The presence of a mass lesion in a patient with established pulmonary fibrosis is strongly suspicious for a primary lung carcinoma.

In this patient, because of the severity of symptoms, it was decided not to submit him to a lung biopsy or any medical or surgical treatment.

Idiopathic pulmonary fibrosis (IPF) is the histological or imaging pattern of usual interstitial pneumonia (UIP) and has no alternative causes such as drug toxicity, environmental exposure (e.g. asbestos) or collagen vascular disease (e.g. scleroderma, rheumatoid arthritis) to justify its occurrence. 

On CT, usually it has the following features:

• peripheral reticulation, predominantly in bases
• honeycomb pattern
• ground-glass opacities (less extensive than reticulation)
• architectural distortion with traction bronchiectasis or bronchiolectasis

Approximately 10% of patients with IPF develop lung cancer (commonly adenocarcinoma and squamous cell carcinomas), and, due to their clinical status related to the pulmonary fibrosis, a large number of them can not be submitted to surgery.