Chronic hypersensitivity pneumonitis

Figures & data

Figure 1 Chronic HSP caused by feather pillows.

Notes: Male, 67 years of age, nonsmoker, asymptomatic, but with progressive ILD; on HRCT since 2009. Use of feather pillows for 8 years. FVC =3.02 L (70%), DLCO =12.3 mL/min/mmHg (74% of predicted). Videothoracoscopic biopsy from three lobes on the right side.
Abbreviations: HSP, hypersensitivity pneumonitis; ILD, interstitial lung disease, HRCT, high-resolution computed tomography; FVC, forced vital capacity; DLACO, diffusing capacity for carbon monoxide.

Table 1 Comparative findings between chronic nonfibrosing and fibrosing HSP (relevant exposure and two or more criteria from other separated categories are suggested as diagnostic.)

Finding	Chronic nonfibrosing HSP (“subacute”)	Chronic fibrosing HSP
Exposure/positive precipitins (Fibrosis features in HRCT Irregular linear opacities, architectural distortion, traction bronchiectasis and bronchiolectasis, lobar volume loss, honeycombing)	Presenta Absent Gound-glass opacities without findings of fibrosis is common In some cases, HRCT can be normal (air trapping on expiratory HRCT can be helpful in these cases)	Presenta Present Suggestive of HSP vs other fibrosing ILDs (one or more): 1. Ground-glass opacities > fibrosis 2. Predominant distribution in upper lobes 3. Peribronchovascular distribution 4. Relative sparing of lung basesb
Features indicative of associated or isolated bronchiolitis
Inspiratory squeaks	Occasional	Uncommon
Air trapping/mosaicc	Common	Common at expiratory HRCT
Centrilobular nodules	Common	Occasional
Airflow obstruction or increased residual volume	Occasional	Rare
Course of disease	Worsening with exposure or improvement away from exposure common	Progressive; worsening with exposure or improvement away from exposure occasional (“chronic with exacerbations”)
Lymphocytosis in BALd	Present	Absent in ∼60%
Pathology	Giant cells or granulomas in TBB or typical findings in surgical lung biopsy (sufficient for diagnosis)e	Typical findings or ACIF or NSIP or UIP

Notes:

a Can be nonapparent,

b sparing of the lung immediately adjacent to the pleura in the dorsal regions of the lower lobes or relative sparing of the lung below the level of the dome of the diaphragm,

c bilateral and present in three or more lobes,

d ≥30% in non and ex-smokers and ≥20% in current smokers,²⁰ and

e chronic bronchiolocentric inflammation, poorly formed nonnecrotizing granulomas, bronchiolitis.

Abbreviations: HSP, hypersensitivity pneumonitis; ILD, interstitial lung disease, HRCT, high-resolution computed tomography; ACIF, airway-centered interstitial fibrosis; NSIP, nonspecific interstitial pneumonia; UIP, usual interstitial pneumonia; BAL, bronchoalveolar lavage; TBB, transbronchial biopsy.

Figure 2 Chronic nonfibrotic HSP.

Notes: Female, 56 years of age, ex-smoker; dyspnea in the last 7 months. Exposure to molds in the bedroom. FVC =2.31 L (94%); FEV₁/FVC =0.87; RV =1.98 L (145%). Inspiratory HRCT without abnormalities. (A) Expiratory images showing several areas of air trapping. (B) Surgical lung biopsy showing cellular bronchiolitis with ill-defined granulomas, (C) focal peribronchiolar lymphocytic interstitial pneumonia, and air trapping. Removed from exposure with reversion of dyspnea and return of residual volume to normal range.
Abbreviations: HSP, hypersensitivity pneumonitis; HRCT, high-resolution computed tomography; FVC, forced vital capacity; RV, residual volume.

Figure 3 Chronic fibrosing HSP.

Notes: Male, 64 years of age, ex-smoker. dyspnea and cough for 2 years. Exposure to molds at home. HRCT-reticular pattern predominant in upper lobes, with peribronchovascular distribution, peripheral reticular pattern with honeycombing, asymmetric in lower lobes (A) and (B). Surgical lung biopsy-centered airway fibrosis (C) with chronic inflammatory infiltrate (D) and organizing foci in airways (E).
Abbreviations: HSP, hypersensitivity pneumonitis; HRCT, high-resolution computed tomography.

Bronchoalveolar lavage constituents in healthy individuals, idiopathic pulmonary fibrosis, and selected comparison groupsThe BAL Cooperative Group Steering CommitteeAm Rev Respir Dis19901415 pt 2S169S2022186681

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