A cystic hygroma is a benign, fluid-filled sac resulting from a malformation of the lymphatic system. These sacs are congenital, meaning they are present at birth, and are characterized by their soft, compressible nature.
Understanding Cystic Hygromas
Cystic hygromas are lymphatic malformations that develop during fetal growth. These malformations cause lymphatic fluid to accumulate, forming one or more cysts. They often appear as a soft, compressible mass under the skin.
These growths commonly appear in the neck, which is the most frequent location. Other common sites include the armpit, groin, and less often, the trunk or internal organs. Their size can range from a small lump to a large mass that affects surrounding structures.
Cystic hygromas are categorized into two main types: macrocystic and microcystic. Macrocystic hygromas consist of one or a few large, clearly defined cysts. In contrast, microcystic hygromas are composed of numerous small, diffuse cysts that can infiltrate surrounding tissues, making them more challenging to treat. Their size or location can lead to complications such as breathing difficulties, swallowing issues, or cosmetic concerns.
Causes and Associated Conditions
Cystic hygromas form due to an error in the lymphatic system’s development during early fetal stages, typically between the 9th and 16th weeks of gestation. Lymphatic vessels drain excess fluid from tissues; if they fail to connect properly to the venous system, fluid accumulates and forms cysts.
While many cases arise spontaneously with no clear genetic link, some are associated with specific chromosomal abnormalities. Conditions like Turner syndrome, Down syndrome (trisomy 21), Trisomy 13, and Trisomy 18 have a higher incidence of cystic hygromas.
The presence of a cystic hygroma does not automatically imply a chromosomal abnormality. In many cases, the exact cause remains unknown, and the child is otherwise chromosomally normal. Their occurrence is thought to be multifactorial, involving a combination of genetic predispositions and environmental factors.
Detection and Diagnosis
Cystic hygromas are often detected during prenatal screenings, usually through routine ultrasound examinations. An ultrasound can identify the fluid-filled mass, assessing its size and location. If a cystic hygroma is observed, further prenatal diagnostic tests may be recommended to check for associated chromosomal abnormalities.
These additional tests can include amniocentesis or chorionic villus sampling (CVS) for genetic analysis of the fetus’s chromosomes. Magnetic resonance imaging (MRI) may also be used prenatally to gain a more detailed view of the hygroma’s extent and its relationship to surrounding structures.
For infants, a cystic hygroma is usually identified during a physical examination at birth or shortly thereafter. Postnatal diagnostic imaging, such as ultrasound, is commonly used to confirm the diagnosis and assess its size and boundaries. In some instances, a computed tomography (CT) scan or MRI may be used to further assess the hygroma’s extent, especially if it is large or suspected to involve deeper tissues.
Management and Outlook
The management of a cystic hygroma is individualized, depending on its size, location, and presence of symptoms or associated conditions. For smaller, asymptomatic lesions, watchful waiting may be recommended, as some can spontaneously regress. However, this resolution is not common for larger lesions.
Surgical removal is often considered the primary treatment option for cystic hygromas, especially for those that are large, cause symptoms, or present cosmetic concerns. The goal of surgery is to remove as much of the abnormal tissue as possible while preserving surrounding structures. The complexity of the surgery can vary based on the hygroma’s size and its proximity to vital organs or nerves.
Other interventions, such as sclerotherapy, involve injecting a solution into the cyst to cause it to shrink and scar. This method is used for macrocystic lesions and can be an alternative or adjunct to surgery, especially when complete surgical excision is challenging or risky. With appropriate management, the outlook for individuals with cystic hygromas is generally favorable, though recurrence is possible.