Overlaps and uncertainties of smoking-related idiopathic interstitial pneumonias

Figures & data

Figure 1 A 45-year-old male smoker with pathologically diagnosed RB.

Notes: An axial CT image at the level of the aortic arch shows poorly defined bilateral centrilobular nodules (black arrows) reflecting the accumulation of smoker’s macrophages. Image courtesy of Samsung Medical Center.
Abbreviations: CT, computed tomography; RB, respiratory bronchiolitis.

Table 1 Summary of key features

Characteristics	RB/RB-ILD	DIP
Incidence according to sex	M = F	M > F
Clinical features	Chronic cough	Chronic cough with bilateral crackles
	Inspiratory crackles	Digital clubbing (~50%)
PFTs	Normal or mixed restrictive–obstructive pattern	Restrictive pattern
	Decreased DLco	Reduction in DLco
Bronchoalveolar lavage	Increased macrophages	Increased macrophages
	Modest increase in neutrophils	Mild increase in the percentage of eosinophil and neutrophil cells
Key histopathological finding	Pigmented macrophages in the respiratory bronchioles	Diffuse and uniform, filled with pigmented macrophages
Radiological findings	Centrilobular nodules and GGOs, predominantly in the upper and middle lobes	Diffuse GGOs, predominantly lower and subpleural
	Mild interlobular septal thickening
Spontaneous improvement	Possible	Occasionally
Treatment	Smoking cessation	Smoking cessation and steroid

Abbreviations: DIP, desquamative interstitial pneumonia; DLco, diffusing capacity of the lung for carbon monoxide; F, female; GGO, ground-glass opacity; ILD, interstitial lung disease; M, male; PFT, pulmonary function test; RB, respiratory bronchiolitis.

Figure 2 A 57-year-old male smoker with pathologically diagnosed DIP.

Notes: The axial CT image shows GGO in a subpleural and lower distribution. Thin-walled cysts (black arrows) are seen within the region of the GGOs. Image courtesy of Samsung Medical Center.

Abbreviations: CT, computed tomography; DIP, desquamative interstitial pneumonia; GGO, ground-glass opacity.

Figure 3 CT features of AEF.

Notes: (A) A 70-year-old male smoker (50 pack-years) showing up to 10 mm sized multiple thick-walled areas (black arrow) of centrilobular and paraseptal emphysema. (B) A 70-year-old male ex-smoker (72 pack-years) showing up to 25 mm sized multiple thick-walled area (black arrows) of centrilobular and paraseptal emphysema. Image courtesy of Samsung Medical Center.
Abbreviations: AEF, airspace enlargement with fibrosis; CT, computed tomography.

Figure 4 A 26-year-old male ex-smoker with pathologically diagnosed RB.

Notes: (A) Initial chest CT revealed bilateral and symmetric bizarre-shaped cysts and nodules with an upper zone predominant distribution and sparing of the costophrenic angles. (B) After 136 months, there was an increase in the extent of nodules in both lungs after the patient had resumed smoking. The lesions markedly decreased after smoking cessation on follow-up chest radiography. Image courtesy of Samsung Medical Center.
Abbreviations: CT, computed tomography; RB, respiratory bronchiolitis.

Figure 5 A 66-year-old male ex-smoker with lung biopsy-proven RB-ILD.

Notes: There were bronchiolocentric GGOs and traction bronchiectasis in both lungs that represented airway-centered interstitial fibrosis. Image courtesy of Samsung Medical Center.

Abbreviations: GGO, ground-glass opacity; ILD, interstitial lung disease; RB, respiratory bronchiolitis.

Figure 6 A 44-year-old male smoker with pathologically diagnosed RB-ILD.

Notes: (A) Initial chest CT examinations revealed subpleural GGO in the middle and lower zones and centrilobular GGOs and emphysema in the upper lobes. Ill-defined centrilobular GGOs were considered findings of RB that reflected the accumulation of smoker’s macrophages. (B) After 31 months, there was a slight increase in the extent of GGOs in both lungs. (C and D) Findings of GGOs, reticulation, honeycombing, and bronchiectasis were increased at both 111 and 162 months postoperatively. There was also evidence of a typical UIP pattern. Image courtesy of Samsung Medical Center.
Abbreviations: CT, computed tomography; GGO, ground-glass opacity; ILD, interstitial lung disease; RB, respiratory bronchiolitis; UIP, usual interstitial pneumonia.