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Relationship between histopathological features and the course of idiopathic pulmonary fibrosis/usual interstitial pneumonia
  1. L Tiitto1,
  2. R Bloigu2,
  3. U Heiskanen1,
  4. P Pääkkö3,
  5. V L Kinnula4,
  6. R Kaarteenaho-Wiik1,3
  1. 1Department of Internal Medicine/Division of Pulmonary Diseases, University of Oulu and Oulu University Hospital, Oulu, Finland
  2. 2Medical Informatics Group, University of Oulu and Oulu University Hospital, Oulu, Finland
  3. 3Department of Pathology, University of Oulu and Oulu University Hospital, Oulu, Finland
  4. 4Department of Medicine, Division of Pulmonary Diseases, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  1. Correspondence to:
    Dr L Tiitto
    Department of Internal Medicine, P O Box 5000 (Kajaanintie 50), FIN-90014 University of Oulu, Finland; Leena.Tiitto{at}


Background: Fibroblastic focus (FF) is the typical histopathological feature of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP). A study was undertaken to analyse FF at diagnosis, to analyse the histopathological findings at necropsy, and to examine their association with the course of the disease.

Methods: A retrospective study was made of 76 UIP cases collected over a period of 30 years from one university hospital; 64 had idiopathic IPF. The surface area of one slide of each lung biopsy specimen was defined by image analysis and the total number of FF was quantified. The histological features of necroscopic lung samples were re-analysed in 11 cases. Clinical follow up information was obtained from the registers.

Results: Patients with ⩽50 FF/cm2 (n = 34) in the lung biopsy specimen had a median survival of 89 months (95% CI 38 to 140) compared with 49 months (95% CI 36 to 62) in those with >50 FF/cm2 (n = 42, p = 0.0358). Diffuse alveolar damage (DAD) was detected in 10 necropsy samples and almost prevented the histopathological confirmation of UIP in six cases. Accumulation of neutrophils occurred in nine cases. There was no association between FF at diagnosis and DAD at necropsy, or between FF and exacerbation of the disease before death.

Conclusions: The number of FF in lung samples before death is associated with poor survival but not with DAD, which is a common feature in necropsy specimens of patients with UIP. FF cannot predict an acute exacerbation of IPF.

  • CRP, C-reactive protein
  • DAD, diffuse alveolar damage
  • FF, fibroblastic focus
  • IPF, idiopathic pulmonary fibrosis
  • Tlco, carbon monoxide transfer factor
  • UIP, usual interstitial pneumonia
  • diffuse alveolar damage
  • fibroblast focus
  • idiopathic pulmonary fibrosis
  • usual interstitial pneumonia
  • histopathology

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  • Published Online First 12 June 2006

  • Supported by the Finnish Anti-Tuberculosis Association Foundation, Juselius Foundation, Maud Kuistila Foundation, and funding from Oulu and Helsinki University Hospitals.

  • Competing interests: none declared.