We consider a drift-diffusion model, with an unknown function depending on the spatial variable and an additional structural variable, the amount of ingested lipid. The diffusion coefficient depends on this additional variable. The drift acts on this additional variable, with a power-law coefficient of the additional variable and a localization function in space. It models the dynamics of a population of macrophage cells. Lipids are located in a given region of space; when cells pass through this region, they internalize some lipids. This leads to a problem whose mathematical novelty is the dependence of the diffusion coefficient on the past trajectory. We discuss global existence and blow-up of the solution.