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Potentially life-threatening emergency
Kasabach-Merritt syndrome in Infant/Neonate
Other Resources UpToDate PubMed
Potentially life-threatening emergency

Kasabach-Merritt syndrome in Infant/Neonate

Contributors: Craig N. Burkhart MD, Dean Morrell MD, Lowell A. Goldsmith MD, MPH, Keith Morley MD
Other Resources UpToDate PubMed


Kasabach-Merritt syndrome (KMS), also known as Kasabach-Merritt phenomenon, is characterized by an enlarging vascular lesion, profound thrombocytopenia, consumptive coagulopathy, and often a microangiopathic hemolytic anemia. KMS is associated with vascular tumors, especially kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). Whether KMS complicates true hemangiomas of infancy is controversial, although there have been cases associated with diffuse neonatal hemangiomatosis and visceral hemangiomas.

Affected infants typically present with a solitary cutaneous lesion either at birth or within the first year of life, although multiple cutaneous or visceral vascular tumors are also encountered in affected infants. KMS is thought to result from platelet trapping within the hemangioma, with subsequent consumption of clotting factors, leading to intralesional bleeding and a rapid enlargement of the vascular lesion. In the midst of the consumptive coagulopathy, easy bruising and even frank bleeding occur.

The rapidly enlarging vascular lesion can compress vital organs and may lead to high-output heart failure. KMS has been associated with a mortality of between 30%-40%, mostly secondary to hemorrhage.


D69.49 – Other primary thrombocytopenia

86635005 – Kasabach-Merritt syndrome

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Differential Diagnosis & Pitfalls

Vascular lesions associated with KMS:
  • Kaposiform Hemangioendothelioma
  • Tufted angioma
  • Hemangiopericytoma
  • Diffuse neonatal hemangiomatosis
  • Klippel-Trenaunay syndrome
  • Blue rubber bleb nevus syndrome
  • Hepatic hemangioma
Other conditions to consider:
  • Classic Infantile hemangioma
  • Port-wine stain
  • Cutaneous arteriovenous malformation
  • Neuroblastoma
  • Leukemia cutis
  • Angiosarcoma of skin
  • Infantile fibrosarcoma
  • Disseminated intravascular coagulation of other etiology

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Last Updated:01/17/2022
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Potentially life-threatening emergency
Kasabach-Merritt syndrome in Infant/Neonate
A medical illustration showing key findings of Kasabach-Merritt syndrome : Abdominal distension, Painful skin lesions, Tumor, Vascular plaque, Ecchymosis, PT prolonged, HR increased, PLT decreased, RBC decreased
Clinical image of Kasabach-Merritt syndrome - imageId=1859794. Click to open in gallery.
Copyright © 2024 VisualDx®. All rights reserved.