What is Kasabach-Merritt syndrome?

From the Guidelines

Kasabach-Merritt syndrome is a rare, potentially life-threatening condition characterized by the combination of a rapidly growing vascular tumor and severe thrombocytopenia with consumptive coagulopathy, typically associated with kaposiform hemangioendothelioma or tufted angioma, rather than infantile hemangioma 1.

Key Characteristics

• The syndrome primarily affects infants and young children, usually presenting within the first few months of life.
• It occurs when platelets become trapped and activated within the abnormal blood vessels of the tumor, leading to consumption of clotting factors and severe bleeding complications.
• Patients typically present with a rapidly enlarging, purplish mass that may be painful, along with bruising, petechiae, and potentially dangerous internal bleeding.

Diagnosis and Treatment

• Diagnosis requires a multidisciplinary approach involving hematologists, oncologists, and interventional radiologists.
• First-line therapies often include corticosteroids and vincristine, with other treatment options including propranolol, sirolimus, interferon, embolization procedures, and occasionally surgical removal of the tumor when feasible 1.
• Prompt diagnosis and treatment are crucial as the condition carries significant mortality risk, primarily from hemorrhage, though outcomes have improved with modern treatment approaches.

Important Considerations

• Kasabach-Merritt phenomenon is not associated with infantile hemangioma, but rather with other vascular neoplasms, such as kaposiform hemangioendothelioma and tufted angioma 1.
• The incidence of infantile hemangioma is increased among preterm infants, but this is a distinct condition from Kasabach-Merritt syndrome 1.

From the Research

Definition and Characteristics

• Kasabach-Merritt syndrome is a rare condition characterized by the presence of a vascular tumor, thrombocytopenia, and a hemorrhagic diathesis 2.
• It is also known as Kasabach-Merritt phenomenon (KMP), a consumptive coagulopathy associated with specific vascular tumors, such as kaposiform hemangioendothelioma and tufted angioma 3, 4, 5.
• The syndrome is marked by profound thrombocytopenia, hypofibrinogenemia, elevated fibrin split products, and rapid tumor growth, which can be life-threatening 5.

Clinical Presentation

• The clinical presentation of Kasabach-Merritt syndrome includes a triad of vascular tumors, thrombocytopenia, and a hemorrhagic diathesis 2.
• Patients may also exhibit severe symptomatic anemia, and the tumor can be aggressive, inflammatory, and purpuric 4, 6.
• The syndrome typically manifests in infancy, with high morbidity and mortality rates 6.

Management and Treatment

• There is no standard protocol for the management of Kasabach-Merritt syndrome, and treatment remains challenging without consensus on the optimal medical management 3.
• Various treatment options have been reported, including systemic corticosteroids, vincristine, propranolol, and rapamycin 3, 4, 6, 5.
• Early diagnosis and initiation of treatment in a closely monitored setting are essential to ensure good outcomes 6.
• The use of combination therapy, such as vincristine and propranolol, has been reported to be effective in some cases 6.