I do not want to alarm you but you really need to see someone else. How was the lesion biopsied...shave, punch, incision? I understand your derm sending you to a plastic surgeon because of where it was - on your face, however you really need a melanoma specialist or a derm who specializes in melanoma. A 'thin' melanoma is good - I have never heard a lesion referred to as 'intermediate' - they usually stage a thin one as stage one or in-situ. If indeed it was under a certain mm. they usually do not do a biopsy of the lymph nodes.
My son was diagnosed with stage 3 and recently went through the sugery to remove lymph nodes. His chest x ray remains clear.
So what I am saying is that a clear chest x ray does not guarantee the stage of your melanoma.
Ask the plastic surgeon's office what depth your lesion measured.
You can read more about this on several places on the net. NCI has good site that explains how these things are staged.
My best to you - feel free to contact me and/or go to www.mpip.org for a message board that is more active than here. However, do not let it scare you - it is somewhat lopsided with people who are in later stages than you seem to be.
Mrs. C