Why the embryonic lymph sacs remain disconnected from the rest of the lymphatic system is also not known.Cystic lymphangioma that emerges during the first two trimesters of pregnancy is associated with genetic disorders such as Noonan syndrome and trisomies 13, 18, and 21. Chromosomal aneuploidy such as Turner syndrome or Down syndrome were found in 40% of patients with cystic hygroma. Pathophysiology
In 1976, Whimster studied the pathogenesis of lymphangioma circumscriptum, finding lymphatic cisterns in the deep subcutaneous plane are separated from the normal network of lymph vessels. They communicate with the superficial lymph vesicles through vertical, dilated lymph channels. Whimster theorized the cisterns might come from a primitive lymph sac that failed to connect with the rest of the lymphatic system during embryonic development.A thick coat of muscle fibers that cause rhythmic contractions line the sequestered primitive sacs. Rhythmic contractions increase the intramural pressure, causing dilated channels to come from the walls of the cisterns toward the skin. He suggested that the vesicles seen in lymphangioma circumscriptum are outpouchings of these dilated projecting vessels. Lymphatic and radiographic studies support Whimsters observations. Such studies reveal that big cisterns extend deeply into the skin and beyond the clinical lesions. Lymphangiomas that are deep in the dermis show no evidence of communication with the regular lymphatics. The cause for the failure of lymph sacs to connect with the lymphatic system is not known.Microscopically, the vesicles in lymphangioma circumscriptum are greatly dilated lymph channels that cause the papillary dermis to expand. They may be associated with acanthosis and hyperkeratosis.
Radiotherapy and chemical cauteries are not as effective with the lymphangioma than they are with the hemangioma. Draining lymphangiomas of fluid provides only temporary relief, so they are removed surgically. Cystic Hygroma can be treated with OK432 (Picibanil). The least invasive and most effective form of treatment is now performed by interventional radiologists. A sclerosing agent, such as 1% or 3% sodium tetradecyl sulfate, doxycycline, or ethanol, may be directly injected into a lymphocele. "All sclerosing agents are thought to work by ablating the endothelial cells of the disrupted lymphatics feeding into the lymphocele. "Lymphangioma circumscription can be healed when treated with a flashlamp pulsed dye laser, although this can cause port-wine stains and other vascular lesions.Orbital lymphangiomas, which carry significant risks from surgical removal, can also be treated with sclerosing agents, systemic medication, or through observation. Sirolimus
Sirolimus is used to treat lymphangioma . Treatment with sirolimus can decrease pain and the fullness of venous malformations, improve coagulation levels, and slow the growth of abnormal lymphatic vessels. Sirolimus is a relatively new medical therapy for the treatment of vascular malformations,   in recent years, sirolimus has emerged as a new medical treatment option for both vascular tumors and vascular malformations, as a mammalian target of rapamycin (mTOR), capable of integrating signals from the PI3K/AKT pathway to coordinate proper cell growth and proliferation. Sirolimus (rapamycin, trade name Rapamune) is a macrolide compound. It has immunosuppressant and antiproliferative functions in humans.