Hi- I am submitting this question because my boyfriend has had what looks like a clustered birthmarks over his left chest for 5 years or so. Its darker than his skin color, and probably a few inches long/wide. We have never had it looked at and I'm worried it could be something serious. He does have thyroid issues, and has pretty regular heart palpitations which we need to talk to the doctor about. He recently got a lower abdominal ultrasound/CT scan, endoscopy, and HIDA scan, because he was having some burning after he ate. They didn't find anything so they thing it's GERD. He also has pretty loose stools. He also takes anabolic steroids (I know... trying to get him to stop). Does anyone know what it could be? Worried it's some type of cancer.. also looked up angiosarcoma and am freaking out. Any advice would be very appreciated. Thank you.