Hypersensitivity Pneumonitis Recognised in a Single Pulmonary Unit, between 2005 and 2015: Comparison with Recently Proposed Diagnostic Criteria

Introduction: Hypersensitivity pneumonitis (HP) is the third most common interstitial lung disease after idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia. Pathogenesis of HP is related to repeated exposure to inhaled environmental antigens that sensitise the susceptible, genetically predisposed persons. The aim of the present retrospective study was to summarise the diagnostic methods used in consecutive patients with HP, recognised in a single pulmonary unit, between 2005 and 2015, and to compare them with current diagnostic criteria. Material and methods: 135 patients, 68 males, 67 females, median age 53 years (18–75 years), entered the study. Chest CT features characteristic of HP were defined as: mosaic attenuation of lung parenchyma, air trapping and/or ill-defined centrilobular nodules. Lymphocytosis in BAL was defined as ≥30%. Results: Median time from first symptoms to diagnosis was 12 months. The exposure to one or more allergens was found in 94% of patients, chest CT features characteristic of HP have been reported in 87%, BAL lymphocytosis—in 86%. According to recent diagnostic criteria—in 54% of patients, clinical diagnosis of HP was confident, in 16%—probable, in 26%—possible and in 4%—unlikely. The confirmation of HP with lung biopsy has been obtained in 36% of non-confident cases (16% of the study group). Conclusions: HP diagnosis was confirmed according to current diagnostic criteria in 70% of patients diagnosed between 2005 and 2015. Contradictions to lung biopsy have been the main reason for inability to confirm HP in non-confident cases.