Isolated lymphatic malformations (LMs) can vary widely in size, appearance, and location. They can occur almost anywhere in the body and may look and behave differently depending on where they develop and the type of cysts involved.
macrocystic
Macrocystic lymphatic malformations are large, fluid-filled cysts that often feel like soft, compressible lumps under the skin. They are sometimes described as being like “water balloons” filled with lymphatic fluid.
These cysts are usually well defined and can change in size, sometimes swelling due to infection, inflammation, or fluid buildup. They are most commonly found in the neck and underarm but can occur anywhere in the body.
Macrocystic LMs are most often associated with somatic (non-inherited) genetic changes in the PIK3CA gene and, less commonly, the BRAF gene. In some cases, macrocystic LMs may occur in association with genetic conditions such as Down syndrome, Noonan syndrome, or Turner syndrome, although this is less common.
microcystic
Microcystic lymphatic malformations may appear as clusters of tiny cysts, small bubbles, or blood-filled vesicles on the skin, or have a sponge-like appearance beneath the surface.
Microcystic LMs commonly affect the mouth, tongue, face, or limbs and may cause swelling, small blisters, or leakage of lymphatic fluid through the skin.
They are most often associated with activating somatic mutations in the PIK3CA gene, which are not inherited.
mixed
Mixed lymphatic malformations contain both large and small cysts within the same area. This combination can lead to visible swelling along with deeper, less well-defined tissue involvement. Because they contain both large and small cystic components, mixed LMs can sometimes require multiple treatment approaches.
They can occur in nearly any part of the body, including the neck, arms, legs, trunk, or chest wall. Like other isolated LMs, they are most often associated with activating somatic mutations in the PIK3CA gene.
While isolated lymphatic malformations can vary greatly in appearance and symptoms, many people live well with appropriate care and monitoring. Treatment decisions are based on the location, size, and impact of the malformation, as well as each person's individual needs.
| Macrocystic | Microcystic | Mixed | |
|---|---|---|---|
| Previous terminology | Cystic hygroma, lymphangiomas | Lymphangioma circumscriptum, capillary lymphangioma | Cavernous lymphangioma, lymphangioma (unspecified) |
| Distinguishing features | Large fluid-filled cysts or lumps under the skin | Tiny cysts that appear as cluster of small bubbles/sponge-like structure | Both visible swelling and deeper, less-defined tissue involvement |
| genetics, pathogenic gene variants | Somatic: PIK3CA mostly, occasionally BRAF | Somatic: PIK3CA | Somatic: PIK3CA |
Reference:
Sleutjes, J. K. (2022). Lymphatic Abnormalities in Noonan Syndrome Spectrum Disorders: A Systematic Review. Mol Syndromol, 1-11.
