Hi, Thanks for writing in. If your father is experiencing intermittent fever and CT scan shows an even mass 5 cms in the lungs, the suspicion points mores towards a lung abscess. Cough and tiny amount of blood are also seen in patients with lung abscesses. It would be important to aspirate material from the mass under CT scan guidance and send it for pathology and microbiology evaluation. This will tell us the exact nature of any bacteria if present and what medications to give. Cancerous mass will come only if the aspirate shows cancer cells. It is less likely because cancer usually show irregular masses with aggressive involvement. Cancers also show multiple masses in many patients. However because of history of bladder cancer in the past, cancer cannot be totally ruled out. Please get the FNAC/ biopsy done at earliest and begin treatment for his condition. Hope this helps