Diffuse pulmonary ossification is a rare entity that presents with bone formation within the lung parenchyma. Patients are generally asymptomatic and diagnosis is usually made at autopsy, but patients can rarely present with dyspnea, cough, and hemoptysis. Although a specific etiology has not been established, it has been associated with acute and chronic lung disease, heart disease and other systemic disorders. Diffuse alveolar hemorrhage (DAH) can complicate a large number of clinical conditions and has not previously been associated with pulmonary ossification. We describe a case of diffuse pulmonary ossification in association with diffuse alveolar hemorrhage in a man with significant occupational metal exposure.
A 38-year-old African-American male presented with flu-like symptoms associated with frank hemoptysis. Although the flu-like symptoms resolved he continued to have daily morning hemoptysis that did not resolve after treatment for bronchitis with a macrolide and fluoroquinolone. He was otherwise asymptomatic, denied other respiratory symptoms and he was able to exercise 2–3 times a week without limitation. His past medical history is otherwise unremarkable. Social history is significant for a fifteen- year career working with metals as a fabricator and welder with known exposures to steel, iron, and acetylene used for welding. A NIOSH- approved mask was worn during all occupational exposures and he denied any additional known exposure to other fumes, dusts, or chemicals. A PPD was negative and three sputum samples were negative for AFB and cultures. Radiographic studies revealed bilateral left greater than right pulmonary densities. Transthoracic echocardiogram was unremarkable. Bronchoscopy revealed birefringenet foreign body granulomata with foci of metaplastic bone formation as well as hemosiderin-laden macrophages consistent with diffuse alveolar hemorrhage. The patient proceeded to wedge biopsy that showed metaplastic bone formation with hemosiderin-laden macrophages and birefringent anthrasilicotic dust macules with rounded ferruginous bodies.
Pulmonary ossification is an uncommon process of bone formation within the lung parenchyma. It is has been described as dendriform or nodular calcification in patients with inflammatory lung diseases as well as cardiac and other systemic conditions. Diffuse alveolar hemorrhage can complicate a large number of clinical conditions and has not previously been associated with pulmonary ossification. We describe a case of dendriform pulmonary ossification in association with diffuse alveolar hemorrhage in a man with significant occupational metal exposure. The pathophysiology of dendriform pulmonary ossification has unknown but case reports suggest fibrosis as a precursor to ossification in the parenchyma. It is hypothesized that robust fibroblastic activity leads to metaplasia into osteoblasts, a process that is well-known to occur in other tissues. The present case is unusual in the diffuse nature of the ossification, the finding of birefringent anthrasilicotic dust macules with rounded ferruginous bodies in the biopsy specimen, and his known occupational hazards working with metals and as a welder. This suggests a possible inhalational etiology for pulmonary ossification.
Diffuse alveolar hemorrhage can complicate a large number of clinical conditions and we report the first known association with dendriform pulmonary ossification, a rare entity of unknown etiology and pathogenesis. In addition, our case report suggests a possible role of occupational metal exposure as an inciting event. Further studies and occupational health observations will be necessary to further elucidate the relationship between occupational exposures and dendriform pulmonary ossification.
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