Imaging of the concentration profiles of the diffusants during molecular adsorption on and desorption from porous media is developing to become an important, very specific tool of monitoring the structure of these media. With the present study we refer to the remarkable phenomenon that even in the case of anisotropic porous media the concentration profiles recorded under desorption may attain isotropic patterns, irrespective of the fact that desorption is limited by anisotropic diffusion. The presentation is based on both dynamic Monte Carlo simulations and analytical considerations. (c) 2006 Elsevier Inc. All rights reserved.