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Lymphangiomas are malformations of the lymphatic system characterized by lesions that are thin-walled cysts; these cysts can be macroscopic, as in a cystic hygroma, or microscopic. The lymphatic system is the network of vessels responsible for returning to the venous system excess fluid from tissues as well as the lymph nodes that filter this fluid for signs of pathogens. These malformations can occur at any age and may involve any part of the body, but 90% occur in children less than 2 years of age and involve the head and neck. These malformations are either congenital or acquired. Congenital lymphangiomas are often associated with chromosomal abnormalities such as Turner syndrome, although they can also exist in isolation. Lymphangiomas are commonly diagnosed before birth using fetal ultrasonography. Acquired lymphangiomas may result from trauma, inflammation, or lymphatic obstruction. Most lymphangiomas are benign lesions that result only in a soft, slow-growing, "doughy" mass. Since they have no chance of becoming malignant, lymphangiomas are usually treated for cosmetic reasons only. Rarely, impingement upon critical organs may result in complications, such as respiratory distress when a lymphangioma compresses the airway. Treatment includes aspiration, surgical excision, laser and radiofrequency ablation, and sclerotherapy. ==Classification== Lymphangiomas have traditionally been classified into three subtypes: ''capillary'' and ''cavernous lymphangiomas'' and cystic hygroma. This classification is based on their microscopic characteristics. A fourth subtype, the ''hemangiolymphangioma'' is also recognized. ;Capillary lymphangiomas :Capillary lymphangiomas are composed of small, capillary-sized lymphatic vessels and are characteristically located in the epidermis. ;Cavernous lymphangiomas :Composed of dilated lymphatic channels, cavernous lymphangiomas characteristically invade surrounding tissues. ;Cystic hygromas :Cystic hygromas are large, macrocystic lymphangiomas filled with straw-colored, protein-rich fluid. ;Hemangiolymphangioma :As suggested by their name, hemangiolymphangiomas are lymphangiomas with a vascular component. Lymphangiomas may also be classified into ''microcystic'', ''macrocystic'', and ''mixed'' subtypes, according to the size of their cysts.〔 ;Microcystic lymphangiomas :Microcystic lymphangiomas are composed of cysts, each of which measures less than 2 cm3 in volume. ;Macrocystic lymphangiomas :Macrocystic lymphangiomas contain cysts measuring more than 2 cm3 in volume. ;Mixed lymphangiomas :Lymphangiomas of the mixed type contain both microcystic and macrocystic components. Finally, lymphangiomas may be described in stages, which vary by location and extent of disease. In particular, stage depends on whether lymphangiomas are present above or ''superior'' to the hyoid bone (''suprahyoid''), below or ''inferior'' to the hyoid bone (''infrahyoid''), and whether the lymphangiomas are on one side of the body (''unilateral'') or both (''bilateral'').〔 ;Stage I: Unilateral infrahyoid. ;Stage II: Unilateral suprahyoid. ;Stage III: Unilateral suprahyoid and infrahyoid. ;Stage IV: Bilateral suprahyoid. ;Stage V: Bilateral suprahyoid and infrahyoid. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lymphangioma」の詳細全文を読む スポンサード リンク
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