Brief Answer:
It can be benign tonsillar growth

Detailed Answer:
Hello

Thanks for asking on this platform

I can understand your concern.
I have gone through the image.There is enlargement of right tonsil which is extending almost to the midline.
As it is present since birth and dies not causes any difficulty ,infection which is the most common cause is ruled out(not likely).
There are few condition like congenital lymphangioma of tonsil or other benign growth of the tonsil which I would like to rule out.Most of this swelling remain asymptomatic unless it over grows and causes swallowing or breathing difficulty.
I would like to get him evaluated by an ENT specialist and biopsy of the growth may be needed to confirm the diagnosis.

I hope this helps.
Please let me know if you have any more query.
Regards

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