A lymphangioma is a rare, benign malformation of the lymphatic system, the network of vessels managing fluid balance and immune function. These lesions are developmental errors known as hamartomas—overgrowths of normal tissue in an abnormal location—rather than true cancerous tumors. Lymphangiomas are typically congenital, present at birth, and often diagnosed in infancy or early childhood. They are fluid-filled cysts or clusters of cysts that can occur anywhere, but most frequently appear in the head and neck region.
Understanding the Developmental Origin
The formation of a lymphangioma results from the lymphatic system failing to properly develop during the first few months of fetal life. The lymphatic system starts as sacs that must connect to the venous system to drain lymph fluid back into the bloodstream. In a lymphangioma, a section of developing lymphatic tissue becomes sequestered or disconnected from these main drainage pathways.
Since the trapped vessels cannot drain the lymph fluid, they dilate and accumulate fluid, forming cystic structures. This pathology is essentially a localized plumbing defect. The exact reason for this congenital disconnection is unknown, but it results in a localized, non-malignant mass of malformed lymphatic vessels. While most lymphangiomas are evident at or shortly after birth, some may become noticeable later in childhood, often following a minor trauma or infection that causes the sequestered fluid to swell.
Classification Based on Cyst Size
Lymphangiomas are classified based on the size of the abnormal lymphatic cysts: macrocystic, microcystic, and mixed. This distinction guides treatment decisions.
Macrocystic Lymphangiomas
Macrocystic lymphangiomas, historically known as cystic hygromas, contain large cysts, typically greater than one to two centimeters in diameter. These masses are generally well-defined and often appear as large, soft, compressible swellings. They frequently occur in the neck and armpit areas.
Microcystic Lymphangiomas
These are composed of a cluster of tiny, closely packed cysts measuring less than one to two centimeters. Microcystic lesions tend to infiltrate surrounding healthy tissue, making their borders ill-defined and surgical removal more complex. They may appear on the skin’s surface as small, blister-like bumps called vesicles, which can be clear or dark if they contain blood.
Mixed Lymphangiomas
The mixed variant is the most common form, presenting a combination of both large macrocystic and small microcystic components within the same lesion. The ratio of large to small cysts determines the overall complexity of the mass and influences the choice of treatment options.
Clinical Presentation and Diagnostic Methods
A lymphangioma typically presents as a soft, spongy, non-tender mass beneath the skin. The overlying skin may appear normal or slightly bluish due to trapped blood. The most frequent locations are the head and neck, accounting for over 75% of cases, followed by the axilla, trunk, and extremities.
Symptoms arise from the mass effect, where the growing lesion compresses nearby structures. For instance, a large lymphangioma in the neck can cause serious complications such as airway obstruction or difficulty swallowing. Lesions involving the face may lead to aesthetic concerns or functional deficits, such as vision issues if the orbit is involved.
Diagnosis begins with a physical examination noting the mass’s compressible nature. While prenatal ultrasound can sometimes detect larger lesions, postnatal confirmation relies on medical imaging. Ultrasound is the initial tool to visualize the cystic nature of the mass. Magnetic Resonance Imaging (MRI) is the preferred method for detailed evaluation, as it precisely maps the lesion’s extent and its relationship to adjacent structures like nerves and blood vessels.
Management and Treatment Options
Management depends on the lesion’s size, location, and classification. A “watch and wait” approach is suitable for small, asymptomatic lesions that pose no functional or cosmetic concern, but most cases require active intervention to prevent growth or manage symptoms.
Surgical Resection
Surgery involves the physical removal of the abnormal tissue. This method is most effective for small, localized macrocystic lesions with clear margins. However, surgery carries risks of nerve damage and high recurrence rates if removal is incomplete. For microcystic lesions that extensively infiltrate surrounding tissue, complete surgical removal is often impossible without damaging normal structures.
Sclerotherapy
Sclerotherapy is a standard, less invasive alternative, especially for macrocystic and mixed lesions. This technique involves injecting a chemical agent (sclerosant) directly into the cysts to induce a localized inflammatory response. The sclerosant causes the cyst walls to adhere and fibrose, leading to the lesion shrinking.
Commonly used sclerosants include OK-432 and Doxycycline. Sclerotherapy is typically performed under image guidance to ensure accurate injection into the cystic spaces and may require multiple sessions.
Systemic Medication
For complex, widespread, or refractory lymphangiomas that do not respond well to local treatments, systemic medication is an option. Sirolimus, an inhibitor of the mammalian target of rapamycin (mTOR), works by blocking a signaling pathway that regulates cell growth and lymphangiogenesis. This oral medication has shown effectiveness in reducing the volume and improving symptoms by inhibiting the formation of new lymphatic vessels. Due to the potential for complex involvement, treatment frequently requires a multidisciplinary team approach involving surgeons, interventional radiologists, and oncologists.