Both lymphangioma and branchial cyst are lateral neck masses. Branchial cysts are not translucent whereas lymphangioma when subjected to light test is brilliantly translucent.
Lymphangiomas
Lymphangiomas are uncommon, hamartomatous, congenital malformations of the lymphatic system that involve the skin and subcutaneous tissues. It occurs as a result of sequestration or obstruction of developing lymph vessels in approximately 1 in 12,000 births. Lymphangiomas can occur anywhere in the skin and the mucous membranes. The most common sites are the head and the neck especially in the posterior triangle of the neck. The cysts are lined by endothelium and filled with lymph.
Occasionally unilocular cysts occur, but more often there are multiple cysts infiltrating the surrounding structures and distorting the local anatomy. The mass may be apparent at birth or may appear and enlarge rapidly in the early weeks or months of life as lymph accumulates; most present by age 2 years. (90% of lymphangioma occur in children less than 2 years) Lymphangiomas are soft and nontender and when subjected to light test was brilliantly translucent.