What is the medical term for a tumor composed of lymph vessels?

Lymph vessel tumor. Lymphangioma is the term for a tumor composed of lymphatic vessels; there are 3 types: capillary, cavernous, & cystic hygroma. 50% are present at birth, 90% by age 2 yrs; a rare tumor that accounts for 4% of vascular tumors in children. [the annals of otology, rhinology, and laryngology 111 (12 pt 1): 1066–75. & lymphangioma at emedicine].