I have a small brownish black spot on the right side of my chest for around 2 years now . It had appeared from a small acne under the right nipple and this mark has not gone away and has remained the same size all this while . Once in a while(once a week) I do get a small pulsating feeling there like a small shock otherwise it hasn't bothered me . Is this something to worry about ? Dermatologists I've visited have told me not to bother about it so I just want to clarify with Practo experts .