title: Metaplastic ossification in the cartilage of the bronchus of a patient with chronic multi-drug resistant tuberculosis: a case report.
abstract: BACKGROUND
  Pulmonary ossification has been rarely observed in pulmonary fibrosis and in some chronic respiratory diseases such as chronic obstructive pulmonary disease. We report here a metaplastic ossification in the bronchial cartilage of a patient with multi-drug resistant tuberculosis.
  
  
  METHODS
  We report the case of a 41-year-old Asian man from Korea with chronic multi-drug resistant tuberculosis with a rare focus of bone formation from the cartilage of a bronchus subtending an active cavity. The patient had a large multi-lobed, thick-walled cavitary tuberculosis lesion in his left upper lobe. Severe infiltration of his lymphocytes and epithelioid cells, along with some giant cells and neutrophils, was observed in the patient's bronchial wall. Desquamated bronchial epithelium and acid-fast bacilli were found inside his bronchus. A small focus of bony metaplasia was found in the cartilage of his bronchial wall. Histopathological examination confirmed calcification and showed hematopoietic cells forming in his marrow cavity.
  
  
  CONCLUSIONS
  Chronic inflammation in the lungs of our patient, caused by underlying tuberculosis, probably played a role in the development of osseous metaplasia from the associated cartilage of the bronchial wall.
authors.affiliation: Division of Immunopathology and Cellular Immunology, International Tuberculosis Research Center, Masan, Republic of Korea. syeumkr@gmail.com.
authors.forename: Seok-Yong
authors.initials: SY
authors.lastname: Eum
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Kong
authors.forename: Bo-Young
authors.initials: BY
authors.lastname: Jeon
authors.forename: Sang-Nae
authors.initials: SN
authors.lastname: Cho
authors.forename: Jhingook
authors.initials: J
authors.lastname: Kim
authors.forename: Laura E
authors.initials: LE
authors.lastname: Via
authors.forename: Clifton E
authors.initials: CE
authors.lastname: Barry Iii
authors.forename: Won-Jung
authors.initials: WJ
authors.lastname: Koh