Hi there.
His previous X-rays are not reliable in detecting lesions that are this small, and it is possible that this lesion is nothing new. However, given the work history, it is best that this lesion be seen by a specialist such as a pulmonologist, and your concern that this can be cancer has its foundations.
At this point, it is really very hard to say if this is indeed cancer, especially in the absence of other symptoms (weight loss, weakness, coughing, etc). The size of the lesion would also make diagnostic tests such as biopsy procedures to be very difficult, and we might be subjecting to patient to more harm than good. Also, the CT scan will not differentiate if this is malignant or benign. Even a PET Scan will have a hard time making conclusions in lesions this small.
From the way I see it, your pulmonologist may recommend or advise a period of observation (2-3 months) after which, he may request for another scan to see if there are any changes. If the entire family is aggressive in pursuing the diagnosis, then percutaneous biopsy (CT scan guided) or an outright operation (to remove the nodule) may be discussed (but again, there are significant risks involved).
I suggest that you discuss all of these options with your doctor when you get to meet (PET Scan, biopsy, observation, repeat CT scan, or surgery) and come up with a definitive plan. Whatever happens, I hope that everything will eventually turn out fine.
Wishing you and your brother all the best. Regards and God bless.
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