Lymphatic malformation
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# Overview
Lymphatic malformations (LM) are simple vascular malformations. Clinically they can exhibit a wide range of manifestations. They may occur as isolated anomalies, combined with other vascular anomalies such as lymphatic malformations and venous malformations, or may occur as manifestations of multi-system syndromes. Their diagnosis and management depends on their clinical manifestations, histopathological behavior, and coexisting anomalies.

# Lymphatic Malformations (LM)

## Common (cystic) LM
- Benign lesions consisting of dilated lymphatic channels or cysts lined by cells of endothelial origin with lymphatic differentiation. If these lesions are associated with overgrowth then some of these lesions belong to the PIK3CA-related overgrowth spectrum.
- These are classified as follows:
Macrocystic  LM
Microcystic  LM
Mixed cystic LM
- Macrocystic  LM
- Microcystic  LM
- Mixed cystic LM

### Macrocystic  LM
- Also called cystic hygroma, and cystic lymphangioma. A cystic growth consisting of large, interconnected lymphatic cysts lined by a thin endothelium. Usually found in neck, axilla and groin. Presents as a large, poorly delineated, translucent, soft cystic mass covered by normal skin.
- May be associated with chromosomal abnormalities such as Down syndrome, Turner syndrome. To learn more click here.

### Microcystic  LM
- Also known as 'lymphangioma circumscriptum', these lymphatic anomalies may be present at birth or may develop in first few years of life. Usual presentation is as a cluster of clear, translucent or hemorrhagic vesicles that may cause pressure symptoms as they grow in size.
- Usually affect deep seated structures and frequent locations are proximal extremities, trunk, axilla, and the oral cavity.
- Diagnosis is clinical and treatment options include surgery, sclerotherapy, radiotherapy, and laser therapy. Recently topical sirolimus has also been used. To learn more click here.

## Generalized lymphatic anomaly (GLA)
- Diffuse or multicentric proliferation of dilated lymphatic vessels that may involve skin, bones, and internal organs. The proliferating vessels resemble common lymphatic malformations but the disease involvement is multi-system. Lungs, bones and mediastinum are most commonly affected but skin, liver and spleen are commonly affected as well.Liver, spleen, and thoracic duct involvement typically indicates worse prognosis.
- Considered to b sporadic and non-hereditary, it may present in childhood or can be diagnosed later in life. Etiology is unknown but high levels of VEGFR-3 have been reported in patient population.
- ] due to leakage of lymphtic fluid is commonly encountered and is difficult to treat. Patient may present with respiratory symptoms such as chest pain, wheezing, shortness of breath, cough, repeated infections or symptoms due to involvement of other organs such as bone pain, pathological fractures, pelvic or abdominal pain, swelling, fever, internal bleeding, skin lesions.
- Diagnosis of GLA is very challenging and requires multidisciplinary input. It depends on history, examination, imaging studies such as MRI, contrast ultrasound, magnetic resonance lymphangiogram, chest X-ray,near-infrared fluorescence lymphatic imaging, nanotechnology-based MRI agents and biopsy. Sometimes surgery is required that can be both diagnostic and therapeutic.
- Management is usually focused on symptomatic improvement. Options include chest drainage, open thorax surgery, sclerotherapy, surgical removal (debulking), lymphatic anastomosis and medical therapies such as sirolimus and interferon.

### Kaposiform lymphangiomatosis (KLA)
- A rare subtype with worse pronosis. Malformed vessels occur with cluster and sheets of spindle lymphatic endothelial cells. Consumptive coagulopathy is also a feature.
- Intra-thoracic component is often the cause of mortality. Currently there are no treatment guidelines.

## LM in Gorham-Stout disease
- Lymphatic malformation in Gorham-Stout disease affect a single or multiple bones and adjacent soft tissues, leading to progressive osteolysis and invasion of the bone cortex. Was originally described as disappearing or vanishing bone disease. GSD progression often leads to visceral, abdominal and thoracic involvement that may cause effusion and ascites. The osteolysis is progressive in GSD as compared to non-progressive osteolysis in GLA.
- There are two distinct forms of GSD. Primary form involves multiple bones and tissues with multi-focal lesions as described above versus trauma induced GSD that typically involves one bone or closely adjacent bones and is usually self limited.
- The etiology has not been established and gender, genetic inheritance, or race seem to play no role but inflammation, trauma and puberty have been thought to pay a role. Activation of platelet derived growth factor pathway and up regulation of lymphangiogenesis stimulating pathways may play a role in pathogenesis. IL-6 has been found to be elevated in some patients.
- Symptoms depend on the bone involved and extent of involvement. Patient can experience chest pain, dyspnea, tachypnea, wheezing, shortness of breath, dull ache, back pain, paralysis, loose teeth and facial deformation. The involvement of thorax and development of chylothorax indicate poor prognosis.
- Diagnosis often requires clinical, radiological and histopathological evidence. Imaging studies including MRI and CT scan are often crucial. Management is often symptomatic and encompasses anti-osteoclastic medication and radiotherapy. If disease affects neuro-vascular structures then surgery is indicated.

## Acquired progressive lymphatic anomaly
- Also called  acquired progressive lymphangioma, this vascular anomaly usually presents as asymptomatic, slow growing, reddish brown or violaceous papule, plaque, macule or erythema. Histological studies show numerous, dilated, thin-walled vessels that are lined by flat endothelial cells and are proliferating. No nuclear atypia has been demonstrated in this locally aggressive tumor. The cells appear to dissect between the collagen fibers.
- Excision is usually the ] of choice but some other therapies such as Imiquimod 5% cream have been tried.

## Primary lymphedema
- Edema due to obstruction or disorder of lymphatic vessels and lymph nodes. Can present at any stage of life but majority of he cases present at puberty.
- Treatment is usually conservative by compression therapy that may include complex physical therapy, pneumatic pumps and compressive garments. Some cases may require volume reducing surgery. Lymphatic microsurgery is being tried in some experimental studies.

### Nonne-Milroy syndrome
- A hereditary disorder that usually presents as bilateral edema of lower limbs that may involve the whole extremity or may be limited to legs, feet or toes. This may or may not be accompanied by toenail changes such as upslanting toenails and deep creases in the toes, papillomatosis, hydrocele, hydrothorax, lung hypoplasia and prominent leg veins. A case of unilateral phenotype have also been reported. Swellings may be complicated by recurrent episodes of cellulitis.
- The disease typically follows autosomal-dominant pattern though cases of autosomal-recessive inheritance and variable expression has also been reported. The defect thought to be responsible has been located on VEGFR3 (FLT4) gene that codes for vascular endothelial growth factor receptor 3 (VEGFR3).

### Primary hereditary lymphedema
- Chronic edema that can appear in any body part due to blockage or malfunctioning of lymphatic channels that may lead to recurrent infections and impairment.
- Results from mutations in VEGFC gene that encodes the ligand for the vascular endothelial growth factor receptor 3 (VEGFR3/FLT4). This gene plays an important role in lymphangiogenesis.

### Primary hereditary lymphedema
- Edema typically first appears in legs and then progresses to involve the arms.
- Thought to be associated with muatation in GJC2 gene that encodes for connexin-47, a member of the gap junction connecxin family. Mutation in this gene has also been linked to Pelizaeus-Merzbacher-like disease type 1 and spastic paraplegia type 44.

### Lymphedema-distichiasis
- A syndrome that is characterized by edema that typically manifests in lower limb and distichiasis that is an anomaly of eyelashes. Distichiasis appears earlier in life than lymphedema and manifests as extra eyelashes that typically arise from meibomian glands. This syndrome has been associated with congenital heart disease, varicose veins, cleft palate, ptosis, strabismus, renal abnormalities, spinal extradural cysts, and neck webbing.
- Inherited in autosomal dominant pattern mutation in FOXC2 gene that encodes for transcription factors. Inheritance also shows variable expression.
- Diagnosis is clinical. Treatment for lymphedema is mainly conservative with management of complications such as . Treatment for distichiasis consists of symptomatic management such as ] or definitive management such as surgery, cryotherapy, or electrolysis.

### Hypotrichosis-lymphedema-telangiectasia
- Characterized by less than normal body hair (hypotrichosis), chronic swelling of the body (lymphedema), and dilated blood vessels (telangiectasia). These usually appear at birth or early in life and then progressively worsen over time. Hypotrichosis may present as absent eyebrows, eyelashes and alopecia or may manifest as sparse body hair. Lymphedema typically has predilection for lower limbs and telangiectasia are more commonly seen on palms although plantar telangiectasia are also seen. This syndrome has also been associated with cutis marmorata, hydrocele, palpebral edema, ascites, dermal atrophy, small cutaneous papular vascular lesions, skin degeneration, hydrops fetalis, pleural effusion, renal defects, aortic dilation and abnormal nails.
- Mutation in SOX18 gene that encodes for transcription factor SOX18 is thought to be the cause of this syndrome. This transcription factor is expressed widely in body tissues and that may explain the wide ranging manifestations of this syndrome. Inheritance can both be autosomal-dominant and autosomal-recessive.
- There is no definitive treatment for this syndrome. Management is based on genetic counseling and symptomatic treatment.

### Primary lymphedema with myelodysplasia
- Also called Emberger syndrome, this anomaly presents with wide variety of phenotypes including congenital sensorineural deafness, lymphedema, myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), hypotelorism, epicanthic folds, long tapering fingers and/or neck webbing, and generalized warts. Lymphedema has predisposition for lower limbs. Patient may present with complication of these phenotypes such as infections, bleeding and recurrent cellulitis.
- Deficiency of transcription factor GATA2 due to mutations in GATA2 gene is thought to play the critical role. Inheritance tends to follow autosomal-dominant pattern.
- Screening for GATA2 muations is indicated in patients who present with lymphedema and hematological abnormalities. Children should be screened for hematological disorders if they present with lower limb lymphedema. Besides symptomatic treatment for lymphedema and standard treatment for deafness, primary stem cell transplant is indicated for hematological malignancies. 

### Primary generalized lymphatic anomaly
- Also called Hennekam lymphangiectasia-lymphedema syndrome, this disorder is characterized by generalized lymphatic anomalies such as lymphangiectasia and lymphedema, typical dysmorphic features such as flat nasal bridge, hypertelorism, small mouth and variable intellectual disability that may present as developmental delay. Lymphangiectasias are typically found in intestines and can cause generalized body swelling due to loss of proteins but can also be found in other organs such as kidney, thyroid gland and pleura.
- Mutations in CCBE1 gene are thought to be the main culprit although mutations in FAT4 gene has also be linked by some studies. CCBE1 encodes for Collagen- and calcium-binding EGF domain-containing protein 1 (CCBE1) that plays a crucial role in activation of vascular endothelial growth factor-C (VEGFC) through its collagen domain. Inheritance tends to follow autosomal-recessive pattern.
- Diagnosis depends on history and examination, lab findings, and genetic testing for associated mutations. Analysis for CCBE1 mutation should be considered in patients presenting with unexplained lymphatic anomalies, and/or unexplained intellectual disability. No definitive management is available at this point. Conservative measures for lymphedema and protein deficiency, and rehabilitation for intellectual disability is the mainstay of management.

### Microcephaly with or without chorioretinopathy, lymphedema, or mental retardation syndrome
- As name indicates, this syndrome is characterized by microcephaly that is often accompanied by intellectual disability, congenital lymphedema and ocular findings. Ocular defects, often because of chorioretinal dysplasia, may include peripheral retinal pigmentation, retinal folds, chorioretinopathy, widespread chorioretinal atrophy, hyperopia, small corneas, nystagmus and small optic nerves. Microcephaly can be variable and imaging often shows small size brain. Intellectual disability can also vary from normal developmental to severe mental retardation. Lymphedema most often involves lower limbs and may or may not resolve spontaneously. Facial features are distinct with broad nose, anteverted nares, upslanting palpebral fissures, a rounded nasal tip, a long philtrum, a pointed chin, a thin upper lip, prominent ears, and patient may also have atrial septal defects.
- Mutations in KIF11 gene that encodes for spindle motor protein of kinesin family, a protein that plays a role in mitosis, are thought to cause this syndrome. These mutations can be sporadic or hereditary, and when hereditary they follow autosomal-dominant pattern with variable expression and reduced penetrance.
- Diagnosis requires genetic testing in addition to clinical findings. Long term cardiac and ophthalmologic follow-ups are recommended.

### Lymphedema-choanal atresia
- A very rare syndrome described in 1982 in a Middle Eastern family when individuals in the family presented with bilateral posterior choanal atresia with other developmental abnormalities such as high arched palate, hypoplastic nipples, pericardial effusion, and pectus excavatum. Follow up detected lymphedema in five individuals with choanal atresia in the family later in 1991.
- Deletion in PTPN14 gene that appeared to follow autosomal-recessive pattern are thought to be the cause. This gene encodes for a protein that is thought to be involved in cell-signaling pathways and regulation of cellular functions.