Smoking related interstitial fibrosis – a new entity Leonor Meira1, Rita Boaventura1, Natália Melo1, Patrícia Caetano Mota1,2, José Miguel Pereira3, Susana Guimarães4, Conceição Souto Moura4, António Morais1,2 1 Pulmonology Department, Centro Hospitalar de São João, Oporto, Portugal 2 Faculdade de Medicina da Universidade do Porto, 3 Radiology Department, Centro Hospitalar de São João, Oporto, Portugal 4 Pathology Department, Centro Hospitalar de São João, Oporto, Portugal INTRODUTION: Smoking has been implicated in multiple interstitial lung diseases (ILD), such as desquamative interstitial pneumonia (DIP) or respiratory bronchiolitis-associated interstitial lung disease (RB-ILD).Smoking related interstitial fibrosis (SRIF) is a recently described entity, characterized by a distinct form of hyalinized interstitial fibrosis associated with emphysema and respiratory bronchiolitis. The diagnosis is often done accidentally, through pulmonary parenchyma samples obtained for other purposes, and usually is not associated with significant respiratory symptoms. Functionally these patients may present obstruction and mild to moderate decrease DLCO. The most typical radiological findings in chest HRCT are well delimited subpleural foci of emphysema, predominantly in middle and upper regions, associated with ground-glass opacities and reticulation. The authors describe three cases of patients diagnosed with SRIF. Case 1 Case 2 Case 3 ID: ♂, 60 years old, works in pavement replacement Previous clinical history: Urothelial carcinoma, type two diabetes mellitus, arterial hypertension, smoker (70 pack years) Exposures: occasional exposure to birds Symptoms: dry cough and blood-streaked sputum HR CT of lung: “(…) ground glass opacities in the periphery, mainly in the upper lobes ” Lung function: FVC 122.1%; FEV1 106.2%; IT 68.96%, DLCO 50% ID: ♂, 49 years old, car mechanic Previous clinical history: smoker (50 pack years), type two diabetes mellitus Exposures: paints and solvents Symptoms: mucous sputum HR CT of lung: “(…) micronodules and bilateral ground glass opacities ” Lung function: FVC 85.3%; FEV1 88.7%; IT 81.65%; DLCO 65.2% ID: ♂, 53 years old, construction worker Previous clinical history: Chronic bronchitis, smoker (37 pack years) Exposures: coal and gold mines Symptoms: mild cough HR CT of lung: “Panlobular and parasseptal emphysema, mainly in the upper lobes (…) ground glass opacities in the periphery” Lung function: FVC 122.5%; FEV1 122.2%; IT 80.68%; DLCO 66% Suspicious DIP Suspicious NSIP Suspicious RB-ILD/ DIP Cryobiopsy upper and lower right bronchus Cryobiopsy lower left bronchus Cryobiopsy upper right bronchus BAL (%) Macroph. 71,4 Lymph. 4,2 Neut. 11,8 Eosi. 9,4 BAL (%) Macroph. 80,8 Lymph. 10,8 Neut. 4,4 Eosi. 1,2 BAL (%) Macroph. 96,4 Lymph. 2 Neut. 0,2 Eosi. 1,4 “uniform thickening of alveolar septa by hyalinized collagen fibrosis and intra-alveolar pigmented macrophages with finely granular golden-brown pigment: RB-ILD/DIP features and hyalinized interstitial fibrosis – SRIF” “alveolar septa thickening, with moderate hyalinized fibrosis (…) and airspaces with aggregates of macrophages with finely granular golden-brown pigment: RB-ILD/DIP features and hyalinized interstitial fibrosis – SRIF “ Intra-alveolar macrophages with granular golden-brown pigment (…) interstitial hyalinized fibrosis, with mild inflammatory infiltrate : RB-ILD/DIP features and hyalinized interstitial fibrosis – SRIF” DISCUSSION: With the presentation of these cases, the authors wish to demonstrate the importance of an accurate diagnosis of smoking related ILD, owing to variable pathophysiology and prognosis. The patients described are clinically stable and under regular follow up, but the natural history of SIRF is still unknown, given its recent description.