Development of Kasabach-Merritt phenomenon following vaccination: More than a coincidence?

Kasabach-Merritt phenomenon (KMP) occurred uniquely in patients with kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). We report the clinical characteristics of two patients with KHE involving the right upper arm. The patients demonstrated rapid enlargement of the lesion with severe KMP shortly after vaccination. Sirolimus was used to treat the KHE with KMP. The patients showed a quick normalization of the platelet level. The follow-up examination revealed that the size of the mass was significantly decreased. This report raises the intriguing possibility that extrinsic factors may contribute to the development of KMP in the context of an already existing KHE.