Kaposiform Hemangioendothelioma

  • Overview

    Are you concerned about a  birthmark on your child? Birthmarks are common in infants, and many of them go away on their own or only need to be addressed cosmetically. However, some birthmarks are caused by tumors in the cells of your child’s blood vessels; these are more serious and need to be monitored and, in some cases, treated.

    Kaposiform hemangioendothelioma (KHE) is one of these kinds of rare tumors. Fortunately, it's benign (non-cancerous). And the dedicated, compassionate staff at Children’s Hospital Boston is incredibly well qualified to care for your child.

    Here’s what you need to know about KHE:

    • KHE is not cancer. While we refer to KHE as a tumor, it’s a benign tumor, which means it doesn't metastasize and spread to other locations in your child’s body. “Tumor” simply means abnormal growth.
    • It’s treatable. Our doctors use different medications to stop the growth of the tumor and increase your child’s platelet count. Read more in our Treatment & Care section.
    • KHE is not associated with regular infantile hemangiomas, although it’s sometimes misdiagnosed as a  hemangioma. For more information, see the Diagnosis section.
    • It’s often accompanied by a potentially serious condition called Kasabach-Merritt phenomenon, which occurs when the tumor traps and destroys platelets in your child’s blood, leading to an increased risk of bleeding.

    How Children’s approaches KHE

    Because kaposiform hemangioendothelioma is so rare, very few doctors have experience diagnosing and treating KHE. Here at Children’s Vascular Anomalies Center, we have the world’s largest database of patients with vascular anomalies, including more than 150 with KHE. When doctors anywhere in the world have questions about whether a child’s birthmark may be KHE and what to do about it, they often call us. Our physicians have evaluated more children with KHE than any other hospital in the world.

    Additionally, we approach each patient with decades of experience involving multiple disciplines, including  surgery,  plastic surgery, hematology-oncology, dermatology and interventional  radiology. We are actively reviewing our extensive database to redefine the best therapies and long-term outcomes for KHE.

    The database

    Children’s Vascular Anomalies Center has the largest database in the world of children who have experienced  Kasabach-Merritt phenomenon — currently more than 125 cases of vascular anomalies with KMP. As our database grows, it will help shine more light on this rare and often misunderstood condition.

    Reviewed by Cameron C. Trenor III, MD,
    © Children’s Hospital Boston, 2010

  • In-Depth

    If your child has been diagnosed with kaposiform hemangioendothelioma (KHE), you probably have many questions:

    • What is it?
    • Will it go away?
    • How is it treated?
    • What does it mean for my child?

    We’ve tried to provide some answers to these questions in these pages, and when you meet with our experts, we can further explain your child’s condition and treatment options.

    Is my child’s lesion painful?

    Often yes, but not in all cases. As the tumor gets bigger and more aggressive, a lesion can swell and may be very painful. This may also occur with infection, trauma to the lesion or after platelet transfusion.

    Does KHE always lead to Kasabach-Merritt phenomenon?

    Not always, although nearly 75 percent of cases referred to us here at Children’s Hospital Boston have or develop Kasabach-Merritt phenomenon.

    KHE lesions that are larger and invade into deeper tissues are more likely to trap platelets and have bleeding risk. In very rare situations, KHE can involve only your child’s bones and occasional superficial lesions; these appear to have low risk of Kasabach-Merritt phenomenon.

    How common is it?

    It’s very rare, representing less than 1 percent of birthmarks. The incidence is unknown, but is likely less than 1 in 100,000.

    Children’s Vascular Anomalies Center has the largest database in the world of information describing KHE cases — it includes more than 160 cases (as of 2010).

    What does a KHE lesion look like?

    KHE may have the following characteristics:

    • It’s usually a deep, reddish-purple.
    • It is firm and warm to the touch.
    • The skin is often shiny and tense.
    • There may be tiny purple or red spots and a bruise-like discoloration near or around the lesion.
    • About 10 percent of kids with KHE have no skin lesion and some lesions penetrate deeper than the skin into other tissues.

    Where does the lesion appear?

    It can appear anywhere on your child’s body. It is often found on the head and neck, but can also appear on the stomach, back, arms and legs — even inside the chest, abdomen or bones.


    What causes Kaposiform hemangioendothelioma?

    KHE is not inherited — researchers are still studying the cause of these rare tumors. Abnormal blood vessel formation and growth typically occurs in infancy, although it can happen prenatally and also in adults after trauma.

    Signs and symptoms

    What are the symptoms of KHE?

    Often, KHE can be misdiagnosed by your child’s primary physician, simply because the condition is so rare. Here are some signs that you can look for; if your child has one or more of these symptoms, we recommend getting a second opinion from a vascular anomalies specialist.

    • a lesion on the skin that’s getting larger than expected
    • a lesion that swells and becomes painful
    • pain with movement or decreased range of motion around the area of the lesion
    • low platelet count

    KHE may also show up with different symptoms based on the location of the lesion.

    Long-term outlook

    What is the long-term outlook for my child?

    KHE is such a rare tumor that it’s difficult to determine the long-term outlook for your child, though we are actively researching this question. Every child is unique and your care team will work with you to develop a treatment plan that works for your family. We will openly share our experience about outlook and prognosis with you.

    It’s important to get prompt medical attention when KHE is suspected to allow early discussions about treatment. This enables your doctor to attempt to shrink the tumor before it affects adjacent muscle or tissue — early treatment could also help lessen long-term complications by preventing further growth.

    The prognosis for your child depends on:

    • the extent of the disease
    • the size and location of the tumor
    • the tumor's initial response to therapy
    • new developments in treatment

    Will my child’s tumor come back after treatment?

    There is some evidence that these tumors can recur, though it is currently unclear how common this is. However, if your child’s tumor does recur, we have good success treating it again, reducing its size and stabilizing your child’s platelet count.

    What do we do after treatment is over?

    Your child should continue with regular, thorough clinic visits at least every year. The purpose of these visits is to monitor for recurrence and rare late effects from therapy.

    A typical follow-up visit may include some or all of the following:

    • a physical exam
    • blood tests
    • imaging or scans


    Q: Is kaposiform hemangioendothelioma a birthmark?

    A: No. KHE is a vascular tumor that causes a discolored lesion or birthmark on your child’s skin.

    Q: Is KHE a hemangioma?

    A: No. Hemangiomas have a different appearance, grow predictably and shrink and fade on their own. They also look different when biopsied. KHE is not associated with infantile hemangiomas, although KHE is sometimes misdiagnosed as a hemangioma.

    Q: Does my child have cancer?

    A: No. We use the term “tumor” to mean any abnormal growth. While we refer to KHE as a tumor, it’s a benign tumor, which means it doesn't metastasize and spread to other locations in your child’s body.

    Q: If it’s not cancer, why is it a problem?

    A: KHE is a problem because the tumor can affect adjacent muscle or tissue. This can result in three different kinds of problems:

    • pain/difficulty moving — If the tumor spreads into adjacent muscle tissue, your child may have difficulty moving the affected area (such as an arm or a leg). There may also be pain involved.
    • damage to an internal organ — If the tumor spreads too close to an internal organ, it can hurt that organ.
    • bleeding — As the tumor grows, it captures more platelets, putting your child at risk for bleeding. This is referred to as Kasabach-Merritt phenomenon.

    Q: Is KHE treatable?

    A: Yes, although treatment is not always necessary.

    • Our doctors use different medications to stop the growth of the tumor, improve your child’s platelet count and help prevent any complications.

    Q: What kinds of medications are used?

    A: Our doctors will often recommend steroids first and then move on to chemotherapy or interferon therapy if steroids are not effective.

    For detailed information on all aspects of treatment, see the Treatment & Care section.

    Q: What makes Children’s different?

    A: We’re home to the largest Vascular Anomalies Center in the world. We assist doctors in other states or other countries with diagnosis and treatment of vascular anomalies like KHE, evaluating about 1,000 cases of vascular anomalies annually. We have more experience evaluating, diagnosing and treating children with KHE than any other hospital in the world.

    Q: My child has a low platelet count and a birthmark that was diagnosed as a hemangioma. Should I get a second opinion?

    A: Yes. If your child’s platelet count is low and he has a vascular tumor or birthmark, you should definitely consult a vascular anomalies center.

    A low platelet count is never caused by common infantile hemangioma. Low platelets combined with a skin lesion should lead to evaluation for KHE or other benign vascular tumors like tufted angioma or cutaneovisceral angiomatosis with thrombocytopenia (CAT) — also called multifocal lymphangioendotheliomatosis with thrombocytopenia (MLT).

    Keep in mind, however, that KHE is very rare and having these two symptoms doesn’t necessarily mean that your child has a vascular tumor. There are other reasons your child may have low platelets and our experts can clarify the cause in your child.

    Q: My child has a low platelet count and our doctor recommended a transfusion. Now the lesion is bigger than ever and more painful. What happened?

    A: What happens in a platelet transfusion is that all the new platelets are quickly attracted to the tumor and trapped. Your child’s lesion will quickly grow and become extremely painful. Over time, it will shrink back to its normal size over time, but your child’s platelet count will not improve from the transfusion. We only recommend a platelet transfusion if your child is bleeding badly — not simply because a platelet count is low.

    It’s important to treat the tumor, not the platelet count. Your child’s platelet count will go up as the tumor shrinks (because it’s not trapping as many platelets). We focus on shrinking the tumor, understanding that the platelet count will normalize as your child’s tumor becomes less aggressive.

    Questions to ask your child’s doctor

    After your child is diagnosed with KHE, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you.

    Lots of parents find it helpful to jot down questions as they arise – that way, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed.

    If your child is old enough, you may want to suggest that she write down what she wants to ask her health care provider, too.

    Some of the questions you may want to ask include:

    • How will my child’s KHE be treated?
    • Will my child need to stay in the hospital?
    • What side effects or complications might my child experience due to treatment?
    • What kind of follow-up care should my child receive? How often will she need to come in?
    • How much experience does this center and my child’s doctor have with treating KHE?

    Keep family and friends up to date during your child’s treatment by creating a free Children’s CarePage.

    Dealing emotionally with your child’s birthmark

    If your child has a prominent birthmark during early infancy, you may experience a range of emotions, from disappointment to fear. Read about ways to cope with emotions you may experience, such as panic, sadness, a sense of isolation and guilt or self-blame.

  • Tests

    The first step in treating your child is forming an accurate and complete diagnosis. It’s important to understand that neither you nor (probably) your child’s regular pediatrician will be able to diagnose kaposiform hemangioendothelioma (KHE) by simply looking at the lesion.

    There’s also a related, milder tumor called tufted angioma that looks very much like KHE. Only experienced vascular anomalies specialists will be able to tell the difference between KHE and tufted angioma and other vascular anomalies.

    When should I consult a vascular anomalies specialist?

    We advise consulting a vascular anomalies specialist in three situations:

    • if your child has a vascular skin lesion and a low platelet count
    • if your child has a vascular skin lesion that seems to be growing beyond expectations
    • if your child has a vascular skin lesion that gets larger, darker and more painful after a platelet transfusion

    How is KHE diagnosed?

    When you make an appointment at Children’s Hospital Boston, we start by requesting all outside imaging, labs, notes and photographs to begin preparation for your visit. Your visit includes a complete medical history and thorough physical exam.

    We will review outside imaging studies and will not repeat studies unless necessary. After a discussion between you and your doctor, your child will have one or more of the following imaging tests, which can help determine the correct diagnosis:

    • Magnetic resonance imaging (MRI) — This high-resolution scan shows how large your child’s tumor is as well as its relationship to nearby muscles, nerves, bones and other blood vessels.
    • Ultrasound (also called ultrasonography) — An ultrasound also shows the size of the tumor and allows your doctor to see how much blood is flowing through it.
    • Computerized tomography scan (also called a CT or CAT scan) – This test is only occasionally used for KHE. A CT scan shows detailed images the area around your child’s tumor, including the bones, muscles, fat and organs. CT scans are more detailed than general x-rays, but do involve radiation exposure.
    • Biopsy — If the results of the physical exam and imaging tests are not conclusive, your doctor may take a biopsy of your child’s lesion. A biopsy is a simple surgical procedure where a doctor removes a small tissue sample.
    • Examining the tumor's cellular appearance under a microscope allows the physician to determine definitively whether your child has KHE.
    • If your child has had a biopsy done elsewhere, we can often use it instead of performing another biopsy.
    • Complete blood count (CBC) — If your child’s doctor suspects KHE, he or she will order a complete blood count to check your child’s platelet level. Other blood studies may also be helpful.

    After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best treatment options.

    Your appointment

    Questions about your visit? Read about directions, contact information and other important information. 

  • Having identified your child's condition, we're able to begin the process of treating her, so that we may ultimately return your child to good health. At Boston Children's Hospital, we consider you and your child integral parts of the care team and not simply recipients of care. You and your care team will work together to customize a plan of care for your child.

    What are the treatment options for my child?

    Kaposiform hemangioendothelioma (KHE) is a complex condition, so your child will likely be treated by some or all of the following specialists:

    • hematologist-oncologist
    • dermatologist
    • plastic surgeon
    • general surgeon
    • interventional radiologist

    Your care team (your child's doctor and an experienced vascular anomalies specialist) will outline the benefits of all the treatment options listed below with you.

    Observation — If your child has a mild lesion with no pain and a normal platelet count, your doctor may want to simply observe the tumor for a period of time.

    Steroids — Your doctor may recommend treating the tumor with steroids first. While they're not effective in most cases (around 12 percent of the tumors respond to steroids), the treatment is easier (taken by mouth) than other options and is well tolerated.

    Chemotherapy — If steroids don't work, your doctor may recommend chemotherapy to slow the tumor by interfering with the growth of blood vessel cells. While the word “chemotherapy” can be scary, rest assured that the treatment for KHE has few of the side effects of traditional chemotherapy (no hair loss and minimal or no nausea or effects on the immune system).

    The first chemotherapy drug we recommend is vincristine. Vincristine slows down the growth of the tumor and can even stop growth or shrink tumors in some cases.

    • We give children chemotherapy through an IV central line (also called a central venous catheter).
      • A surgeon will implant a small port-a-cath (you won't see it, but will be able to feel a bump) in your child's chest, which allows the medicine to go directly into a vein.
      • It's a minor surgery in which the surgeon makes a small incision and then inserts the port, linking it to a large vein in your child's chest.
      • Once the course of treatment is completed, a surgeon will remove the port-a-cath.
    • Every one to two weeks for about six months, your child will receive an IV dose of vincristine.
      • This is administered by experienced nurses and physicians either at Children's or through our partnership with the Jimmy Fund Clinic next door at the Dana-Farber Cancer Institute. This therapy can also be coordinated with a clinic or hospital convenient for you.

    Most children tolerate vincristine very well. Your care team will explain the few, minor side effects your child may experience. Being able to anticipate these side effects can help you prepare for, and, in some cases, prevent these symptoms from occurring.

    Interferon therapy — In cases where vincristine is not effective and your child is at least 12 months old, your doctor may recommend injections of interferon. Interferon is a drug that is used for a variety of disorders to limit new blood vessel formation and reduce blood supply to the tumor.

    The regimen and length of therapy is variable and is customized for your child by your doctor and care team. Injections can be given daily, three times a week or weekly and are usually continued until your child's platelet count rises and the pain around the lesion subsides.

    Other treatments

    In very aggressive cases (or situations where your child's tumor doesn't respond to any of these therapies), your doctor has other options:

    • Clinical trials — As the home of the largest vascular anomalies center in the world, we often have access to new drugs involved in clinical trials.You can search current and upcoming clinical trials here at Children's.
    • Embolization — This is a process in which a doctor inserts a block into the main artery that's feeding your child's tumor. With the blood supply cut off, the tumor will often shrink. However, KHE is most often fed by a number of arteries instead of one main artery; and if that's the case, embolization is less successful and we usually don't attempt it.
    • Surgery — Your doctor will only recommend surgery if your child's tumor is very small (and we're able to completely remove it) or extremely aggressive. Because of the location and size of these tumors, they are quite difficult to remove and the surgery can often cause more harm than good.
    • Radiation — This was historically used to try to control the growth of these tumors, but is associated with significant short- and long-term side effects. We may consider using it in conjunction with one of the other treatments in very rare cases.

    My child's doctor recommended a platelet transfusion. Is that a good idea?

    Very rarely. What happens in a platelet transfusion is that the new platelets will be quickly attracted to the tumor and trapped.

    • Your child's lesion will quickly grow and may become extremely painful.
      • Over time, the lesion will shrink back to its normal size over time, but your child's platelet count will not improve because of the transfusion.

    We only recommend platelet transfusion if your child is bleeding badly.

    • It's important to treat the tumor, not the platelet count.
      • Your child's platelet count will go up as the tumor shrinks (because it's not trapping as many platelets).
      • We focus on shrinking the tumor, understanding that the platelet count will normalize as the tumor becomes less aggressive.

    Supportive care

    We want to maximize the safety and effectiveness of whatever therapy you and your child's doctor choose. Supportive care involves preventing and treating infections and side effects of treatment to keep your child as comfortable as possible while we're working to shrink the tumor.

    Follow-up care

    Your child should have regular follow-up during and after treatment to check for recurrence of the tumor, a drop in platelet count or a worsening of the lesion. Your child's health care team will give you a schedule of follow-up care to see how your child is responding to therapy.

    We'll also want to monitor for any problems because of the tissue involved as the tumor grows. Sometimes, there can be scarring that could limit your child's movement or cause discomfort. Clinic visits after therapy are also important to monitor for any late effects of therapy.

    After we have succeeded in shrinking the tumor, there are often some residual marks on your child's skin. Depending on where they are and how large they are, you may want to consult with one of our plastic surgeons to discuss corrective options.


    Children with KHE often need multidisciplinary care. Each of these disciplines is available at Children's with experts dedicated to the care of children with complex medical conditions. Some specialists your doctor may recommend for your child include the following:

    • Physical therapists — Sometimes the tumor can affect surrounding tissue and muscles, making it hard or painful for your child to move an arm or a leg. A physical therapist can help ease the pain and increase your child's range of movement, strength and flexibility.
    • Occupational therapists — Children with KHE sometimes get behind on developing motor skills because of physical problems related to their tumors. An occupational therapist can get your child back on track.
    • Counselors — As your child gets older, he or she may be uncomfortable with the skin lesion, especially if it's in a prominent location such as on the face or neck. Our counselors can help your child deal with the psychological and social issues related to having a birthmark.

    Coping and support

    Hearing that your child has KHE may be scary. We hope that this site reassures you with reliable information and begins to prepare you for your next steps. There are also a number of other resources to help you and your family through this difficult time.

    Patient education: From the first office visit, our nurses will be on hand to walk you through your child's treatment and help answer any questions you may have — What kinds of treatment are available? What symptoms might my child have? They will also reach out to you by phone, continuing the care and support you received while at Children's.

    Parent to parent: Want to talk with someone whose child has been treated for KHE? We may be able to put you in touch with other families who can share their experience.

    Faith-based support: If you are in need of spiritual support, we will help connect you with the Children's chaplaincy. Our program includes nearly a dozen clergy representing Episcopal, Jewish, Lutheran, Muslim, Roman Catholic, Unitarian and United Church of Christ traditions who will listen to you, pray with you and help you observe your own faith practices during your hospital experience.

    Social work and mental health professionals: Our social workers and mental health clinicians have helped many other families in your situation. We can offer counseling and assistance with issues such as coping with your child's diagnosis, stresses relating to coping with illness and dealing with financial difficulties.

    On our For Patients and Families site, you can read all you need to know about:

    • getting to Children's
    • accommodations
    • navigating the hospital experience
    • resources that are available for your family

    Our Vascular Anomalies Center offers links to organizations that offer support and education for parents who have a child with a vascular anomaly.

    Integrative therapies
    Our patient-centered approach means that we want your child to not only get better, but also feel good along the way. Throughout the hospital, you¹ll find clinicians trained in therapies that can make your child feel more comfortable, learn to shift focus away from pain and enjoy some peaceful moments during what may be an anxious time. Read more about how acupuncture, guided meditation, guided imagery, massage, Reiki and therapeutic touch could help your child.
    Child Life Specialists
    "Don't forget to tell them the rules," 7-year-old Lia DiFronzo says to Amber Soulvie, her Child Life specialist. Read more about how our Child Life help children like Lia feel comfortable in the hospital.
  • Research & Innovation

    Children’s Hospital Boston is home to the world’s largest vascular anomalies center. When doctors in other states or other countries need help diagnosing or treating vascular anomalies like KHE, they come to us. We have more experience evaluating children with KHE than any other hospital in the world. And we’re constantly increasing our base of knowledge.

    KHE database

    Physicians and researchers at Children’s Vascular Anomalies Center are now reviewing our extensive database with more than 160 cases of KHE. We are actively evaluating the best therapies for KHE and studying long-term outcomes after KHE. As our database grows, it will help shine more light on this rare and often misunderstood condition. More importantly, consolidating knowledge about treatment, side effects and outcomes in this database will help us treat your child more effectively.

    Interferon therapy

    Interferon therapy is an angiogenesis inhibitor to slow the growth of new blood vessels and cut off blood supply to your child’s tumor.

    The whole idea that tumors are unable to grow beyond a certain size without a dedicated supply of blood was conceived by Judah Folkman, MD, former director of the Vascular Biology Program at Children’s.

    These days, angiogenesis inhibitors and stimulators are powerful new weapons in the battle against tumors like KHE as well as a host of other illnesses, including cancer in children and adults.

    Angiogenesis inhibitor therapy works on Folkman's principle that, rather than waging a toxic chemical and radiation battle with a tumor, doctors could starve it into submission by shutting down its blood supply.

    Today, at least 50 angiogenesis inhibitors are in clinical trials around the world, and more than 1,000 laboratories in universities and industry are conducting angiogenesis research.

    Read more about Folkman's pioneering research here.

    The VAC conducts research that may lead to the development of new, more effective therapies and perhaps ultimately result in ways to prevent these anomalies. Read more about our research

    Clinical and Translational Study Unit
     Read about a day in the life of the Clinical and Translational Study Unit at Children’s.
  •  Vascular Anomalies Center


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    Fegan Building, 3rd Floor
    Boston MA 02115


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