Lymphatic Malformations

1. Essentials of Diagnosis

• Incorrectly known as cystic hygroma or lymphangioma
• Typically thought of as microcystic or macrocystic based on the size of the lymphatic spaces within the malformation
• Macrocystic lesions are soft, compressible, and transilluminate
• Microcystic disease is almost always present at birth and is associated with distortion of the cervicofacial soft tissue and eventually the maxillofacial bones

2.General Considerations
     The commonly used term lymphangioma implies cellular proliferation, which is incorrect. The tissue structure of these lesions, like all vascular malformations, demonstrates no proliferative component. In the simplest terms, lymphatic malformations and all vascular malformations are birth defects.

     Fifty to sixty percent of lymphatic malformations are recognized at birth; 90% are recognized by the second year. Eighty percent of all lymphatic malformations are located in the head and neck. There is no gender predilection. A lymphatic malformation tends to be slowly progressive, growing with the child. In some instances, it is apparent that the lymphatic malformation rapidly increases in size. In these cases, it is likely that the lesion has either hemorrhaged into itself or has become infected. There are reports of spontaneous regression, although they are far from typical. With adequate follow-up, a regression is usually followed by a recurrence. The incidence of lymphatic malformations is unknown. 

3. Pathogenesis
     Lymphatic malformations are thought to arise from sequestrations of the developing lymphatic system.

4. Clinical Findings
     An MRI scan with contrast is the typical and best means for evaluating patients with a presumed lymphatic malformation. A lymphatic malformation is hyperintense on a T2-weighted image and has only a slight increase in intensity on a T1-weighted image. A lymphatic malformation does not enhance on gadolinium contrast images. Based on the radiographic appearance of the size of the lymphatic spaces located within the lesion, lymphatic malformations are then broadly categorized as either macrocystic or microcystic. Further categorization may then be made based on the location of the lesion

A macrocystic localized lymphatic malformation

     This type of staging system does offer some important prognostic information: generally, as the stage increases, the prognosis for the cure decreases. It is also generally true that facial and oropharyngeal involvement are associated with a poor prognosis. While the lymphatic malformations classification system is helpful prognostically, the staging system does not simplify the clinical complexities of dealing with children who have lymphatic malformations. A more practical classification designates these malformations as either localized and macrocystic , or diffuse and interdigitating . The therapeutic goals and appropriate treatments for the two groups are dramatically different.

An example of a congenital interdigitating, macrocystic and diffuse lymphatic malformation

     The increased use of prenatal ultrasound has led to the diagnosis of patients with lymphatic malformations in utero, which has led to some treatment dilemmas at very early stages of life. Not all fetal ultrasound diagnoses of cystic hygroma equate with the postnatal condition of lymphatic malformation. Posterior nuchal swellings are often referred to as cystic hygromas on ultrasonography. This finding is associated with chromosomal abnormalities and increased fetal death rates. These posterior nuchal swellings are not necessarily associated with lymphatic malformation. 

     Anterior and lateral neck swellings identified on fetal ultrasound, which remain persistent on repeat ultrasound, likely represent congenital lymphatic malformations and are sometimes massive (see Figure 5–6). This distinction is well known to the experienced radiologist; however, the terminology can lead to confusion. When children with massive congenital lymphatic malformations are born, they usually undergo an “exit procedure” in which the airway is stabilized by intubation, bronchoscopy, or tracheostomy. These neonates should not undergo massive neonatal dissection unless symptoms dictate the need. These procedures are more likely to result in surgical complications and require, at the least, a dedicated surgical team to perform this procedure as completely as possible.  

5. Differential Diagnosis
     When these lesions become infected or hemorrhage into themselves, their rapid enlargement can be misdiagnosed as an infected branchial cyst or acute lymphadenitis. A plunging ranula or a branchial cyst can be confused with a lymphatic malformation. Aspiration and examination of the cyst fluid should differentiate these lesions. 

6. Complications
     Diffuse microcystic cervicofacial disease often results in mandibulomaxillary hypertrophy, which is due to the direct invasion of the bone and growth of the lymphatic malformation within the bone. After the child has matured, this hypertrophy can be managed with mandibular osteotomy and, if necessary, Le Fort osteotomies. 
     A secure airway is essential in patients with diffuse microcystic cervicofacial disease. It is often necessary to perform a tracheostomy to avoid acute respiratory problems. A lymphatic malformation often swells with the onset of a general viral infection or a remote bacterial infection. This swelling typically resolves with the resolution of the infection. Occasionally, the malformation itself will become infected, which generally requires IV antibiotics. 


7. Treatment
     Multiple treatments have been employed for the management of the lesions, which indicates that none have been completely effective. It is helpful to consider treatment of the localized and diffuse groups separately. 

I. Localized Malformations
The treatment of localized malformations relies essentially on sclerosis or surgery, except in some specialized locations. Both surgery and sclerosis are very effective for localized lesions; choosing between these two modalities depends on the surgeon’s experience and the specifics of the patient’s situation.

1. Sclerosis - Numerous agents have been used in an effort to sclerose these lesions, including boiling water, tetracycline, cyclophosphamide, sodium tetradecyl sulfate, bleomycin,doxycycline, alcohol, and OK-432. OK-432 is a medication developed in Japan with extensive worldwide use. In the United States, the medication is under FDA investigation. The medication, a streptococcus culture treated and killed with penicillin, incites an immune response (delayed hypersensitivity reaction) in the location of the lymphatic malformation. Typically, the lesion swells and subsequently resolves, although it may be necessary to inject the medication several times for some lesions.

2. Laser resurfacing - Other localized lesions may present within the tongue. The tongue may be involved with small blebs that bleed and become infected. An old term used to describe this type of lesion is “lymphangioma circumscriptum.” These lesions can be managed with CO2 laser resurfacing. 

Lymphatic malformation of the tongue

3. Tongue reduction surgery - The tongue can also become massively enlarged due to lymphatic malformation . Children with this condition cannot be managed with laser and generally require tongue reduction surgery.


4. CO2 laser surgery - Glottic involvement is best managed with a CO2 laser to open lesions and debulk airway obstruction. A tracheostomy tube should always be in place for this type of airway surgery. 

II. Diffuse Malformations 
     The management of diffuse cases is much more complex and management may be a lifelong endeavor. For this reason, initial management decisions should not increase the morbidity of the disease by causing cranial nerve injury. The first goals of managing diffuse cervicofacial disease are to allow for an adequate airway and feeding, which will often require a tracheostomy and possibly a gastrostomy. Surgical management is the mainstay of treatment for these lesions.  If complete resection is not possible it may be helpful to manage different anatomic areas as individual problems. The mylohyoid muscle is a typical boundary used to divide these massive lesions into several “zones”. It is also advisable to approach the divided components of the total malformation from the “top down,” if possible. For instance, the physician should attempt to deal with the tongue before the floor of mouth and then approach the neck; this approach will prevent superior swelling of the untreated zone. Additionally, children with diffuse cervicofacial disease will also frequently require maxillomandibular reconstruction due to overgrowth of the facial bones. 
It is also advisable in the care of children with diffuse disease to involve a child psychiatrist. It is likely that these children will have long-term morbidity and a means for dealing with the psychosocial implications is essential. 

 

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