Lymphatic Malformation (Cystic Hygroma)

 
Various lymphatic malformation lesions. 1st and 2nd lesions are commonly called "Cystic Hygroma" which is currently called macrocystic lymphatic malformation. Macrocystic lesions (cystic hygroma) typically easily compressible. 3rd lesion is a small lymphatic malformation (cystic hygroma) in the elbow. 3rd lesion involving the 2nd and 3rd toes. 2nd and 3rd lesions are not easily compressible due to microcystic component of the malformations (see the text). 

 

    Lymphatic malformations (cystic hygroma or lymphangioma) are usually apparent in young children. These lymphatic birthmarks appear in various forms, including as localized small lesions, or in the diffuse involvement of an extremity or particular body part or organ system. lymphatic malformations (cystic hygroma or lymphangioma) are usually classified as microcystic, macrocystic, or mixed. The medical term cystic hygroma, which was commonly used for macrocystic lymphatic malformatins located in the neck, is no longer used in modern medical terminology. Most lymphatic malformations (approximately 75%) occur in the cervicofacial region. The overlying skin can be healthy, or it may have tiny characteristic vesicles.
Cervicofacial lymphatic malformations (lymphatic birthmarks) may be associated with the overgrowth of the mandibular body. Lymphatic malformations of the floor of the mouth and tongue are usually characterized by vesicles, swelling, and bleeding. In most cases, the airway is involved to some degree. Lymphatic malformations of the orbit typically cause proptosis (sudden proptosis is usually due to intralesional bleeding), which may require surgical or interventional decompression to save the optic nerve. Mediastinal lymphatic malformations often accompany cervical lymphatic malformations (cystic hygromas) and/or axillary lymphatic malformations (lymphatic birthmarks). 

Lymphatic malformations in an extremity can cause diffuse or localized swelling with soft-tissue and skeletal overgrowth. When located in the pelvis, lymphatic malformations or lymphatic birthmarks are usually associated with bladder outlet obstruction, constipation, or recurrent infection. Disappearing bone disease (Gorham-Stout syndrome) is a rare disease entity that is considered an lymphatic malformation (birthmark) with progressive osteolysis. Please click here to see a detailed article on lymphangiomatosis (PDF format). 

Diagnosis: Most cases are clinically obvious and require no imaging studies for diagnosis. However, MRI is particularly useful to fully evaluate this abnormality. Interestingly, cysts in microcystic lymphatic malformation or a lymphatic birthmark are usually too small to identify on images; therefore, microcystic lymphatic malformations may easily be confused with other solitary masses or soft-tissue abnormalities. The MRI findings of lymphatic malformation (cystic hygroma or lymphatic birthmark) are characteristic. The cysts have low signal intensity on T1-weighted MRI and marked hyperintensity on T2-weighted MRI. Fluid-fluid levels within the cysts are common. Similar to venous malformations (cavernous hemangioma), high-flow vascular signal voids and flow-related enhancement are not expected in lymphatic malformations. After the intravenous administration of contrast material, the lesion or lymphaticbirthmark may show mild enhancement of the septae and walls, which creates a characteristic enhancement pattern (rings and arcs). Most LMs, however, are not enhancing; this is the most apparent difference between lymphatic malformation (lymphatic birthmark) and venous malformation (cavernous hemangioma) on MRI. Click here to go to a related article (Appropriate Diagnostic Workup for Birthmarks). 

 

                  
MR images of LM lesions. 1st lesion is in the tongue and tongue base. 2nd lesion is simply a large cystic lesion with a fluid-fluid level, which is due to bleeding into the lymphatic cystic lesion.  The 3rd image is a radiograph after contrast injection into the lymphatic malformation (cystic hygroma). This is commonly performed before any sclerosant substance injection.

With microcystic lesions, the enhancement pattern may appear to be more solid compared with that of macrocystic LMs, and it may be confused with other soft-tissue abnormalities. Occasionally, enhancement of the cysts may be seen after LMs are treated (with either surgical or intralesional injection) or in mixed lymphaticovenous malformations. Large and/or anomalous venous channels are often seen. In Gorham-Stout syndrome (disappearing bone disease), bone lesions are best demonstrated with T2-weighted spin-echo images. MRL shows the dilated or interrupted lymphatic channels, especially those in the limbs. The characteristic imaging feature of macrocystic LM of the neck (cystic hygroma) is a single large cyst just posterior to the parotid gland, with or without septae. These macrocystic LMs usually demonstrate fluid-fluid levels. Pharyngeal cleft cysts should be carefully excluded. LMs of the floor of the mouth and tongue are usually microcystic and diffuse, and they usually have minimal or no contrast enhancement. In the extremities, LMs may be similar to VMs, particularly on T2-weighted images, although no contrast enhancement is expected in LMs. Contrast enhancement is typical of VMs. Angiographically, LMs are usually avascular lesions, although a prominent capillary blush can be seen in lesions associated with bleeding. Anomalous and prominent veins, however, are frequently present. Although conventional contrast lymphangiography is rarely performed today, it is useful in determining the precise location of lymphatic leaks.

First 2 images demonstrating bone changes that may be seen with lymphatic malformation involvement.1st image is an axial CT image showing multiple bone defects in the right hip bones. 2nd image is a T2 weighted MR image showing deformed pelvic bones with diffuse lymphatic involvement. 3rd image is a subtraction radiograph obtained during an iodinated contrast material injection into a lymphatic malformation that is located in the orbit. 

Treatment: Most macrocystic cystic hygroma or lymphatic malformations can be easily treated with sclerotherapy.  Some cystic hygroma lesions or microcystic or mixed lymphatic malformation lesions can be treated surgery.                                     

 
 

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