Tattoo pigments are localized intracellularly in the epidermis and dermis of fresh and old tattoos - in vivo study using two-photon excited FLIM.

Here we show the kinetics and location of carbon black tattoo ink pigment immediately after application for the first time in vivo in human skin. Carbon black particles are located exclusively intracellularly in the skin of fresh and old tattoos. They are found within macrophages, mast cells and fibroblasts in the dermis and within keratinocytes, dendritic cells and basal cells in the continuously renewed epidermis even in 9-year-old tattoos in skin showing no inflammation.