There is a difference between a lung shadow and a tumour.
Lung shadows are a technical term in imaging. There are many causes of lung shadows, including infectious diseases of the lungs in addition to lung tumours. A lung shadow is not the same as a lung tumour, and a lung tumour is not the same as lung cancer. If the lesion is not completely absorbed after treatment of a lung infection, it is possible that an inflammatory pseudotumour of the lung may form.