Hello,
An amelanotic melanoma will blanch on diascopy (external pressure with a glass slide). This is also true for a BCC or for any other vasular lesion. The difference between the two is absence of telangiectasia( small blood vessels running across) on amelanotic melanoma and BCCs tend to have a long history (many years sometimes) as compared to the much shorter history of a melanoma (months).
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Oh -- forgot to ask: I know that the clinical presentation of a melanoma is generally a lesion that changes (size, height, color, etc.). Can I reasonably assume that a spot/bump that remains stable over the course of months (a year...) is probably NOT a melanoma?