Coagulation abnormalities associated with extensive venous malformations of the limbs: differentiation from Kasabach-Merritt syndrome

Confusion in the nomenclature of vascular malformations has been a major obstacle to the understanding of these conditions, so that misdiagnosis and treatment inconsistencies are common. Coagulation abnormalities occurring in combination with venous malformations (VM) have been misdiagnosed as Kasabach-Merritt syndrome (KMS), despite marked differences in clinical features, pathology and treatment. A homogenous group of 24 patients with diffuse limb VM was entered into a retrospective chart review study. The VM affected an upper limb in 12 patients, a lower limb in 10 and both in two. Localized intravascular coagulation (LIC) was characterized by a decrease in fibrinogen (0.5-1 g/l), an increase in d-dimers (2-64 mug/ml) and presence of soluble complex of fibrin (+ to +++). Platelet counts were normal or slightly decreased. Higher VM severity scores were associated with more severe LIC. A number of events such as sclerotherapy, surgery, bone fracture, prolonged immobilization and pregnancy or menstruation triggered conversion of the LIC to disseminated intravascular coagulation (DIC), with bleeding related to factor consumption and multiorgan failure related to disseminated microvascular thrombosis. Clinical symptoms associated with worsening of LIC were pain, thrombosis and bleeding at wound sites or during surgery. None of the patients had the large ecchymotic and inflammatory tumours seen in KMS. Graded permanent elastic compression with heparin therapy was the only effective treatment. In conclusion, VM-associated LIC is a distinctive lifelong coagulopathy that must be differentiated from KMS, which is characterized by platelet trapping within a vascular tumour of infancy. The treatment of the two conditions is very different.