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HomePediatrics: General MedicineKasabach-Merritt Syndrome

Kasabach-Merritt Syndrome

Practice Essentials

The combination of giant hemangioma, thrombocytopenia, and consumption coagulopathy is termed Kasabach-Merritt syndrome (KMS). KMS is an infrequent but potentially fatal complication of rapidly growing vascular lesions in infants.
See the image below.

Back of an arm showing the typical bruising associ

Back of an arm showing the typical bruising associated with Kasabach-Merritt Syndrome.

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Signs and symptoms of Kasabach-Merritt syndrome

Signs and symptoms in KMS include the following:

Visible cutaneous giant hemangioma or multiple smaller hemangiomas, usually on the extremities

Enlarged abdomen

Hepatomegaly or jaundice

Petechiae, bruising, and frank bleeding

Painful lesions

Anemia

Physical findings may include the following:

Cutaneous hemangioma, often appearing as a large irregular bruise anywhere on the body and often circumscribed by widespread, overlying, shiny and dusky, purple skin

Kaposiform hemangioendothelioma (KHE) or tufted angioma (TA) – Blue or reddish-brown discoloration and skin induration

Petechiae and bruising

Painful, tender lesions

Bleeding from thrombocytopenia and coagulopathy (locally and, at times, distantly [disseminated intravascular coagulation (DIC)])

Tachycardia, feeding difficulty, and shock (signs of high-output cardiac failure)

Pallor (suggestive of anemia)

See Presentation for more detail.

Diagnosis of Kasabach-Merritt syndrome

Any infant with unexplained thrombocytopenia, with or without evidence of DIC, should be evaluated for visceral or hidden vascular lesions (especially of the liver or spleen).

Laboratory studies that may be helpful include the following:

Complete blood count (CBC) count with differential, reticulocyte count, platelet count, and peripheral smear examination

Prothrombin time (PT) and activated partial thromboplastin time (aPTT) – These are prolonged in patients with significant DIC

Fibrinogen, fibrin degradation product (FDP), and D-dimer levels – The first are reduced in DIC, and the second and third are elevated

Blood culture (to exclude sepsis)

Chromosome tests (to exclude certain genetic syndromes)

Diagnostic imaging is obtained as appropriate and may include the following:

Radiography

Computed tomography (CT)

Magnetic resonance imaging (MRI)

Doppler flow studies

Radionuclide scanning

Although formal staging is not usually performed, documenting the extent of the invasion of the hemangioma into normal tissue is important for possible subsequent treatment with surgery or radiation. Hemangiomas do not metastasize.

See Workup for more detail.

Management of Kasabach-Merritt syndrome

No single pharmacologic therapy has been proved most effective in patients with KMS. Agents that have been tried (most of them not specifically FDA-approved for this application), with varying success, include the following:

Corticosteroids (most commonly used)

Interferon alfa

Aminocaproic acid (to treat bleeding)

Aspirin

Dipyridamole

Ticlopidine

Pentoxifylline

Cryoprecipitate

Heparin

Vincristine (80% response reported)

Cyclophosphamide

Actinomycin D

Propranolol (unlike in infantile hemangioma, response is poor)

Nonpharmacologic treatment modalities include the following:

Surgical resection (when lesions are not too large or surgically inaccessible) – Wide local excision is recommended but may be difficult; amputation may be necessary for intractable lesions involving a limb

Interventional radiologic procedures (when surgical treatment is not feasible)

Intermittent pneumatic compression (most useful for a vascular lesion located on an extremity)

Radiation therapy (now largely abandoned because of long-term adverse effects)

See Treatment and Medication for more detail.

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