Fibroblasts, mast cells and Schwann cells were isolated from neurofibromas of patients with neurofibromatosis 1, and their responses to 308-nm excimer light irradiation and/or vitamin D3 or an analog (tacalcitol
1,24-dihydroxyvitamin D3) were examined in vitro. Excimer light irradiation (300 mJ/cm2) suppressed the growth of all three cell types. Exposure to 10-7 mol/L of 1α,25(OH)2D 3 (VD3) or tacalcitol suppressed the growth of fibroblasts and mast cells, but not Schwann cells. These results suggest that the different neurofibroma cell types show different responses to VD3. A combination of excimer light irradiation and VD3 is necessary to suppress the growth of neurofibroma cells in vivo. © 2013 Japanese Dermatological Association.