Miley Cyrus -- The Return of the Mysterious Scratch Marks

It's been a few months since Miley Cyrus denied having a self-mutilation problem -- but today in L.A., the singer surfaced with several ominous-looking scrapes on her left forearm.

Back in April, Miley sported similar marks on her arm, causing a firestorm of speculation that the singer had been harming herself.

Miley responded to the rumors, insisting she does NOT self-mutilate ... but she never explained what caused the mystery marks. Now, they've suddenly returned.