title: [Pathological changes of lungs in patients with severity acute respiratory syndrome].
abstract: OBJECTIVE
  To evaluate the progression in morphologic changes of lungs in SARS patients.
  
  
  METHODS
  Four cases of SARS with lung tissue samples available (including one for ultrastructural examination) were enrolled into the study. Histochemical study for VG, Masson, reticulin, orcein, PAS, sirius red stains and immunohistochemical study for vimentin, desmin, smooth muscle actin, HHF-35, CD34, F8, collagen types I and III were also performed.
  
  
  RESULTS
  According to the morphologic changes, lung lesions in SARS were subcategorized into 3 phases: acute exudative inflammation, fibrous proliferation and the final fibrotic stage. Two cases belonged to the acute exudative phase, in which the course was less than 20 days. The principal lesions consisted of acute alveolar exudative inflammation, hyperplasia of alveolar epithelium, necrosis, alveolar hyaline membrane formation, alveolar desquamation and focal fibroplasia. The acute exudative protein was PAS-positive. There was an increase in reticulin fiber formation. The reactive fibroblasts were highlighted by desmin and vimentin. One case belonged to the fibroproliferative stage, in which the course was around 25 days. Major lesions included proliferative interstitial pneumonia with early pulmonary fibrosis. There was also evidence of organizing pneumonia, with an increase in reticulin fiber formation, which had a glomeruloid appearance on special stain. The mesenchymal cells showed either myofibroblastic (which expressed desmin, HHF-35, smooth muscle actin and vimentin) or fibroblastic (which expressed vimentin only) differentiation. Fibroelastosis and fibroplasia was also noted. The remaining case belonged to the fibrotic stage, in which the course was around 75 days. The main features included diffuse fibrosis and honeycomb change, which were highlighted by sirius red stain. Immunohistochemistry showed mainly types I and IV collagen fibers. In all lesions, there was also an increase of number of CD68-positive macrophages.
  
  
  CONCLUSIONS
  The morphologic progression in lungs of SARS patients is characterized by the development of increased fibrosis. The primitive mesenchymal cells, hyperplastic alveolar epithelial cells and macrophages play an important role in the pathogenesis.
authors.affiliation: Department of Pathology, General Hospital of Guangzhou Command, Guangzhou 510010, China.
authors.forename: Ri-quan
authors.initials: RQ
authors.lastname: Lai
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Feng
authors.forename: Ying-ying
authors.initials: YY
authors.lastname: Gu
authors.forename: Huang-wen
authors.initials: HW
authors.lastname: Lai
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Zhou-cai
authors.initials: ZC
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Guo-qin
authors.initials: GQ
authors.lastname: Chen
authors.forename: Chuan-hong
authors.initials: CH
authors.lastname: Yang
authors.forename: Tong
authors.initials: T
authors.lastname: Yang
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D024042:Collagen Type I / Q000378:metabolism; D003893:Desmin / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000473:pathology; D045169:Severe Acute Respiratory Syndrome / Q000378:metabolism / Q000473:pathology*; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D024042:Collagen Type I; D003893:Desmin; D014746:Vimentin