The Role of Pediatric Interventional Radiology in Lymphatic Malformation Therapy

The treatment of lymphatic malformations is complex and requires a multidisciplinary team. Pediatric interventional radiology expertise in treating vascular malformations in general is not readily available in all children’s hospitals.

A multidisciplinary team, including pediatric interventional radiologists, has been well established at CHOP since 1991. Currently, there are two pediatric interventional radiologists with a special interest in treating vascular malformations, including lymphatic malformations. These radiologists attend bimonthly vascular malformation clinic held in collaboration with the Division of Plastic and Reconstructive Surgery.

Since the creation of the Center for Fetal Diagnosis and Treatment at CHOP in 1995, pediatric interventional radiology has provided prenatal consultations with the family once a fetus is diagnosed with a lymphatic malformation.  The advantage of this service is tremendous, as therapeutic expectations and outcomes can be clearly aligned and the treatment plan can be initiated in a timely fashion post-delivery.

Pediatric interventional radiology offers a minimally invasive approach to the treatment of these lesions and in many situations treats these lesions in combination with specialty surgical services (pediatric general surgery, plastic surgery and otolaryngology), especially when the location is challenging. The majority of lymphatic malformations occur in the head and neck region. The prompt initiation of sclerotherapy can obviate the need for tracheostomy in neonates with extensive lesions, when multiple close interval sessions of sclerotherapy are performed.

Lymphatic malformations are highly variable in presentation and therapeutic options need to be tailored to the morphology and location of the lesion. There are three classifications of lesions on imaging:

• Macrocystic (larger cysts >1-2 cm)
• Microcystic (smaller cysts <1 cm often sub mm)
• Mixed lesions comprising both elements

Sclerotherapy more recently tends to be the procedure of choice since these lesions tend to be diffuse and infiltrate/compress vital neurovascular structures, making complete surgical resection a challenge. When approaching sclerotherapy of these lesions, the morphology is key. This can change over time so postnatal imaging is ideal to determine the therapeutic approach. Microcystic lesions are directly injected, and macrocystic lesions are preferentially treated with multiday catheter-based therapy.

In our program, doxycycline is the sclerosing agent of choice as it tends to be less neurotoxic than agents such as ethanol. When lesions are confined to critical areas such as the orbit, airway, tongue and floor of the mouth, more recently small doses of the chemotherapeutic agent bleomycin is the agent of choice as it causes less post-procedure swelling.

A collaborative multi-specialty approach is key when treating lymphatic malformations, especially in challenging areas. Pediatric interventional radiology works closely with otolaryngology and treats airway lesions under direct visualization with laryngoscopy in the operating room. Retro-orbital lesions are treated in the presence of an ophthalmology attending, with careful pre- and post-procedure globe pressure measurements performed and close post-procedure clinical ophthalmologic observation.

Lymphatic malformations can be so microcystic that they appear “solid” on imaging and diffusely infiltrative. These lesions are challenging to treat with sclerotherapy or surgical resection. In collaboration with our oncology colleagues, systemic medical therapies such a rapamycin are used in conjunction with sclerotherapy if possible. The care of each child and family with a lymphatic malformation requires a tailored approach customized to the morphology and location of the lesion and the expectations of the family. CHOP provides a very comprehensive multidisciplinary vascular malformation service that is both patient and family centered and reflects the individual and combined strengths of the team.

Figures: (A) Newborn male (3 kg) with large lymphatic malformation on left neck, (B) macrocystic on T2 weighted MRI, (C) treated twice with catheter directed sclerotherapy, (D) demonstrating >90% reduction in the lesion size on MR and (E) clinical examination.