I agree with Alice. Sunburn or bruising for the blackening area. If it is dry and brittle, I wouldn't worry. If it is soft, remove the tissue >1cm from the black edge using a sterile blade, dust the cut edge with powdered cinnamon.
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Anon Y Mouse
"Never attribute to malice that which is adequately explained by stupidity." Hanlon’s Razor
I am not being argumentative. I am correcting you!