Hello, cloudiness refers to an abnormal finding in the lungs. Normally the lungs appear black because they contain air. The small airways are not apparent. The blood vessels cause some reticular whitening which is easily distinguished from abnormal patterns. When a part of the lung looses its anatomic structure cloudiness occurs. This loss of structure could be due to pneumonia (as you already pointed out), tumors, heart problems (pulmonary edema) etc. Cloudiness is not a specific finding and cannot be evaluated without clinical information and a complete description of its location and extent. Usually the patient s history is the crucial information that designates the importance of a finding. Since your brother was diagnosed with a metastatic tumor, the first thing that comes to mind is the tumor itself. Of course other - including some benign - possibilities exist. I could not be accurate without examining the x-ray and the relevant clinical information. But - to answer your main question - yes melanoma is very possible, but depending on his clinical status other etiologies are possible as well. I hope I ve addressed your concerns! If you need further information then please ask again providing an image (if possible) of the x-ray or the report and some clinical information about your brother like if he has fever, sputum, shortness of breath or any other symptom. I wish the best for him! Kind Regards!