Histopathology of pulmonary fibrosis and dendriform pulmonary ossification

Lung biopsy of patient with pulmonary fibrosis and histopathologic evidence of dendriform pulmonary ossification.
(A) Microscopic analysis of the lung tissue shows extensive, mostly airspace, involvement of the lung parenchyma by bone formation (osseous metaplasia) (asterisks). The adjacent alveolar septa show patchy expansion by mature collagen and chronic inflammation (arrows).
(B) Another area of the lung tissue showing chronic fibrosis and scattered fibroblastic foci (thick arrows). No granulomas or honeycombing were identified.