Fibrosing lung diseases represent a heterogeneous group of interstitial lung diseases (ILD) characterised by radiological signs of fibrosis with a progressive course in 13—40% of cases. Lung fibrosis can be associated with lung cancer, significantly impacting disease survival. Persistent pulmonary fibrosis increases a patient’s risk of developing lung cancer. Progressive pulmonary fibrosis (PPF) and lung cancer share common molecular genetic links and risk factors including male gender, smoking, occupational/environmental exposures, low pulmonary function and rapid annual decline in forced vital capacity. Clinical studies confirm that in 75.5% of patients with usual interstitial pneumonia (UIP), lung cancer is found in the subpleural areas of the lower lobes, which corresponds to the typical distribution of fibrotic changes in UIP. Whereas, in patients with other ILD and histology lung cancer is mainly (68.1%) located in the upper lobes. The present observation of chronic hypersensitivity pneumonitis (CHP) with PPF is a clinical illustration confirming the relationship between fibrosing CHP and lung cancer. The difficulties of early diagnosis are due to the unspecific of the clinical and radiological features, which may be a manifestation of both the progression of fibrosing lung disease and the development of lung cancer. Lung cancer is one of the most frequent comorbidities in patients with PPF and requires early diagnosis.