Hello, My 13 yr old son has a nickel/quarter size spot on his upper back...just about an 1/8 inch to the right from his spine.  It is purplish in color much like a bruise.  It has never bothered him and it has been there for years.  Just recently it appeared raised a little, almost as if there was fluid beneath the bruise.  When I asked him once again if it hurt, he said no, in fact he could not feel anything but pressure in that area. To me the area seems bigger than it has been in the past.
Hello, I have studied your case. As per your history it looks swelling of soft tissue which can be venous clot or benign swelling. As swelling is not reducing I will advise you to further investigate for the cause of swelling. I will advise you to do MRI and Ultrasound of the swelling. If its collection or benign mass it can be excised. Bruising indicate skin infection or internal hematoma. So you may need blood investigation. Till time, you can take anti-inflammatory and antibiotic if infection is suspected. Hope this answers your query. If you have additional questions or follow-up queries then please do not hesitate in writing to us. I will be happy to answer your queries. Wishing you good health. Take care