A hygroma is a capsule filled with fluid and surrounded by a layer of fibrous tissue. Some hygromas are congenital in nature while others develop over time, usually in response to trauma. The term “hydroma” is also used to refer to a hygroma by some medical practitioners. People and animals of all agents can develop such growths, which may be benign in nature or may be associated with medical problems depending on the underlying reason the sac developed in the first place.
In the case of a congenital hygroma, errors which occur during development lead to the formation of a cyst, usually around the head or neck. Sometimes the fluid-filled sac is visible at birth and it other cases it may not be apparent until the infant has grown and the growth has grown as well. These conditions are usually not inherited, with conditions in the womb leading to the development of a hygroma. Sometimes, however, the growth is associated with chromosomal anomalies which may inherited or spontaneous in nature, in which case the patient may have other medical issues.
Hygromas caused by trauma commonly develop at the joints, such as the knees and elbows. These types of hygromas are sometimes referred to as “false bursas” because they mimic the structure of a bursa, a tough capsule which surrounds joints like the shoulder. In this case, localized swelling usually increases over time as the hygroma grows and becomes more prominent.
When a doctor identifies the swelling characteristic of a hygroma, a medical imaging study may be ordered. This is used to look inside and see what kind of material is present. The fluid accumulation is usually primarily lymph. If solids or masses appear to be present inside the hygroma, the growth may be something different and a biopsy sample may be taken in order to study the contents. The patient's history is also carefully reviewed for any relevant information.
One treatment option is sclerotherapy. This involves the injection of an agent directly into the hygroma to break it up. The contents will slowly be reabsorbed and the swelling will go down. The patient is usually much more comfortable after sclerotherapy because the growth no longer impedes freedom of movement. In other cases, it may be necessary to perform surgery to remove the sac of lymph and other materials. Doctors can discuss treatment options with their patients and make recommendations on the basis of the specifics of the case.