Lung ossification: an orphan disease.

Diffuse pulmonary ossification (DPO) is a rare entity which is characterized by metaplastic bone formation in the lung parenchyma. It is an uncommon condition without significant symptoms, which is usually diagnosed on autopsy. Diffuse pulmonary ossification can be easily misdiagnosed as one of interstitial lung diseases due to diffuse pulmonary lesions. Two types of diffuse ossification are described in medicine: dendriform and nodular. In this article, the authors present a patient with persistent pneumothorax who underwent investigation of the cause of his disease and a diagnosis of DPO was revealed.