Lymphatic Malformations

What are lymphatic malformations?

Lymphatic malformations (LM) are abnormally developed clusters of lymphatic vessels that may or may not communicate with normal lymphatic vessels. They are fluid-filled spaces containing lymph fluid and can consist of large spaces (macrocystic LM), multiple tiny spaces (microcystic) or a combination of both (mixed).

When a combination of LM and venous malformation (VM) are found in the same lesion, these are called venolymphatic malformations.

Macrocystic LM	Microcystic LM

What do lymphatic malformations look like?
LM can occur anywhere in the body and are present at birth, although they may not become apparent until later in life. They appear as skin-coloured soft swellings, sometimes with tiny bubbles or vesicles over the skin. There may be a bluish hue when there is bleeding into the lesion from an adjacent vein. They usually do not feel warmer than surrounding skin.

LM usually grow in proportion with the child’s growth. They may become more obvious after episodes of local trauma, or hormonal changes occurring at puberty or during pregnancy. They can become larger and warmer after vaccinations or infections (e.g. flu, bacteria) as a result of increased lymph fluid flow due to activation of the body’s immune system.

LM are not known to become cancerous.

What causes lymphatic malformations?

LM develop due to errors in the development of the lymphatic system during pregnancy. Most LM are due to spontaneous genetic changes (mutations) that occur after conception, particularly in the PIK3CA gene.

What problems can lymphatic malformations cause?
Depending on their location, LM may cause pain/numbness, swelling, restriction of movement, breathing difficulty or cosmetic concerns. LM can occasionally become infected causing fever, pain and swelling. Occasionally they can leak fluid, sometimes blood stained, especially if they are located superficially.

Rarely, LM may be part of a vascular malformation syndrome e.g. Klippel-Trenaunay syndrome (KTS) where the affected limb can become larger or longer than the normal limb and there may be abnormal large “anomalous” vessels that may clot easily.

How are lymphatic malformations diagnosed?
LM are diagnosed with a combination of clinical history, physical examination, imaging including ultrasound, magnetic resonance imaging (MRI), and rarely, tissue biopsies.

Ultrasound:

• Non-invasive, painless test in the diagnosis of LM, as well as to assess the suitability for treatment by injection sclerotherapy or surgical excision.
• Can be performed either in the clinic or at the diagnostic imaging centre. A probe is placed on the skin over the site of the suspected LM to look at its extent and flow characteristics.
• Duration: 10 to 30 minutes depending on the size and site of the VM; will require some cooperation from the patient.

MRI:

• Provides more detail than ultrasound and can objectively demonstrate the size and extent of the lesion.
• Does not involve radiation
• Duration: 45 to 60 minutes, sometimes longer, in a noisy environment. The patient needs to stay still, thus requiring general anaesthesia (GA) for infants and younger children who are unable to cooperate. GA is administered by our team of paediatric anaesthetists.

Tissue biopsies:

• Very rarely required
• If required, this involves cutting the skin and removing a small piece of tissue to look under the microscope.
• May be done under local anaesthetic if the child is cooperative. Otherwise, it can also be performed with sedation in the ward or with GA in the operating theatre.

How are lymphatic malformations treated?
Treatment for LM may be indicated for associated functional problems or to improve the appearance. Treatment options for LM include conservative management, oral medications, sclerotherapy, lasers, surgery or a combination of these. If there are no symptoms or the symptoms are mild, treatment may not be necessary. However, the patient will be reviewed regularly.

Conservative management includes pain relief with anti-inflammatory medications, compression garment (if the lesion is in a limb) and alteration of lifestyle accordingly.

LM that are infected may require oral or intravenous antibiotics for treatment. Removal of the infected fluid through the insertion of a tube may be necessary if swelling progresses rapidly.

Definitive treatment for LM is guided by various factors including the size, extent of the lesion, the number of “spaces” within the lesion, the amount of solid tissue component, and proximity to vital structures like nerves, blood vessels or airway.

Sclerotherapy is a type of treatment that involves the injection of a special chemical into the LM to incite swelling initially but ultimately shrink the lesion.

Depending on the site, size and complexity, certain lesions are also suitable for surgical removal.

Some LM that are not easily treated by sclerotherapy or surgery may be treated with an oral medication called sirolimus.

Lasers may be a useful “add-on” treatment for LM that have a superficial component.

The various treatment options will be discussed with the patient and caregiver at the Multidisciplinary Vascular Anomalies Clinic.

The information above is also available for download in pdf format.