Hello, Welcome to HCM, I understand your concern. White patch on tongue which cannot be brushed nor scraped, suggests it s a leukoplakia(refers to a condition where areas of keratosis appear as firmly attached white patches on the mucous membranes of the oral cavity). It is a diagnosis of exclusion(once all other causes are ruled out). Oral leukoplakia more commonly occurs in those who smoke,chew tobacco. Leukoplakia is a premalignant lesion, i.e. a morphologically altered tissue in which cancer is more likely to occur than in its apparently normal counterpart . But the vast majority of oral leukoplakias will not turn malignant. If thats the case it is recommended to recommendation that possible causative factors such as smoking and alcohol consumption be stopped. If the size of patch increases in size, has to br reviewed by physician. Hope this information was useful. Good Luck.