Kasabach-Merritt phenomenon is a rare, life-threatening condition in which either of two specific vascular tumors (tufted angioma or kaposiform hemangioendothelioma) traps and destroys platelets, which are a component of blood that helps 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.
Tumors usually occur shortly after birth and are equally common in males and females. These tumors can involve any area of the body but most commonly involve the extremities and chest. They are usually associated with skin changes. In the area of the lesions, the skin appears firm, warm, and purple. Tumors also can involve internal organs and can be serious when they occur deep within the retroperitoneum (abdomen).
As the tumor grows, it causes 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.