What's your diagnosis? This is not a lymphoma. It's benign. Don't mind the naevus flammeus; by my knowing, it's not associated with the condition in this case. I'll post the correct answer in a few days!
Correct answer: Lynphangioma. Probably a result of aberrant growth of embryonic lymphoid tissue. It occurs sporadically. It’s benign, but it could compromise the oesophagus and trachea. Based on the picture alone, we cannot be sure what type of lymphangioma (e.g. cystic hygroma) this is, because a definitive diagnosis needs a biopsie.