Introduction: Interstitial lung disease (ILD) is known as a pulmonary pathology grouping a set of heterogeneous lung diseases. The aim of this study was to determine the prevalence of ILD predominant in the upper lobes their etiologies, clinical characteristics and prognosis.

Methods: A retrospective comparative study was performed between 2011 and 2022 in pneumology department 1, of the Abderrahmane Mami hospital in Tunisia. We included patients followed for ILD.Our patients were divided into two groups:

Group1(G1): patients with upper lobe involvement on chest CT

Group2(G2): patients with non-upper lobe involvement on chest CT

Results : One hundred and nine patients were included. G1:26 patients and G2:83 patients. Compared to G2, G1 were younger (57.62 years vs 63.30 years; p=0.05). At bronchoalveolar lavage G1 had more hyper eosinophilia (50% vs 27.7%; p=0.03) and more hyperlymphocytosis (42.3% vs 34.9%; p=0.4). On chest CT, G1 had more condensation (57.7% vs 25.3%; p=0.002), more nodules (53.8% vs 26.5%; p=0.01) and less honeycomb (26.9% vs 49.4%; p=0.04). Ground glass (p=0.8), thickening of septal lines (p=0.6) were similar between the two groups. Etiologies retained were respectively: sarcoidosis (G1:58.3% vs. G2:12.5%; p<0.001); hypersensitivity pneumonitis (G1:8% vs G2:0%; p=0.009), UIP (G1:4.2% vs G2:22.5%; p=0.004). Seventy percent of G1 patients have had corticotherapy versus 24.4% of G2 (p<0.001). Long-term oxygen use was similar in both groups (p=0,8). Average survival was (G1: 4,04 vs G2: 2,65 years; p<0.001).

Conclusion: ILD with upper lobe involvement is more associated with sarcoidosis and hypersensitivity pneumonitis; frequent use of corticotherapy and better prognosis.