Nothing but lung and bones: Longitudinal evolution and quantitative analysis in a case of idiopathic diffuse pulmonary ossification

A 77-year-old Caucasian man, a former surveyor in a chemical company, underwent a chest X-ray (CXR) as a follow-up exam for a melanoma of the back, surgically removed. CXR showed interstitial thickening in both lower lobes; then, a high-resolution computed tomography of the chest (HRCT) was performed to further investigate these findings, revealing multiple small, calcified nodules with branching appearance at both lung bases. Clinical examination and exposure history were negative, except for a decrease in diffusing capacity for carbon monoxide resulting from pulmonary function tests. Surgical lung biopsy was performed; histology revealed numerous nodules and branching tubules of bone tissue, some of which with marrow elements. After multidisciplinary discussion of the case, a diagnosis of idiopathic diffuse pulmonary ossification (DPO) was considered. Clinical status of the patient was stable over time, despite the increase in extent of calcifications. DPO is an uncommon condition that should be considered in different clinical-radiological settings; multidisciplinary discussion is essential for the final diagnosis.