Injection sclerotherapy with bleomycin is a very good option and u will be surprise to see the results. large lymphnagiomas are not easy to remove completely and there is lots of morbidity associated with it.
I agree with you, we have to try medical treatment 1st, as only 40% of CH can be completely excised so the recurrence rate is high, Using OK 432 which is inactive group A Streptococcus pyogens can give success rate of 60-100%.
If there is not an important morbidity for the infant at the moment, do not hurry for surgical intervention. %6 of lymphangiomas can regress spontaneously. We had such a case.
Proper imaging the patient is important to determine if this is a pure lymphangioma or does it have a venous component. Is there extension into the chest. If it is asymptomatic then there is no urgency to treatment. Sclerotherapy by someone with experience would be the best management.