What is Kasabach-Merritt Phenomenon? 

Kasabach-Merritt phenomenon (KMP) is a rare, potentially life-threatening condition. It occurs when certain fast-growing vascular tumors [kaposiform hemangioendothelioma (KHE) or tufted angioma (TA)] trap and destroy platelets, interfering with blood clotting and raising the risk of serious bleeding. Kasabach–Merritt phenomenon is also known as hemangioma thrombocytopenia syndrome.

Signs & Symptoms

Patients diagnosed with kaposiform hemangioendotheliomas or tufted angiomas are monitored for the development of Kasabach-Merritt phenomenon. Signs and symptoms of KMP include:

  • Rapidly growing reddish-brown lesions on the head and neck, trunk, shoulder area and legs
  • Pain
  • Bruising
  • Prolonged bleeding after injury or break in the skin (e.g., needle stick)


Although the presence of KHE or TA indicates a risk of developing Kasabach-Merritt phenomenon, an accurate diagnosis of KMP requires a blood test to measure platelet counts. A physician may also perform a physical exam to check for abdominal masses and to look for signs of bleeding, such as excessive bruising or "pinpoint" brown spots that indicate small blood vessel bleeding. Imaging tests such as CT and MRI may also be performed.


In many cases, several types of treatment are required to manage and treat Kasabach-Merritt phenomenon. These therapies aim to:

  • Address low platelet count
  • Control blood clotting
  • Eradicate the associated KHE or TA tumor

Treatments may include:

  • Surgery to remove the tumor
  • Embolization of the tumor to limit its blood supply
  • Medications
  • Radiation therapy (in rare cases)
  • Plastic or dermatologic surgery for reconstructive purposes

Why Choose Us?

The vascular anomalies program at Comer Children's offers an integrated and comprehensive approach to the diagnosis, care and management of vascular malformations. Our multidisciplinary team of pediatric experts works together to educate families and to evaluate and treat children with all types of these vascular lesions.

Resources & Support for Patients with Vascular Anomalies

Patient Resources at Comer Children’s

Kids want to feel like kids, even when they're sick. Our Child Life therapists use play, art and other approaches to take some of the scare away from the hospital experience and to help kids feel as normal as possible, in spite of their disease. Located near Comer Children's, the Ronald McDonald House provides a home away from home for families while their child is hospitalized.

Patient Resources & Support Groups

These organizations and support groups may be helpful to families and patients by providing support, education and treatment information on vascular anomalies.