Lymphatic Malformation
A lymphatic malformation is a congenital abnormality of the lymphatic system, in which clusters of abnormally formed lymphatic channels develop in the skin, soft tissues, head and neck, chest, abdomen, or extremities. Lymphatic malformations can be macrocystic (with one or more large fluid-filled cysts), microcystic (with many small channels), or mixed. They are present from birth but may not become noticeable until later in life, and they range from small, stable lesions to extensive ones that affect function or organ systems. MRI is the central imaging tool, and care is typically delivered by multidisciplinary vascular anomaly teams.
What is it?
The lymphatic system is a network of thin-walled vessels and tissues that carries lymph fluid throughout the body. It plays important roles in immune function, in returning fluid and proteins from the tissues back to the bloodstream, and in absorbing fats from the digestive tract. During early fetal development, lymphatic channels form in close coordination with blood vessels. When this process does not occur normally, lymphatic malformations can develop—localized clusters of abnormally formed and dilated lymphatic channels that are present from birth and grow proportionally with the patient.
Lymphatic malformations are classified by the size of the abnormal channels and by their pattern. Macrocystic lymphatic malformations consist of one or more large, fluid-filled cysts (often greater than approximately 1–2 centimeters), historically sometimes called “cystic hygromas,” particularly in the head and neck. Microcystic lymphatic malformations consist of many small lymphatic channels and often appear as ill-defined, infiltrative thickening of skin and soft tissue. Mixed lymphatic malformations combine features of both. Some lymphatic malformations involve specific anatomic areas (such as the orbit, tongue, airway, mediastinum, or abdomen), and complex or “generalized” lymphatic anomalies—such as generalized lymphatic anomaly (GLA), Gorham-Stout disease, kaposiform lymphangiomatosis, and central conducting lymphatic anomalies—are rare but important diagnoses with specific features and management.
Most lymphatic malformations are sporadic and arise because of changes in specific genes (often in the PI3K/AKT/mTOR signaling pathway, particularly PIK3CA) within the cells of the abnormal lymphatic channels themselves. Some are associated with broader syndromes, including conditions in the overgrowth spectrum (such as CLOVES syndrome and Klippel-Trénaunay syndrome), and certain chromosomal conditions can be associated with lymphatic anomalies identified prenatally.
The appearance and symptoms depend on size, depth, location, and the type of lymphatic malformation. Lesions in the skin and soft tissues often appear as soft, painless swellings that may transilluminate (light shines through them in macrocystic forms). Microcystic lesions can produce skin discoloration, small fluid-filled blisters, or thickened, infiltrative tissue. Lymphatic malformations can enlarge rapidly during or after viral infections or minor trauma, often because of bleeding into the cysts or infection within the malformation. Lesions in particular locations can have specific consequences: head and neck lymphatic malformations can affect the airway, swallowing, speech, or eye; chest lesions can affect the lungs and heart; abdominal lesions can affect the bowel or other organs; and lesions involving bone can cause structural changes. Recurrent infection within a lymphatic malformation is a common challenge.
Diagnosis often begins prenatally for large or characteristic lesions, especially in the neck. After birth, ultrasound is frequently the initial imaging study and can show characteristic fluid-filled cystic structures. MRI is the most useful single imaging test for detailed characterization, mapping the extent of the malformation, evaluating involvement of nearby structures (such as airway, vessels, nerves, muscle, and bone), and planning treatment. CT can be useful in some situations, particularly when bone or airway involvement requires detailed assessment. Endoscopy may be helpful for airway, gastrointestinal, or other site-specific evaluation. Genetic testing is considered in selected complex, familial, or syndromic cases. In rare generalized or complex lymphatic anomalies, specialized lymphangiography can characterize the central lymphatic system.
Important to Know
Management of lymphatic malformations is highly individualized and depends on the type, size, location, symptoms, and impact on function. Care is typically delivered by multidisciplinary vascular anomaly teams that may include interventional radiology, vascular medicine, plastic and reconstructive surgery, dermatology, hematology, head and neck surgery, pediatric surgery and pediatric specialists, ophthalmology, pulmonology, gastroenterology, infectious disease, and genetic counseling, among others.
Small, asymptomatic lymphatic malformations often require no specific treatment beyond reassurance and periodic monitoring. Supportive measures—such as good skin care, prompt treatment of infections, and individualized activity guidance—are important. Patients with extremity lymphatic involvement may benefit from compression therapy and lymphedema management.
For symptomatic or progressing lymphatic malformations, image-guided sclerotherapy is one of the most common treatments, particularly for macrocystic lesions. Specialized sclerosing agents—such as doxycycline, bleomycin, ethanol, OK-432, and others—are injected directly into the abnormal lymphatic spaces under imaging guidance, causing the channels to scar and shrink. Multiple sessions may be required. Surgery is reserved for selected cases—alone or in combination with sclerotherapy—and can be particularly useful for well-defined lesions, lesions causing significant functional concerns, or residual disease after other treatments. Laser therapy can be helpful for skin involvement and small superficial blisters.
Targeted medical therapies have become increasingly important for extensive, complex, or refractory lymphatic malformations. Sirolimus has been shown to reduce the size and symptoms of many complex lymphatic anomalies. Newer agents—including specific PI3K inhibitors (such as alpelisib) and AKT inhibitors—target the underlying signaling abnormalities and are being used in selected patients under specialized care.
Infection within a lymphatic malformation is common and is treated with appropriate antibiotics. Patients with significant or syndromic disease may benefit from a clear plan for recognizing and managing infections quickly. Management of complications—such as airway involvement, severe bleeding, leakage of lymph fluid, or organ dysfunction—is an important part of care.
Lymphatic malformations generally persist throughout life. Even when treatment is successful, periodic follow-up is often needed to monitor for changes and address recurrent or new symptoms. Patients with complex or syndromic conditions—and their first-degree relatives, when appropriate—may benefit from genetic counseling and screening.
Red flag symptoms include sudden severe swelling, pain, or change in a known lymphatic malformation; signs of infection (such as redness, warmth, fever); sudden difficulty breathing or swallowing (particularly with lesions of the airway, head, or neck); severe bleeding; significant fluid leakage; sudden vision changes (with orbital lesions); or any sudden neurological change. These warrant prompt or urgent medical evaluation.