Any experience with Bone Cysts?

[QuintessentialShadow]

My 11 year old son complains about pain in his knee, when walking/cycling, generally being active.

He has a round hard lump of bone on his knee, and the area around is sore.
He has an appointment with his GP monday, but I am just worried that this is something to really worry about.

Google is not my friend.
I now worry that he has bone cancer.

Is the lump below his kneecap? It could be osgood-schlatters disease, common in active teens and usually resolves itself.

As mentioned above osgood schlatters develops around this age, and one sign is a bony lump. Is he very tall for his age/had a sudden growth spurt?

It is slightly left and above center of his knee.

He is tall for his age, he is very active. He plays football at every break time in school, and handball twice a week. He also cycles and plays football for fun.He has had a very active summer.
This summer he has been on a wilderness camp, followed by paddlesports camp and then a week of kayaking. He has been three times to the climbing wall in the last week, and cycled 30 km each weekend. He is bursting with energy.

I will google osgood schlatter. Thanks!

Ok, that was reassuring reading.
He loves jumping, and he loves the trampoline, and he has been doing gymnastics since he was 6, but having a break this year. Seems Osgood schlatter is more likely than other things google came up with.