Kasabach-Merritt Phenomenon

What Is Kasabach-Merritt Phenomenon?

Kasabach-Merritt Phenomenon is a rare, life-threatening condition in which a vascular tumor traps and destroys platelets. Platelets are the elements in blood that help with clotting.

As the tumor grows, more and more platelets become trapped. As this occurs, the body's ability to clot decreases. This is likely to result in spontaneous bleeding, which can be fatal.

What Causes Kasabach-Merritt Phenomenon?

It is associated with other abnormal clotting conditions in which there is excessive use of clotting factors by the body.

Kasabach-Merritt Phenomenon is more likely to occur in vascular tumors that enlarge rapidly in children less than 6 months of age. These hemangiomas often occur in internal organs, such as the liver, on the head and neck area or on the extremities.

How Will Seattle Children's Treat Kasabach-Merritt Phenomenon?

Children with this disorder are initially hospitalized and monitored until they are stable.

No single treatment approach is effective, and responses to various treatments are inconsistent. The best options include a regimen of oral steroids or chemotherapy.

Steroids are generally started, with the most appropriate dose for your child given for up to four weeks and then tapered very slowly over two to three months. Interferon is given daily by injection and maintained for three to four months.

Cytoxan, a widely used chemotherapeutic agent for cancerous growths, is also sometimes used for a period of at least four months.

When bleeding does not respond to drug therapy, embolization (a highly specialized procedure in which particles are injected into the blood vessels to stop the blood flow) or surgical removal or both may be necessary.

In many patients, the lesion goes away completely with treatment. In others, a lot of the lesion may remain even when the clotting problem has been successfully treated.