What is Kasabach-Merritt syndrome?

From the Guidelines

Kasabach-Merritt syndrome is a life-threatening condition that requires prompt diagnosis and treatment, typically involving a multidisciplinary approach with corticosteroids, vincristine, and other therapies to control the vascular tumor and manage coagulopathy, as seen in studies such as 1.

Key Characteristics

• Kasabach-Merritt syndrome is characterized by a rapidly growing vascular tumor, typically kaposiform hemangioendothelioma or tufted angioma, and severe thrombocytopenia with consumptive coagulopathy.
• The condition is not associated with infantile hemangioma, but rather with other vascular neoplasms, as noted in 1.
• The underlying mechanism involves platelet trapping within the abnormal vascular channels of the tumor, leading to activation of coagulation cascades and consumption of clotting factors.

Treatment Approach

• First-line therapy often includes corticosteroids (prednisolone 2-5 mg/kg/day) for 2-4 weeks, followed by a slow taper if effective, as seen in 1.
• For non-responders, vincristine (weekly doses of 1-2 mg/m²) is frequently added.
• Other treatment options include propranolol (starting at 0.5-1 mg/kg/day and gradually increasing to 2-3 mg/kg/day divided into three doses), sirolimus (0.8 mg/m² twice daily), or interferon-alpha in refractory cases.
• Supportive care with platelet transfusions, cryoprecipitate, and fresh frozen plasma may be necessary during acute bleeding episodes, though these should be used judiciously as they can potentially fuel the consumptive process.

Important Considerations

• Surgical intervention is generally avoided due to bleeding risks but may be considered for small, accessible lesions.
• Early diagnosis and prompt treatment are crucial as mortality rates can reach 20-30% without appropriate management, highlighting the importance of studies like 1 and 1 in guiding treatment decisions.

From the Research

Definition and Characteristics of Kasabach-Merritt Syndrome

• Kasabach-Merritt syndrome is a rare condition characterized by the presence of an enlarging vascular tumor associated with thrombocytopenia, microangiopathic haemolytic anaemia, and consumptive coagulopathy 2.
• The syndrome manifests in infancy, with high morbidity and mortality rates 2, 3.
• The vascular tumors are usually benign but the associated coagulopathy may be life-threatening 4.

Treatment Options for Kasabach-Merritt Syndrome

• There are no standard guidelines established for the treatment of Kasabach-Merritt syndrome to date 2.
• Vincristine has been shown to be a safe and sometimes effective treatment option in the management of Kasabach-Merritt syndrome 3, 5, 6.
• Combination therapy with vincristine and propranolol has been reported to be successful in treating Kasabach-Merritt syndrome 2.
• Surgery may also be considered as a treatment option, especially in cases where the vascular lesion is large and life-threatening 5.

Response to Treatment

• Patients with Kasabach-Merritt syndrome have shown an increase in platelet count and a decrease in the size of the vascular lesion after treatment with vincristine 3, 5, 6.
• The average response time to vincristine therapy has been reported to be around 4-6 weeks 3, 5.
• Some patients may experience relapse, but this can be successfully treated with a second course of vincristine 3.