Chronic hypersensitivity pneumonitis in Japan: a nationwide epidemiologic survey

J Allergy Clin Immunol. 1999 Feb;103(2 Pt 1):315-20. doi: 10.1016/s0091-6749(99)70507-5.


Background: Pulmonary fibrosis inevitably develops in patients with chronic hypersensitivity pneumonitis (HP).

Objective: We conducted a nationwide epidemiologic study in Japan to evaluate the frequency and clinical characteristics of chronic HP.

Methods: This report is on 36 cases of chronic HP, including 10 patients with summer-type HP, 5 patients with home-related HP, 7 patients with bird fancier's lung, 5 patients with isocyanate-induced HP, 4 patients with farmer's lung, and 5 patients with other types of chronic HP. Chronic HP was further subgrouped into 2 types: one type of patients were first seen with chronic disease (9 patients), and the other type became chronic with fibrosis after repeated acute episodes (27 patients).

Results: The upper lung field was frequently involved in chronic HP (17%). Ground-glass opacities were observed in 57% and air space consolidation in 30% of the patients. Honeycombing was apparent in 37%. Twenty-six of 28 patients had antibodies to the presumptive antigens. Five of 8 patients with chronic HP were positive for antigen-induced lymphocyte proliferation. In 2 cases patients did not have detectable antibodies to causative antigens, although antigen-induced lymphocyte proliferation was detectable. The ratio of CD4 to CD8 in BAL lymphocytes was lowest in isocyanate-induced HP (mean 0.22) and tended to be high in farmer's lung and bird fancier's lung. Granulomas were observed in 39% and Masson bodies in 42% of specimens on histologic examination. Administration of prednisolone was effective in 58% of patients.

Conclusions: The insidious form of chronic HP has probably been misdiagnosed as idiopathic pulmonary fibrosis when a good history was not taken and immunologic (especially antigen-induced lymphocyte proliferation) and BAL testing were not counted.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alveolitis, Extrinsic Allergic / epidemiology*
  • Alveolitis, Extrinsic Allergic / pathology
  • Alveolitis, Extrinsic Allergic / physiopathology
  • Anti-Inflammatory Agents / therapeutic use
  • Bronchoalveolar Lavage
  • Chronic Disease
  • Female
  • Humans
  • Japan / epidemiology
  • Lung / physiopathology
  • Lymphocyte Activation / physiology
  • Male
  • Middle Aged
  • Prednisolone / therapeutic use
  • Radiography, Thoracic
  • Respiratory Function Tests
  • Tomography, X-Ray Computed


  • Anti-Inflammatory Agents
  • Prednisolone