The Koebner phenomenon
The Koebner phenomenon is a discovery made by H. Koebner in the 19th century, when he ascertained that the skin of vitiligo patients was not histologically normal. Because of this histological discrepancy, continual friction and injury increase the release of neuropeptides, substances toxic to the melanocytes, which results in new lesions, or the expansion of vitiligo or psoriasis. So, in areas with chronic friction, such as the areas where we wear tight clothing, or on which we use certain accessories like the loofah, the phone receiver, the computer mouse etc., repetitive trauma results, which may cause new lesions.
Environmental factors
In addition, the human skin is daily exposed to a variety of environmental factors, the most significant of which being solar radiation; after a sunburn, the Koebner phenomenon may appear yet again. The effect of solar radiation may be avoided by the right use of sunscreen. We apply sunscreen 20 minutes before going out and re-apply every two hours.
Some other environmental factors that may affect vitiligo are: smoking, over-exposure to toxic-chemical substances (because of the work environment), food preservatives, environmental pollution, intense stress and over-exposure to the radiation of electronic devices such as the computer, tablet, cell phone and television, which cause harm to cellular structures because of the creation of free radicals.