It is difficult to know from your question what exactly is going on, and without seeing the imaging and knowing your father's history I can't really say whether your dad's imaging is suggestive of malignancy. So it is important for you to speak with your father's doctors
. It is also a little unclear to me what kind of imaging you're talking about; lesions on a chest x-ray are very different than lesions on a CT scan, which tends to provide a lot more information. Lesion is also a fairly non-specific word, and most likely means that the imaging shows an abnormality but it is not clear from the imaging what that abnormality is. That being said, abnormalities on imaging arise from something filling
the airspace, which can be abnormal cells (tumor), pus (pneumonia
), water (pulmonary edema) or blood. There can also be imaging changes from abnormalities outside the lung, such as an empyema or a pleural effusion. All of this is to say that, without seeing the imaging or knowing the case, there are many different possibility for abnormalities on imaging, and the symptoms of cough and pain could also be due to many things, not limited to cancer. This is definitely the kind of issue where you need to stay in close communication with your father's doctors and discuss what the possibilities that they're thinking of and what the next steps should be.