Osgood Schlatter vs Osteosarcoma

Hi,
I recently took my 12 year old son to the pediatrician for what I thought was Osgood Schlatter Disease. I had googled his symptoms and was sure this is what he has. But the pediatrician said that Osgood Schlatter is more involved near the ligament below the knee that connects to the libia and that my son's was a bony growth on his bone just below this area. His symptoms are pain with actitivies, pain at night, and sometimes he limps. It is slightly swollen around the growth but is not hot to touch and he says that it does not hurt when pressure is applied and that is a general dull ache in the area but not directly on the bump. The pain has been increasing weekly.
The pediatrician said he had to check into this further. He ordered an x-ray and blood tests for ESR, CRP, and ALP levels along with a CBC. I have since googled these blood tests and what they are used for and I found that they are used to look for inflammation and also for Osteosarcoma. I was really surprised at the similiarities between the two different conditions, one benign and the other very serious. Is there anything that distinguishes them that can be seen with the eye to give me some peace of mind until all the test results come back? Have you ever come across Osgood Schlatter that has a bony growth below the area of the ligament? The growth is egg shaped and is about 1 inch wide by 2 inches long. Thank you

[Michael L Gross, MD]

Those are all general tests, and in reality, might be used to rule out almost anything, not osteosarcoma.  From what you have described, this still sounds like Osgood Schlatters disease to me.  As I'm sure you know, Osgood Schlatters disease is a benign irritation of the attachment site for the patella tendon.  It occurs in children because that area is made of uncalcified cartilage and is a result of overuse.  Osgood Schlatters is part of a group of common overuse injuries in children known as osteochondroses.

[stevie_wonder]

Sorry that should read "tibia" not "libia".