Journal Article

Diagnosis and Treatment of Fibrotic Hypersensitivity Pneumonia. Where We Stand and Where We Need to Go

Flaherty, Kevin R., Martinez, Fernando J., Myers, Jeffrey L., Belloli, Elizabeth A., Salisbury, Margaret L., Kazerooni, Ella A.

2017

Overview

A prospective study using consistent HRCT findings plus BAL lymphocytosis greater than 30% (or 20% for current smokers) as the \"gold standard\" criteria for HP developed a prediction rule for identifying \"active\" HP; however, the proportion of patients with radiologic/histopathologic fibrosis is not reported in this study, making use of this rule less applicable to fibrotic HP (40). The most difficult cases offibrotic lung disease to diagnose involve two scenarios: (1) there is a plausible exposure (i.e., longstanding exposure to domestic birds) but HP-associated HRCT and histopathologic findings are absent, and (2) a patient meets most of the criteria for an idiopathic interstitial pneumonia, but HRCT or biopsy shows nonspecific features sometimes associated with HP, such as mild air-trapping/mosaic attenuation on HRCT or biopsy showing rare giant cells, minor lymphocytic bronchiolitis, or airway-centered fibrosis (3). IPF is understood as a disease of aberrant wound healing after repetitive injury with upregulation of proliferation, remodeling, and myofibroblast genes, whereas inhaled antigens lead to T-cell activation and increased expression of immune response genes in HP (64-66). An animal model of pulmonary fibrosis indicates that infection with Streptococcus pneumoniae may trigger fibrosis progression, mimicking an acute disease exacerbation, with antibiotic treatment or vaccination attenuating this effect (88, 89). [...]in patients with fibrotic HP and acute disease worsening, the possibility of infection should be thoroughly evaluated and treated with appropriate antibiotics.

• Publisher: American Thoracic Society
• Subject: Acute Disease / Agreements / Algorithms / Alveolitis, Extrinsic Allergic - classification / Alveolitis, Extrinsic Allergic - diagnosis / Alveolitis, Extrinsic Allergic - pathology / Alveolitis, Extrinsic Allergic - therapy / Antibiotics / Antigens / Biopsy / Bronchoscopy / Chronic Disease / Classification / Diagnostic tests / Humans / Immunosuppressive Agents - therapeutic use / Lung diseases / Lung Transplantation / Medical diagnosis / Medical prognosis / Mortality / Pneumonia / Pulmonary fibrosis / Pulmonary Fibrosis - classification / Pulmonary Fibrosis - diagnosis / Pulmonary Fibrosis - pathology / Pulmonary Fibrosis - therapy / Pulmonary s / Respiratory Therapy / Streptococcus infections / Tomography / Tomography, X-Ray Computed