Kasabach-Merritt phenomenon (KMP)was first described in the 1940's.  It is a rare, life-threatening condition in which either of two specific vascular tumors (tufted angioma or kaposiform hemangioendothelioma) traps and destroys platelets.  Platelets are a component of blood that helps with clotting.  This condition is also associated with other abnormal clotting conditions in which there is excessive consumption of clotting factors.

Kasabach-Merritt phenomenon does not occur in children with infantile hemangiomas.

General Appearnce of a KHE Lesion

Kasabach Merrit Phenomenon develops in children with Tufted Angioma and KHE.  These tumors usually develop shortly after birth and are equally common in males and females. KHE and TA most commonly occure in the extremities but may occur any where in the body.  They are usually associated with skin changes, the skin appears firm, warm, and purple.

TA and KHE tumors also can involve internal organs and can be serious when they occur deep within the abdomen.

As these tumors grow, they cause more platelet trapping. This is associated with abnormal clotting and utilization of clotting proteins, creating a deficiency in these proteins. Because of this, bleeding can occur and can be fatal.

Children diagnosed with KMP will often need hospitalization where they can be monitored until they are stable.  Unfortunately there is no single treatment protocol or approach that is shown to produce consistent effective results. 

Initially, gluco-cortico steroids are given to slow the growht of the tumors.  The dosage may vary.  If the steroids are not effective then a chemotherapy agent is ussually started.  The drug Vincristine, a common cancer medication is the chemotherapy agent most often used.  If vincrisstine is not effective there are other chemotheraphy agents that can be used.  (interferon, cytoxan, amicar)  It is important to note that due to the complexity of these tumors and the serious complications that occur a multidisciplinary team of physicianse should manage these patients.

When drug therapy is not effective in the treatment of these tumors, a procedure in which particles are injected into the blood vessels of the tumor called embolization may be necessary.  Embolization stops the blood flow to the tumor.

Platelets and packed red blood cell transfusions may be given when absolutely necessary to improve blood counts.

These two types of vascular tumors may take many years to decrese in size.  It is reported that some lesions are present 10 years after diagnosis.  Improvement in blood counts often signals a decrease in the size of the tumor.

NOVA is currently working to establish a registry and support for KHE and TA families.  Please contact our office at admin@mail.novanews.org for more information.

References:

Akyuz C, Emir S, Buyukpamukcu M, et al. Successful treatment with interferon alfa in infiltrating angiolipoma: a case presenting with Kasabach-Merritt syndrome. Arch Dis Child. Jan 2003;88(1):67-8. 

Biban P. Kasabach-Merritt syndrome and interferon alpha: still a controversial issue. Arch Dis Child. Jul 2003;88(7):645-6.

Boon LM, Enjolras O, Mulliken JB. Congenital hemangioma: evidence of accelerated involution. J Pediatr. Mar 1996;128(3):329-35

NOVA PROVIDES THIS INFORMATION TO FAMILIES AS A RESOURCE. IT IS NOT INTENDED TO ENGAGE IN THE PRACTICE OF MEDICINE OR TO REPLACE THE PHYSICIAN. NOVA DOES NOT CLAIM TO HAVE MEDICAL KNOWLEDGE. NOVA DOES NOT ENDORSE ANY PARTICULAR PHYSICIAN, TREATING FACILITY OR TREATMENT PROTOCAL. IN ALL CASES NOVA AND ITS BOARD OF DIRECTORS RECOMMENDS THAT YOU SEEK THE OPINION OF A PHYSICIAN EXPERIENCED IN THE MANAGEMENT OF HEMANGIOMAS AND VASCULAR MALFORMATIONS. 

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