Normal tongue dorsum has a thin layer of white tongue moss, if there is a color form texture abnormal white, may be coccidioidomycosis, lichen planus, white spots. 1. Coccidioidomycosis. When the oral cavity is infected with staphylococcus and other bacteria, it will cause acute damage, manifesting itself as a grayish-white dense and smooth pseudomembrane on the back of the oral tongue, which can be removed around the erosion. 2. Flat moss. When there is lichen planus in the oral cavity, there can be a white thread-like composition of reticular, patchy pattern on the tongue, for a slightly light blue white patch form, irregular tongue papillae atrophy, the lesion surface is smooth. 3.White spots. The appearance of oral white spots, there may be white or gray-white homogeneous plaque above the mucosal surface, can not be wiped away, with a rough feeling or asymptomatic. The white tongue may also be caused by abnormal shedding of the cuticle of the tongue papilla on the dorsal mucosa of the tongue, specific need to go to the hospital to do oral and laboratory examination.