Kasabach-Merritt syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 19, 2016
StartDiseasesKasabach-Merritt syndrome

Kasabach-Merritt syndrome (KMS) is an extremely rare condition that occurs in infants with no known cause. The main symptom is the appearance of a very large red lesion on the body that can cause a variety of dangerous symptoms and complications including heart failure. The syndrome is treatable with medication, radiation therapy, or surgery, but in some cases it leads to amputation or death. 


Definition & Facts

Kasabach-Merritt syndrome is a condition where a large lesion appears on the body and causes a host of issues with the blood, heart, and organs. It was first documented in 1940 when a child had a lesion appear on their leg. KMS is very rare and it is quite lethal.

It is estimated that 40% of people who have it do not survive it. It frequently appears in infants and grows very rapidly on them. In most cases, KMS appears in children less than one year old. There are instances where it appears in older children, but these are exceedingly rare. 

Symptoms & Complaints

The main sign of Kasabach-Merritt syndrome is the appearance of a huge red spot on the skin surrounded by a vast area of bruising. There might be more than one of these lesions and they are often located on the extremities.

The interior spot is large, raised, bright red and looks a lot like a big cherry angioma. The bruised area beyond it looks like a normal bruise from a single impact. This might be accompanied by petechiae, which are small reddish spots that normally are caused by bleeding in the skin. In addition to that, the patient might also have a bloated abdomen that is hard and swollen.

The patient could also have jaundice, other painful lesions and anemia. Patients who have Kasabach-Merritt syndrome often also bleeding, which is visible blood in the urine or bloody stool. The blood will be bright red and might come in copious amounts.

The patient might have a heartbeat that is faster than normal (tachycardia), and they will have difficulty eating and difficulty swallowing (dysphagia). It is possible that the patient will go into shock due to circulatory overload and high-output heart failure. In some cases, the lesion is internal. The patient will have all of the other symptoms, including a bloated abdomen and red spots on the face.


The actual cause of Kasabach-Merritt syndrome is not known. It could be caused by abnormal spindle cells that are genetically inherited. In almost every case, it is linked to a tumor. Some children are born with a vascular tumor known as a hemangioendothelioma. These tumors are fairly common and are almost always benign. In rare cases, they cause Kasabach-Merritt syndrome. These tumors can appear in the arms, legs, face, pelvis, and torso.

If the tumor is large or grows at a swift rate, it can trap blood platelets and cause the body to have a lower amount of platelets than it needs to function properly. That condition is called thrombocytopenia.

In addition, the tumor uses up fibrinogen which means that bleeding can worsen. Blood clots can form throughout the body, which can cause internal bleeding that can be quite severe. In essence, this syndrome causes a chain reaction of effects that create a wide variety of dangerous health conditions.

Diagnosis & Tests

The physician will do a blood test. They will be looking to see if the patient has a low amount of platelets. If this is the case, the doctor will then want to check for vascular lesions, which usually appear on face as red splotches, white spots, or reddish rashes.

The blood test will also give the doctor other clues, including prothrombin time, which will indicate how severe the syndrome is at that particular point in time. In addition to the blood test, the doctor will do a blood culture to make sure the patient doesn't have sepsis.

They will do a chromosome test to see if this is the result of a genetic disorder. Usually there will be a diagnostic test or scan of some kind, including a magnetic resonance imaging (MRI) scan, a radiographic scan or a doppler flow study. If the patient does have Kasabach-Merritt syndrome, the doctor will do a radionuclide scan, in which a chemical is given to the patient which will allows the doctor to see bones and organs in the scan. This scan is done to get a look at parts of the body that can't be seen with an X-ray.

Treatment & Therapy

There is no one best way to treat Kasabach-Merritt syndrome. In fact, many treatments are not even FDA-approved, but have found success. If a lesion is not too big, the physician might opt for surgery. In some case, if the lesion is on a limb, it might need to be amputated.

If surgery is not an option, than the doctor might use radiologic procedures or intermittent pneumatic compression, which is where air is pumped into a sleeve attached to a limb that can help improve circulation.

In most cases, the physician will prescribe corticosteroids and aminocaproic acids to treat bleeding. Sometimes the patient will receive injections of interferon alfa, a medication often used to treat cancer and hepatitis.

Doctors use many other drugs, including dipyridamole, ticlopidine, cryoprecipitate, heparin, vincristine, and actinomycin D. If a child is treated and reaches the age of two, they are very likely to survive. KMS is not a recurring syndrome.

Prevention & Prophylaxis

Kasabach-Merritt is difficult to prevent because people are born with it. There has been no proven link that it has anything to do with anything that happens during pregnancy. In the vast majority of cases, the tumor does not lead to Kasabach-Merritt syndrome.

This condition is very rare and can be treated successfully if it is diagnosed swiftly. The most important preventative measure is to monitor a child, and if any spots or lesions appear on their body, a physician must immediately be contacted.