Elevated expression of c-kit in small venous malformations of blue rubber bleb nevus syndrome.

The blue rubber bleb nevus syndrome (BRBNS, syn. bean syndrome) is a rare disease characterized by multiple cutaneous and gastrointestinal venous malformations associated with severe bleeding. However, the underlying molecular mechanisms are unknown and no targeted therapeutic approach exists to date. Here we report the case of a 19-year-old male patient with severe BRBNS in whom we analyzed the expression of tyrosine kinases frequently involved in tumor development by immunohistochemistry (vascular endothelial growth factor receptor-2, stem cell growth factor receptor (c-kit), platelet-derived growth factor receptor-β, and stem cell tyrosine kinase-1). A prominent expression of c-kit was detectable in smaller blood vessels, which also showed a moderate expression of the proliferation marker MIB1. Surprisingly, other growth factor receptors stained negatively. We therefore conclude that pharmacological inhibition of the c-kit signaling pathway in cavernous hemangiomas by selective kinase inhibitors may offer options in the treatment of BRBNS patients.