Dendriform ossification consists of linear and branching deposits of metaplastic bone in the pulmonary interstitium that evolves from fibrosis, often contains bone marrow, and is typically seen in older men. Nodular ossification may also occur as ossified or ossific bodies and is associated with venous hypertension. Nodules of metaplastic ossification consist of mature bone, generally without bone marrow elements, and are typically intra-alveolar.