User:SK10DPB/sandbox

Smoker's melanosis is seen with the naked eye as a brown pigmentation of the oral tissue i.e. the gums.<1=Hedin CA: Smoker´s Melanosis. Occurrence and localization in the attached gingiva. Arch Dermatol 1977; 113:1533-1538.>[, cheeks or palate of tobacco users, mainly cigarette smokers, and is most easily seen in Caucasians, due to their lack of genetically melanin pigmentation. It is also frequently reported from many countries with genetically melanin pigmented inhabitants and besides cigarette smokers and snuff dippers also in chutta, bidi users and reverse smokers. The brown colour is melanin. In skin melanin prevents harmful UV-light to reach deeper, sensible parts of the tissue. However, if UV-light penetrates deep, some of the toxic agents developed by the UV-light-damage to the cells, are bound to melanin in the epithelial cells and travel with the ageing cells to the skin surface, where it is expelled from the tissue surface. Thus melanin serves as a toxic defence and cleaning mechanism. In the oral mucosa, where the ageing epithelial cells move faster to the surface compared to skin, a similar defence-mechanism seems to be present, but here acting to clean the mucosa from toxic chemical agents entering the mouth, for instance nicotine.

In the microscope, smoker´s melanosis is characterized by a melanin hyperpigmentation of the lower part of the oral epithelium. Melanin is produced by the dendritic melanocytes, situated close to the epithelial basal membrane. In tobacco users the melanocytes are stimulated by nicotine, probably also tar components (benzopyrenes) and other unknown toxic agents, to produce melanin granules and to distribute them out to the surrounding epithelial cells. The epithelial cells carry the toxic agents bound to the melanin granules up to the upper keratin layers, where the old cells with the embedded melanin are expelled from the mucosal surface.