Lymphangioma refers to a rare, congenital condition that usually does not pose a health threat unless it occurs in a fetus. Lymphangiomas occur when a blockage in the lymphic system leads to fluid accumulation, and they typically appear as a fluid-filled, yellowish or reddish bubble or series of bubbles beneath the skin.​
They are mainly seen in children under the age of two and many are diagnosed in the womb. Although they can occur anywhere in the body, about 90% are found in the head and neck. They present as a mass and are benign. If they are removed it is usually done for cosmetic reasons as they rarely pose any medical threats. 
Types of lymphangioma include - Capillary lymphangioma – These are made up of small lymphatic vessels found in the epidermis.​
Cystic Lymphangioma – These are large masses filled with liquid.​
Cavernous lymphangioma – Cavernous lymphangioma are comprised of dilated lymphatic channels. They can invade the tissues around them.​
Signs and SymptomsCapillary lymphangioma consists of one or a cluster of translucent, bubble-like structures of varying sizes on the surface of the skin. They are typically pink to dark red in color.​
Cavernous lymphaniomas vary widely in size, ranging from as small as a centimeter in diameter to several centimeters wide. In some cases, they may even affect an entire extremity such as a hand or foot. Although they are usually painless, the patient may feel mild pain when pressure is exerted on the area.
​Cystic lymphangiomas usually have a softer consistency than cavernous lymphaniomas, and this term is typically the one that is applied to lymphangiomas that develop in fetuses. 
Causes and Risk FactorsThe direct cause of lymphangioma is a blockage of the lymphatic system as a fetus develops, although symptoms may not become visible until after the baby is born. This blockage, in turn, is thought to be caused by a number of factors, including maternal alcohol use and viral infections during pregnancy.
​Diagnosis and TreatmentAs mentioned, lymphangioma can be detected using ultrasound. Other than looking at the cells under a microscope there is no test that can be done to accurately diagnose lymphangioma. An MRI is sometimes helpful in showing the extent of the growth of a lymphangioma.
​TreatmentThe most effective treatment for lymphangioma is complete surgical removal. This is rarely possible without having to also remove some surrounding healthy tissue and for this reason lymphangioma often have a high rate of recurrence. However, since they are benign, prognosis is generally excellent.