Hello and welcome. When you press on skin and it turns white and then regains color after, that is called blanching. So, your concerned about this spot on your friend's back. With melanoma, they say to follow the ABCDE's. A, asymmetrical, B, border (melanoma usually doesn't have a distinct border), C, changes in color (same color over time, less likely), D, diameter (usually a quarter of an inch in diameter and grow over time), and E, evolving (changes in color, shape or size). https://www.healthline.com/health/amelanotic-melanoma#life-expectancy-and-prognosis Please do have a doctor take a look at it and let us know.