Lymphatic malformations are benign lesions of vascular origin that show lymphatic differentiation. Specifically, they are vascular malformations and not vascular tumors as per the 2018 ISSVA classification of vascular anomalies 5.
This article focuses on the general features of lymphatic malformations. For a specific discussion in other locations, please refer to:
head and neck: cystic hygroma (cystic or nuchal lymphangioma)
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Terminology
These malformations were formerly called lymphangiomas. This expression is out-of-date according to the 2018 ISSVA classification 5.
Epidemiology
They can present at any age but most often occur in the pediatric population (~90% in those less than 2 years old 3). The worldwide incidence of lymphangiomas is 1:6000-16,000 live births. Males and females are equally affected.
Associations
Clinical presentation
Generally, the presentation may be with symptoms related to local mass effect and/or hemorrhage.
For example, a lymphatic malformation within the orbit may present with progressive proptosis with acute deterioration in symptoms, the mass effect resulting in compressive optic neuropathy, diplopia/ocular muscle weakness, and orbital bruising.
The clinical examination may reveal soft, non-tender masses on palpation with a doughy consistency.
Pathology
Typically comprised of thin-walled cystic masses and can be classified according to the size of the cystic lesions 6:
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macrocystic lymphatic malformation
previously known as cystic hygroma / cystic lymphangioma, although a term still commonly used when large in the cervical region
mean diameter of cystic lesions >1 cm
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microcystic lymphatic malformation
previously known as cavernous lymphangioma
mean diameter of cystic lesions <1 cm
mixed type lymphatic malformation: both macroscopic and microscopic features
Their wall consists of connective tissue, smooth muscle, fat, blood vessels, nerve, and/or lymphatic tissue.
Location
They can occur at almost any location:
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marked predilection for the head and neck: 95% in the neck and axillary regions
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mesentery, retroperitoneum, abdominal viscera, lung, and mediastinum: ~5%
Radiographic features
Lymphatic malformations may involve more than one compartment. For instance, in the head and neck region, larger lesions tend to occupy more than one deep space, sandwiching between normal structures.
Ultrasound
multilocular cystic masses
internal septa of varying thickness
cystic contents: usually anechoic; hyperechoic if contain debris, high lipid concentration, infection or hemorrhage
wide variations exist: solid areas, or mostly solid with cystic foci
color Doppler: +/- arterial or venous flow in the septa
CT
Most lymphatic malformations appear homogeneous and cystic on CT, but some appear inhomogeneous because of the presence of proteinaceous, fluid, blood, or fat components within the lesion. It is rare for CT to demonstrate intrinsic septations. There is only minimal or no displacement/compression of adjacent structures.
MRI
Fluid-fluid levels may be seen if complicated by hemorrhage. Signal characteristics include:
T1: can be variable especially dependent on protein content
T2: usually high signal
Treatment and prognosis
Surgical excision or interventional sclerotherapy (with interferon, OK-432, or bleomycin) is often necessary 3. Other possible treatment methods include steroid therapy, laser treatment, aspiration, radiofrequency ablation, or cautery.
Differential diagnosis
Differentials will depend on which compartment or viscera is considered. Possible imaging differential considerations include:
venous malformation: demonstrate internal blood flow and central enhancement
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other cystic neck masses
teratoma: demonstrates fat or calcification
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