CT findings in biomass smoke-associated interstitial lung disease: A retrospective analysis.

Objectives: Household air pollution from biomass fuel combustion remains a major global health burden, affecting nearly 3 billion people worldwide. Although biomass smoke exposure is a recognized risk factor for chronic airway disease, its role in interstitial lung disease (ILD) is less well defined, and characteristic CT features have not been systematically described in patients without coexisting chronic obstructive pulmonary disease (COPD). Material and Methods: We conducted a retrospective review of 23 patients with biomass smoke exposure and radiographic evidence of ILD, excluding those with alternative ILD etiologies or pre-existing COPD. CT scans were independently assessed by a thoracic radiologist and two pulmonologists for predominant patterns, distributions, and additional findings, with consensus classification. We report proportions with 95% confidence intervals (CIs) and performed exploratory Spearman correlation to assess associations between selected CT features. Results: The cohort (mean age 71.7 years; all females; 96% born outside the United States) most commonly demonstrated reticulation (16/23, 70%; 95% CI, 49-84%), ground-glass opacities (GGO) (15/23, 65%; 95% CI, 45-81%), mosaic attenuation (15/23, 65%; 95% CI, 45-81%), and bronchial wall thickening (14/23, 61%; 95% CI, 41-78%). Abnormalities were typically patchy (18/23, 78%; 95% CI, 58-90%) and peribronchial (13/23, 57%; 95% CI, 37-74%), without consistent apical or basal predominance. Traction bronchiectasis occurred in 12/23 (52%; 95% CI, 33-71%) and lymphadenopathy in 9/23 (39%; 95% CI, 22-59%). Honeycombing (5/23, 22%; 95% CI, 10-42%), centrilobular emphysema (4/23, 17%; 95% CI, 7-37%), nodules (3/23, 13%; 95% CI, 5-32%), cysts (2/23, 9%; 95% CI, 2-27%), tree-in-bud opacities (2/23, 9%; 95% CI, 2-27%), and centrilobular nodularity (1/23, 4%; 95% CI, 1-21%) were uncommon. Exploratory Spearman analyses showed strong associations between mosaic attenuation and bronchial wall thickening (ρ = 0.91) and between peribronchial distribution and mosaic attenuation (ρ = 0.83), with additional positive correlations between mosaic attenuation and bronchiectasis (ρ = 0.70), peribronchial distribution and bronchial wall thickening (ρ = 0.73), bronchial wall thickening and bronchiectasis (ρ = 0.77), bronchiectasis and traction bronchiectasis (ρ = 0.57), and reticulation and traction bronchiectasis (ρ = 0.69). Exploratory Spearman correlation analyses showed strong associations between mosaic attenuation and bronchial wall thickening (ρ = 0.91) and between peribronchial distribution and mosaic attenuation (ρ = 0.83), with additional positive correlations between mosaic attenuation and bronchiectasis (ρ = 0.70), peribronchial distribution and bronchial wall thickening (ρ = 0.73), bronchial wall thickening and bronchiectasis (ρ = 0.77), bronchiectasis and traction bronchiectasis (ρ = 0.57), and reticulation and traction bronchiectasis (ρ = 0.69). Conclusion: Biomass smoke-associated ILD demonstrates a distinctive CT pattern characterized by reticulation, GGOs, and mosaic attenuation with patchy and peribronchial distribution and no clear zonal predominance. Unlike hypersensitivity pneumonitis, it lacks centrilobular nodularity. Compared with idiopathic pulmonary fibrosis (IPF), it shows less extensive subpleural honeycombing, more peribronchial involvement, and no consistent basal predominance. These distinctions may improve recognition of biomass smoke-associated ILD in exposed patients. Further prospective studies are needed to validate these findings and clarify their prognostic significance.