Lymphatic Anomalies

The ISSVA classification system was updated in 2014 and is based on John Mulligan's original classification from Boston Children's Hospital

Lymphatic anomalies are classified into lymphatic tumors and lymphatic malformations, with malformations further divided into macrocystic, microcystic, combined lesions, generalized lymphatic anomaly, Gorham-Stout disease, and central conducting anomalies

Using incorrect terminology like cystic hygroma and lymphangioma causes confusion among clinicians, colleagues, and patients

Macrocystic lymphatic malformations can be described to patients as like a bunch of grapes where each grape is visible and can be accessed with a needle for sclerotherapy

Microcystic lesions are like a small porous sponge with cysts too tiny to see individually, making sclerotherapy less practical

Most lymphatic malformations are present at birth and visible at birth, though some may present later with sudden expansion

There are four general treatment options for lymphatic malformations: observation with reassurance, microinterventional therapy with needle or catheter, resective surgery, and pharmacological therapy

For very large truncal lesions extending from axilla to pelvis, surgical resection may be preferred over multiple sclerotherapy sessions to avoid significant radiation exposure and potentially unsatisfactory outcomes from residual tissue

Sirolimus (rapamycin) is an mTOR inhibitor that blocks the PIK3CA pathway, which has been shown to be a somatic mutation in many lymphatic malformations

Boston Children's Hospital received FDA funding in 2008 to study sirolimus for complicated vascular anomalies based on the hypothesis that the PIK3CA pathway controls blood vessel growth

Sirolimus improved quality of life, decreased pain, and reduced infection frequency in patients with complicated lymphatic anomalies

Preoperative sirolimus therapy can soften lymphatic tissue and decrease lesion size, making surgical procedures less extensive

Operating on patients while continuing sirolimus makes tissue softer, allows easier elevation of skin flaps, and enables more extensive resection with better closure compared to operating without the medication

Sirolimus is unlikely to be useful for purely macrocystic lesions, and the tissue expansion effect from large cysts can actually make surgery easier

Spontaneous resolution of macrocystic lymphatic malformations occurs in less than a handful of cases out of several thousand patients

EXIT procedures are not really necessary for lymphatic lesions because they are soft and compressible, allowing intubation, unlike firm teratomas

Babies with congenital lymphedema of the lower extremities can have regression to the point of non-detection on physical exam, though this is uncommon

For lesions impinging on the airway that could cause emergency if infected or bleeding occurs, observation is not a good option

Early treatment in infancy is now preferred for microcystic lesions on the face, tongue, and floor of mouth, with medical therapy rather than surgery

Burroughs rule states that if diagnosis is not classic on history, physical, and imaging, tissue biopsy is necessary

Doxycycline is used for macrocystic lesions, bleomycin for microcystic lesions (with monitoring for side effects), and sodium tetradecyl sulfate for venous components

A small amount of ethanol systemically can cause sudden fatal pulmonary hypertension

Large venous anomalies with direct macroscopic outflow to systemic veins can result in pulmonary embolism from clot induced by sclerotherapy

Venous mapping by MR, ultrasound, or venography is essential before sclerotherapy, and direct venous outflow must be obliterated first using laser, coils, or glue to prevent fatal pulmonary embolism

Most sclerotherapy worldwide is likely performed by surgeons rather than interventional radiologists because many countries lack image-guided fluoroscopy suites

When bleomycin was first used for vascular anomalies, there were reported cases of pneumonitis because practitioners didn't understand there is a maximum safe dose

Patients with central conducting lymphatic anomalies can present with subcutaneous chyle, eroding bones, chylous ascites, chylothorax, and chyle dripping from urethra, scrotum, vagina, or even from under toenails