INTRODUCTION: Bone metaplasia is a rare finding in the setting of Interstitial lung disease (ILD) are usually discovered at autopsy. We describe a series of four cases of ILD with bony metaplasia in their lung biopsy.
CASE PRESENTATION: Case 1: A 59 year old Caucasian female presented with chronic cough and dyspnea. High resolution computed tomogram (HRCT) chest revealed diffuse bilateral sub-pleural interstitial fibrosis (peripheral and basilar distribution) with evidence of progression on follow-up imaging along with focal areas of punctuate calcification in the lung bases. Surgical lung biopsy (SLB) confirmed “Usual interstitial pneumonia (UIP) with focal osseous metaplasia”. Case 2: 84 old Caucasian male presented with dyspnea. HRCT findings showed basilar and peripheral predominant sub-pleural interstitial fibrosis consistent with UIP pattern. Diffuse punctuate areas of calcification amidst the sub-pleural fibrosis were seen. Pathology from SLB confirmed UIP with extensive metaplastic bone formation. Case 3: A 71 year old Hispanic male presented with Chest pain and dyspnea, diagnosed with pulmonary fibrosis with dendriform pulmonary ossification (DPO). HRCT showed marked basilar peripheral sub-pleural fibrosis with diffuse punctuate calcification. Pathology revealed pulmonary fibrosis along with pan-acinar emphysema and dendriform pulmonary ossification. Case 4: A 64 year old Hispanic male with chronic respiratory symptoms presented with acute respiratory failure. CT chest revealed severe diffuse interstitial pneumonia. Pathology from SLB revealed organizing pneumonia, diffuse alveolar damage along with honeycombing, advanced fibrosis and heterotopic bone formation consistent with a diagnosis of acute exacerbation of Idiopathic Pulmonary fibrosis.
DISCUSSION: Pulmonary ossification is reactive bony metaplasia associated with long standing pulmonary injury and with no specific known clinical implication. Most cases reported in literature are discovered at autopsy. Its pathological significance remains unknown. 3 of 4 patients had evidence of “punctuate calcification” amidst sub-pleural fibrosis.3 of 4 patients had clear cut clinical, radiographic and pathological features of UIP. The other patient demonstrated advanced pulmonary fibrosis but could not be accurately characterized as UIP. Therefore, this important pathological finding may support the diagnosis of UIP.
CONCLUSIONS: 1. Bony metaplasia in ILD may support the diagnosis of UIP. 2. “Punctate calcification” in areas of fibrosis may suggest the presence of this pathological finding. Bony metaplasia in the setting of ILD is under-recognized and under-reported. Its pathological significance remains unknown. Creation of pathological registry may improve our understanding of this finding.
Reference #1 Kim TS, Han J, Chung MP, Chung MJ, Choi YS. Inflammation and angiogenesis in fibrotic lung disease. Eur Radiol. 2005 Aug;15(8):1581-5. Epub 2005 Apr 23.
Reference #2 2. Bai P, Sun YC, Chen DN, Jin JM, Zhuo J, Liu HG.Idiopathic diffuse pulmonary ossification: a case report and review of the literature. Zhonghua Jie He He Hu Xi Za Zhi. 2009 Aug; 32(8):588-92.
Reference #3 Peros-Golubicić T, Tekavec-Trkanjec J. Diffuse pulmonary ossification: an unusual interstitial lung disease. Curr Opin Pulm Med. 2008 Sep;14(5):488-92.
DISCLOSURE: The following authors have nothing to disclose: Nastran Hashemi, Narinder Gill, Vijay Balasubramanian
No Product/Research Disclosure Information