These are referred to as “poorly formed” or “loose” granulomas and are characteristically seen in hypersensitivity pneumonitis (HP), granulomatosis with polyangiitis (GPA), foreign body reactions, lymphocytic interstitial pneumonia, and others.

Small, poorly formed granulomas or multinucleated giant cells are randomly scattered within the interstitial inflammation and/or bronchiolar walls. The granulomas can be small and difficult to identify and often consist of only a few loosely aggregated histiocytes 108 ( Figure 5, D ).

Granulomas are usually harmless. They often go away on their own without treatment. Calcified granulomas (ones that have formed calcium deposits) might be less likely to go away. You may notice the same calcified granulomas noted on imaging reports over time.

The histological triad of hypersensitivity pneumonitis includes peribronchiolar chronic inflammation, poorly formed small interstitial nonnecrotising granulomas and foci of organising pneumonia. Multinucleated giant cells are randomly scattered within the interstitial inflammation and/or bronchiolar walls.

In the non-fibrotic HP form, pathologic findings are poorly formed non-caseating granulomas with bronchiolocentric location, inflammatory lymphocytes infiltrates, and foci of organizing pneumonia consisting of small airways filled with fibroblastic plugs (Masson bodies) .