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

Abstract

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). Conclusion: 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.

Identifying causation in hypersensitivity pneumonitis: a British perspective

“…This degree of variability is perhaps not surprising, considering the lack of a standardised national approach to establishing HP causation. While the true epidemiology of HP in Britain remains unknown, the range of estimates from the GB HP survey were broadly consistent with the findings from other studies, where the proportion of HP patients without an identifiable cause was: 0% in Japan14; 4% in Brazil15; 6% in Poland16; 28% in China17; and 25%–63% in the USA 10–13…”

“…For domestic HP, the most commonly suspected exposures are to birds, bird droppings or feathers. This is in keeping with the majority of studies from other countries, where avian exposure has been the most commonly identified cause, accounting for 17%–66% of all cases 10–12 14 16 17 24. A recent retrospective single-centred US study also noted a high prevalence of contact with avian protein in biopsy proven chronic HP cases (29% to bird and 58% to down), and incorporated a history of exposure into a prediction model 4.…”

“…Identifying exposure to a ‘known cause’ of HP remains a key element, both in the diagnostic approach for patients with unexplained ILD and in the management of confirmed HP 4–8. Despite this, the optimal approach for establishing causation remains to be determined,9 with up to 63% of cases having no identifiable aetiological agent 10–17…”

Correlation of bronchoalveolar lavage lymphocyte count with the extent of lung fibrosis and with plethysmographic lung volumes in patients with newly recognized hypersensitivity pneumonitis

“…Clinical presentation, imaging studies, and laboratory testing results of 94 patients, 49 females, 45 males, mean age 52 (±12) years, with newly recognized HP, were analyzed retrospectively. The applied diagnostic criteria of HP recognition have been described previously [13,14] and consisted of:…”

The value of serum precipitins against specific antigens in patients diagnosed with hypersensitivity pneumonitis – retrospective study

“…In case of diagnostic difficulties, the lack of exposition, non-characteristic HRCT pattern, or lack of lymphocytosis in BAL, lung biopsy was performed. The details of HP diagnostic pathway in the presented group of patients, have been described previously [11].…”