Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Dendriform pulmonary ossification
- Radiologic Findings
- Fig 1. Chest PA shows diffuse reticulonodular opacities predominantly in the peripheral and lower lung zone.
Fig 2, 4. Axial and coronal CT scans with lung window setting show tiny nodules along the interstitium with linear or branching opacities in both lungs.
Fig 3, 5. Axial and coronal CT scans with mediastinal window setting show foci of calcifications in some of the nodules and linear opacities.
Fig 6. Compared with the coronal CT scans performed 2 years later, tiny nodules and linear opacities slightly increased.
The patient underwent bronchoscopic biopsy and the pathologic examination confirmed the presence of multifocal ossification.
- Brief Review
- Pulmonary ossification is an unusual condition of unknown etiology and has been recognized in the following 2 forms: granular (nodular) and dendriform. The nodular type of ossification has been linked to passive congestion due to chronic heart failure, mitral stenosis, and hypertrophic subaortic stenosis. Dendriform pulmonary ossification (DPO) has been most often described in association with primary lung diseases including idiopathic pulmonary fibrosis. DPO is less common than the nodular type.
DPO is classified along with nodular pulmonary ossification as a form of diffuse pulmonary ossification. DPO and nodular pulmonary ossification occur in very different clinical situations and have unique CT appearances. Nodular pulmonary ossification, in which ectopic bone is present in the alveolar spaces, occurs in the setting of chronically elevated pulmonary venous pressures particularly due to chronic mitral stenosis or left heart failure. Nodular pulmonary ossification represents pathologic ossification in areas of chronic airspace hemosiderosis and organizing pneumonia; histologically, the bone elements do not contain marrow elements (fat or hematopoietic cells). The CT appearance is that of small centrilobular nodules, often of high attenuation, with a lower lobe predominance that may coalesce. DPO is a process in which metaplastic ectopic bone is present within the lung. Pathologically, the bony deposits are in the alveolar walls and the peripheral interstitium, including the interlobular septa and subpleural and perifissural regions; the bony spicules form a contiguous branching pattern, resulting in a lattice-like appearance or dendrite. The CT appearance of DPO is characteristic, but there have been limited descriptions of CT findings in patients who do not have pulmonary fibrosis. Small nodules, several millimeters in diameter, are present in the peripheral interstitium (interlobular septa and subpleural and perifissural spaces) and form contiguous, branching structures resembling tree branches in the affected areas. The deposition of DPO correlates with the underlying structure of the parenchymal peripheral interstitium. Significant lobular distortion, traction bronchiolectasis, and honeycombing are absent. High attenuation, reflecting the underlying ossification, can be identified in some but not all nodules; microscopic ossification may not be visible on CT, and thin sections and maximum-intensity-projection images are helpful in the detection of small high-attenuation foci.
No specific treatment or management guidelines are published for patients with DPO alone. Bronchoscopy with transbronchial biopsies is a useful tool for diagnosing dendriform pulmonary ossification.
- References
- 1.↵ Lara JF, Catroppo JF, Kim DU, da Costa D. Dendriform pulmonary ossification, a form of diffuse pulmonary ossification: report of a 26-y autopsy experience. Arch Pathol Lab Med 2005;129(3):348–353.
2. Gruden JF, Green DB, Legasto AC, Jensen EA, Panse PM. Dendriform Pulmonary Ossification in the Absence of Usual Interstitial Pneumonia: CT Features and Possible Association With Recurrent Acid Aspiration. AJR Am J Roentgenol. 2017 Dec;209(6):1209-1215. doi: 10.2214/AJR.17.18063. Epub 2017 Oct 5. PMID: 28981359.
3. Egashira R, Jacob J, Kokosi MA, Brun AL, Rice A, Nicholson AG, Wells AU, Hansell DM. Diffuse Pulmonary Ossification in Fibrosing Interstitial Lung Diseases: Prevalence and Associations. Radiology. 2017 Jul;284(1):255-263. doi: 10.1148/radiol.2017152419. Epub 2017 Feb 9. PMID: 28182861.
4. Martinez JB, Ramos SG. Dendriform pulmonary ossification. Lancet 2013;382(9904):e22.
- Keywords