Wondering how rare it is for melanoma tumors like mine to happen--I saw mine when it was removed, and it looked like my little pinkie in shape, and was 6.5mm in depth and about 2-1/2 inches sideways in width located on my back--it had grown underneath the skin with nothing on top showing. It had already metastasized to one underarm lymph node and was diagnosed as Stage 3B. All of the photos of melanoma I see on the internet have a colored spot on top of the skin and under the skin looks like tree trunk with roots. PLEASE let me hear from you if you had a sideways (horizontal) growing melanoma tumor. THANKS!!!!