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.