It used to be called lymphangioleiomyomatosis, a congenital abnormality in the development of lymphatic vessels. It is common in children and young adults. It occurs in the tongue, lips, cheeks, and neck, and can also be seen in the trunk and extremities. Lymphangioleiomyomata are classified into three types: macrocystic, microcystic, and mixed, depending on the size of the cystic cavity of the lymphatic vessels within the lesion. The large cystic type consists of one or more cystic cavities ≥2 cm3 in volume (i.e., cystic type or cystic hydatidiform tumor in the past), while the microcystic type consists of one or more cystic cavities 2 cm3 in volume (i.e., capillary or reticular type and spongy type in the past), and both of them are called mixed type. Clinical manifestations: The large cystic type mainly occurs in the supraclavicular region of the neck, but also in the submandibular region and the upper neck. They are usually multi-roomed cystic cavities, spaced apart from each other, and contain clear, yellowish, watery fluid. Large cystic lesions vary in size, have normal surface skin color, are filled, are soft on palpation, and have a fluctuating, translucent mass. Unlike deep venous vascular malformations, the body movement test is negative, but sometimes the transillumination test is positive. In case of intracapsular hemorrhage or infection, the tumor may show sudden enlargement and even compression of the airway leading to respiratory distress. The microcystic type consists of dilated lymphatic vessels lined with endothelial cells. The lymphatic vessels are extremely dilated and curved, forming a multi-housed cystic cavity, which resembles a sponge, and the lymphatic vessels are filled with lymphatic fluid. It presents as isolated or multiple scattered small round cystic nodular or punctate lesions on the skin or mucosa, colorless, soft, generally non-compressible, and with unclear lesion borders. Lymphatic vascular malformations of the oral mucosa sometimes coexist with microvenous malformations and appear as small yellow or red herpetiform lymphoid follicles, called lymph angiomas. If the lesions occur in the lip, submandibular and buccal areas, sometimes the affected areas may be significantly hypertrophied and deformed. If it occurs in the tongue, it often appears as megalingualism, causing malformation of the jaws, open dentition, anterior dentition, displacement of teeth, and disorder of occlusal dentition. The surface of the lingual mucosa is rough, nodular or vein-like, with small yellow blisters protruding. On the basis of long-term occurrence of chronic inflammation, the tongue may become hard. Diffuse lesions occurring in the limbs, manifesting as hyperplasia and thickening of the limb like elephant skin, also known as elephantiasis. The treatment of lymphatic duct malformation we mainly use surgery, local sclerotherapy such as urea injection can bring relief to some patients who cannot be treated surgically. Surgery is indicated especially for patients with large cystic forms. Small microcystic lesions can be completely excised; large lesions can also be excised in stages or partially excised for functional and cosmetic improvement.