An activation of mTOR was seen in kaposiform lymphangiomatosis and kaposiform hemangioendothelioma but not in LM, whereas the activation of the ribosomal protein S6 kinase 1 (S6K1, an indicator of activated mTOR signaling), and the eukaryotic translation initiation factor 4E‐binding protein (4EBP1) which mediate an increase in protein synthesis and cell growth in lymphangiogenesis was seen in all cases of kaposiform lymphangiomatosis and kaposiform hemangioendothelioma and 40% of LM. This evidence concerns the gene EIF4EBP1 and lymphangioma.