Features of Kasabach-Merritt phenomenon:
(1) thrombocytopenia (usually < 60,000 per µL)
(2) hypofibrinogenemia
(3) elevated D-dimer (fibrin split products)
(4) PT and PTT may be normal
(5) clinical coagulopathy (purpura, hemorrhage, etc.)
Tumors associated with the phenomena:
(1) Kaposiform hemangioendothelioma
(2) tufted angioma
Tumors not associated with the phenomenon:
(1) infantile or juvenile hemangiomas (which often involute as the patient gets older)
Patients with other forms of vascular malformations may have evidence of a consumptive coagulopathy with low fibrinogen and elevated fibrin split products, but they do not develop the severe thrombocytopenia or severe morbidity seen in the Kasabach-Merritt phenomenon.
