From the Guidelines
Kasabach-Merritt syndrome is not associated with infantile hemangioma (IH), but rather with other vascular neoplasms such as kaposiform hemangioendothelioma and tufted angioma. This distinction is crucial for accurate diagnosis and management, as the treatment approaches may differ significantly depending on the underlying vascular anomaly. According to the study published in Pediatrics in 2015 1, lesions diagnosed as "cavernous hemangiomas" are usually, in fact, deep IHs or venous malformations, and the Kasabach-Merritt phenomenon is specifically associated with other vascular neoplasms.
Key characteristics of Kasabach-Merritt syndrome include:
- A rapidly enlarging vascular tumor
- Severe thrombocytopenia
- Consumptive coagulopathy Treatment typically involves a multidisciplinary approach targeting both the vascular tumor and the associated coagulopathy. The most recent and highest quality evidence suggests that first-line therapy often includes corticosteroids, followed by a slow taper if response is observed, and other treatment options such as vincristine, propranolol, sirolimus, interferon-alpha, and embolization procedures for accessible lesions may be considered for refractory cases. Supportive care with platelet transfusions, cryoprecipitate, and fresh frozen plasma may be necessary to manage bleeding complications, though these should be used judiciously as they may worsen the coagulopathy, as noted in the study 1.
The pathophysiology of Kasabach-Merritt syndrome involves platelet trapping and activation within the abnormal vascular structure, leading to consumption of clotting factors and subsequent coagulopathy. Early diagnosis and prompt treatment are crucial as mortality rates can reach 30% without appropriate intervention. It is essential to prioritize the most recent and highest quality evidence, such as the study published in Pediatrics in 2015 1, to guide diagnosis and management 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 hemolytic anemia, and consumptive coagulopathy 2, 3, 4.
- The syndrome typically manifests in infancy, with high morbidity and mortality rates 2, 5, 6.
- It is often associated with kaposiform hemangioendothelioma (KHE) and tufted angioma (TA), which are locally invasive, aggressive vascular tumors 4.
Treatment Options for Kasabach-Merritt Syndrome
- There are currently no standard guidelines for the treatment of Kasabach-Merritt syndrome, and management continues to be a challenge 2, 3, 4.
- Treatment options include supportive care, local therapies, and drug and surgical management, with a multimodal approach to therapy often taken 4.
- Vincristine has been shown to be a safe and sometimes effective treatment option, either as monotherapy or in combination with other drugs such as propranolol, prednisone, and thalidomide 2, 3, 5, 6.
- Other treatment regimens, such as the combination of prednisone, vincristine, and thalidomide, have also been reported to be effective in resolving symptoms and achieving tumor regression 3.
Response to Treatment and Outcomes
- The response to treatment can vary, with some patients showing significant improvement in platelet count and fibrinogen level, as well as a decrease in tumor size 2, 5, 6.
- The average response time to vincristine therapy has been reported to be around 4 weeks for an increase in platelet count and 3.4 weeks for an increase in fibrinogen level 6.
- Relapse can occur, but it can often be successfully treated with a second course of vincristine 6.
- Early diagnosis and initiation of treatment in a closely monitored setting are essential to ensure good outcomes 2.