Posterior pharyngeal Lymphatic hypertrophy. If no symptoms then why did you take the photo? Feeling of a lump in throat or like something you can't swallow properly. It might be a part of some viral infection recently. All of these symptoms come down significantly after you reach adulthood.
Next Steps
1. If you don't have any symptoms nothing to do.
2. If discomfort can Gargle with warm saline water 4-5 times daily and you'll feel better.
Health Tips
Feel free to consult me or any physician if you have any other queries or symptoms.