Acute onset of coagulopathy in a patient with Kasabach-Merritt syndrome following transurethral resection of bladder tumor

Treatment of Kasabach-Merritt syndrome: a stepwise regimen of prednisolone, dipyridamole, and interferon

BACKGROUND

Kasabach-Merritt syndrome (KMS) is a rare, aggressive, vascular tumor with thrombocytopenia and consumptive coagulopathy. A standard treatment regimen for KMS has not been established. We reviewed our experience of a stepwise approach for the treatment of 10 children with KMS.

METHODS

All patients were first treated with oral corticosteroid (initially 3 mg/kg/day then 5 mg/kg/day) and dipyridamole. Interferon-alpha-2b (IFNalpha2b) was used as second therapy for steroid-resistant cases for 12 months, then tapered to an alternate-day regimen, and then discontinued. Adjunctive therapy, including embolization of the feeding vessel or chemotherapy, was additionally used in patients who failed to respond to IFN or could not be taken off IFN.

RESULTS

Ten patients were treated on this protocol with a follow-up time of 1-6 years. Oral corticosteroid plus dipyridamole was successful in four patients, but was tapered off by 12 months without recurrence in only two cases. Of the eight steroid-resistant cases, IFNalpha2b successfully induced regression of the tumor and increased the platelet count in six patients; however, IFNalpha2b was successful as monotherapy in only three cases; two patients died of aspiration pneumonia whilst on therapy and one patient could not be taken off IFNalpha2b until weekly vincristine was given (eight doses). Two other patients did not respond to IFNalpha2b in 4 weeks; embolization and vinblastine was used in one patient to induce regression of the tumor and resolution of thrombocytopenia. Hypertension developed in all children on high-dose prednisolone.

CONCLUSIONS

KMS may be treated in a stepwise approach. High-dose steroid does not result in a high response rate and is not tolerated well. The response to IFNalpha2b is more favorable, but life-threatening adverse events may occur. Chemotherapy with vincristine or vinblastine may be useful as adjunctive therapy in KMS, but experience is still limited.

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 micro g/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.