I have a case of seborrheic keratosis. Before you exclaim "you filthy beast!" or "serves you right", it's another way of saying what looks like a mole suddenly appeared one day, but it's all right, the condition is benign and temporary. It's also part of growing old, which sadly isn't temporary and invariably fatal, but that's the long-term prognosis.
I discovered the mole simply by scratching my abdomen one day and there it was, with a slight drop of blood where my nail caught it. "It's been traumatised," said the doctor examining it. Well, I'm sorry but how did it think I felt? And I refuse to apologise to uninvited guests on my skin.
So, could be worse, as this guy could attest:
Fulminant acute colitis following a self-administered hydrofluoric acid enema.