial inflammation with normal parenchyma away from bronchioles

Minority of cases show a cellular NSIP pattern

For either pattern:

 Lymphocytes > plasma cells

 Lymphoid aggregates few to nonexistent

 Germinal centers rare to nonexistent

 Granulomas/giant cells in the majority of cases

 Granulomas/giant cells usually interstitial but can be found in airspaces near bronchioles

 Schaumann bodies sometimes present and are equivalent to granulomas/giant cells