Brief Answer:
Enlarged ,wider vein.

Detailed Answer:
Hello dear, welcome to ask a doctor's service .
I read your query and here is my advice.
I see the photos you attached and it is an enlarged vein in the throat mucosa near one of your tonsils.
It looks like an enlarged or varicose vein not a cyst because cysts are usually white filled with mucus.
The lesion you refer is filed with blood a wide vein filled with blood.
I don't think this can be dangerous or something to worry about. Nothing should be done.

Hope I have answered the question.
Let me know if I am can assist you further.

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