Abstract

The dendriform pulmonary ossification (DPO) is a rare condition of unknown origin in which branching mature bony spicules, usually containing marrow, are found within the alveolar septa. DPO manifests slow progression over many years or may remain unchanged; spontaneous regression has not been recorded. Most patients have no symptoms directly attributed to the ossification, although they may have symptoms due to the underlying fibrotic process. We experienced a case of DPO in 38 year-old-man who presented with cough and sputum for a month. The chest X-ray showed marked coarsened interstitial lung markings in both lungs, especially in the lower lobes. Open lung biopsy was done. Grossly, there were significant dendriform osseous structures. Histologically, branching arrays of mature bone were found in the interstitium and occasionally in alveolar spaces. Some bony trabeculae contained fatty or cellular marrow. The alveolar septa showed fibrous thickening with chronic inflammation. The transition between fibrosis and bone tissue was observed. Our case suggests that dendriform pulmonary ossification may be a rare special manifestation of chronic fibrosing interstitial inflammation of the lung. Osseous structures seem to derive from metaplastic bone formation in the vicinity of undergoing fibrous process.

• Keywords: Diffuse pulmonary ossification;Dendriform pulmonary ossification;Metaplastic ossification;Interstitial lung disease;