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At a glance

It is characterized by an association of vascular tumors with thrombocytopenia, hypofibrinogenemia, anemia, and coagulopathy. Histologically, it is associated with two rare vascular tumors, either a kaposiform hemangioendothelioma or a tuft angioma, not a hemangioma. This medical condition is life-threatening as a result of an increased risk of disseminated intravascular coagulopathy.


Hemangioma-Thrombocytopenia Syndrome; Kasabach-Merritt Phenomenon.


Approximately 300 cases have been reported in the literature since 1940. Although it was believed to be slightly more frequent in females, most agree that it affects males and females equally. There is no racial predilection.

Genetic inheritance

Unknown; seems to be more frequent in Asia.


Ecchymotic tumor develops on a vascular lesion; it usually starts in the neonatal period and grows very quickly; tumoral growth is accompanied by thrombocytopenia and hypofibrinogenemia. This disseminated intravascular coagulation (DIC) picture is secondary to entrapment of platelets within the vascular tumor.


The triad of thrombocytopenia, coagulopathy, and a vascular tumor should be highly suggestive. The clinical presence of either a kaposiform hemangioendothelioma or a tufted angioma associated with a coagulopathy confirms the diagnosis. When suspected, a usual evaluation of the coagulation profile, including a complete CBC, platelets, fibrinogen, D–dimer, PT, and PTT should be obtained. The best imaging modality to assess the extent of the lesion is an MRI with contrast. A biopsy will confirm the diagnosis.

Clinical aspects

The presence of enlarging hemangioma-like lesion, mainly cutaneous (especially on the extremities) is essential to confirm the disease. The tumors can also be visceral. The confirmation of a DIC (decreased platelets and fibrinogen, presence of increased D–dimers) is considered pathognomonic of this medical condition when associated with the tumors previously described. Most of these patients are often inoperable. Therapeutic options include vincristine, interferon-α, steroids, ticlopidine with aspirin, or radiotherapy. Untreated Kasabach-Merritt Syndrome has a 10 to 37% mortality rate.

Precautions before anesthesia

Examine for airway involvement. Check complete blood count (platelet count), coagulation profile, bleeding time, and cross-match for blood even for minor surgical procedures. In case of visceral tumor involvement, proper evaluation for potential extrinsic compression and hemodynamic effects must be evaluated before anesthesia.

Anesthetic considerations

Potential difficult airway if oropharyngeal or neck involvement is present. Anticipate the need for blood products to treat anemia and/or coagulopathy. Do not transfuse platelets because they will immediately be trapped within the tumor with an ensuing increase in size. Effect of chemotherapy on the cardiac and respiratory system must be considered. The presence of intraabdominal tumors may lead to extrinsic compression and hemodynamic effects. The preparation for massive ...

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