Hi , I am brandon and I am 20 years old. Some time ago I found a small round ball on the lower of my butt. After about 6 months I noticed it got bigger.  About 5 years ago i was diagnosed with a giant cell tumor on the lower part of my back. Can this be a cyst or a tumor ?
Welcome at Chat Doctor I appreciate your health concerns.  Based upon the history provided, it is difficult to comment. In my opinion the lump need to be examined for clinical conclusion. It should be looked for the size, consistency, overlying skin and Chat Doctor.  After then, we can proceed further.  Biopsy will confirm the diagnosis, but it should only be performed after clinical examination.  Meet your surgeon Hope it helps Regards