Classified as a differentiated lymphangioblastic tumor, lymphangioma is actually a benign angioblastic tumor, consisting of vasal spaces lined by endothelium, just like in more common angiomas, but differing in that they contain lymph or chyle (chylous angioma). Lymphangiomas are classified by the size of these vasal spaces into: simple lymphangioma, cavernous lymphangioma (with larger spaces), and cystic lymphangioma or hygroma (congenital hamartoma, similar to cavernous lymphangioma, with typical localizations, near embryonic lymph sacs).