Sclerotherapy is a minimally invasive, nonsurgical procedure used to treat lymphatic malformations (LMs), which are abnormal growths of the lymphatic system. These congenital malformations develop before birth and consist of disorganized clusters of fluid-filled cysts instead of normal vessels. Sclerotherapy uses image guidance to inject a medical agent directly into the malformation, aiming to shrink it and alleviate associated symptoms like pain and swelling. This technique is often preferred over traditional open surgery.
Understanding Lymphatic Malformation
The lymphatic system is a network of tissues and organs that transports lymph fluid back into the bloodstream, helping rid the body of waste. Lymphatic malformations arise from a developmental error during the embryonic stage when lymphatic vessels fail to connect properly to the circulatory system. This failure creates a localized collection of abnormally dilated vessels and cysts that trap lymph fluid.
These lesions are benign and non-cancerous, but their size and location can cause significant problems. LMs are classified into three types based on the size of the fluid-filled cysts they contain:
- Macrocystic LMs: Consist of large cysts, typically greater than two cubic centimeters (sometimes called cystic hygromas).
- Microcystic LMs: Composed of numerous small cysts, usually less than two cubic centimeters, giving the lesion a spongy appearance.
- Mixed lesions: Contain both large and small cysts.
The Mechanism of Sclerotherapy
Sclerotherapy induces a controlled, localized inflammatory reaction within the malformation to cause scarring and vessel closure. The procedure is performed by an interventional radiologist, who uses real-time imaging, such as ultrasound or fluoroscopy, to guide a fine needle precisely into the abnormal cysts. Lymphatic fluid is often drained from the cyst once the needle is positioned to maximize treatment effectiveness.
A specialized medication, known as a sclerosant, is then injected directly into the cyst or lymphatic channel. The sclerosant causes chemical irritation to the endothelial cells lining the abnormal vessels. This irritation leads to damage and an inflammatory reaction. Over time, this healing process causes the cyst walls to stick together, leading to fibrosis (scar tissue formation) and the obliteration of the abnormal space.
Sclerosant Agents
Several agents are used as sclerosants, including doxycycline, bleomycin, and pure ethanol. Doxycycline, an antibiotic, is a commonly used sclerosant known to induce a scarring response. Bleomycin, an anti-neoplastic agent, has shown high response rates, particularly for microcystic lesions, by causing endothelial damage and fibrosis. Pure ethanol is highly effective but carries a higher risk of complications, requiring a tailored approach based on the malformation’s type and location.
Preparation and Post-Procedure Care
Before the procedure, patients are often required to fast for a set period to prepare for sedation or general anesthesia, which is frequently used, especially for children, to ensure comfort and precise needle placement. Sclerotherapy is carried out in a sterile environment, typically an interventional radiology suite where advanced imaging equipment is available. An intravenous line is placed to administer fluids and medication.
Immediately after the injection, the treated area will become swollen, red, and tender due to the intended inflammatory action of the sclerosant. This localized swelling is a temporary, expected reaction that signals the treatment is working. Pain management is a significant aspect of post-procedure care, with oral pain medication like acetaminophen or ibuprofen usually sufficient to manage the discomfort.
Most patients are discharged the same day, though an overnight stay may be necessary for infants or those requiring closer observation. Compression therapy, often involving a bandage or garment, is frequently applied to the treated area to encourage the cyst walls to collapse and remain closed. Patients are advised to look for signs of infection, such as a high temperature or excessive localized heat and pain, which would require prompt medical attention.
Expected Treatment Results and Follow-Up
The effectiveness of sclerotherapy is not immediate; the reduction in the malformation’s size is a gradual process that can take up to two months to become fully apparent. The primary goals are to significantly reduce the size of the lymphatic malformation and alleviate symptoms like pain, swelling, and functional or cosmetic concerns. While complete resolution is not always achieved, a substantial reduction in size is a common and successful outcome.
Many patients require multiple sclerotherapy sessions to achieve the desired result. Treatments are typically spaced several weeks or months apart to allow the body to heal from the initial inflammatory response. The number of procedures needed often depends on the type of malformation, with macrocystic lesions generally showing a better response than microcystic or mixed types. Long-term follow-up and monitoring are necessary even after successful treatment, as the malformation may recur over time.