The skin punch biopsies from the mastectomy scar are fixed in formaldehyde for embedding in paraffin. The tissue samples are cut into 1-2 micron thick sections and stained with Picrosirius red (PR) colour. By using polarized light microscopy, the various subtypes of collagen fibres may be visualized and differentiated. The thicker collagen fibres (type I) are red-orange-yellow and the thinner collagen fibres (type III) are green. Furthermore, the sections will be stained for elastin. Quantitatively, by means of the above-mentioned method, changes in the volume fraction of collagen type I and III, and elastin may be measured.