Surely, a thoracic surgeon must know if a round spot is a lung nodule, carcinoid or a coin lesion by looking at pet, ct and x-rays. yes or no?

Pathology specimen: The pathologist makes the diagnosis with the microscopic exam of a piece of the lesion. Even then, it can be challenging to get diagnosis. So the answer to your question is no. Stay with your thoracic surgeon, get your follow up exams, stop nicotine if you have that addiction. Ok to go for a second opinion. Take a friend with you and don't be surprised if you get same answer.

Concur: As drberg has responded, definitive diagnosis requires tissue analysis by pathologist. Radiographic imaging ct scans, pet scans, mri, chest xray, etc... May identify an abnormality. The features on the film may be suggestive of a particular pathology. However, that is not diagnostic.

Need a tissue sample: Although imaging can provide a differential diagnosis, or list of probable diseases, it often requires a biopsy of the lesion and review of the actual tissue under a microscope by a pathologist to make the final diagnosis. No one wants to get the wrong treatment, so the disease must be confirmed so that inappropriate treatment is not started.