<prompt> White persistent patch in mouth indicatesMucormycosisStreptococcal infectionErythroplakiaAll  <response>: Ans. b Streptococcal infection. Ref. Diseases of ENT by Bhargava 6th ed. 211MembraneWhite patch on the tongue or oral mucosa is seen in: Leucoplakia Premalignant Lichen planus Premalignant Behcets syndrome Streptococcal infection Diphtheria Dirty grey patch Vincents angina Syphilis Moniliasis Oral thrush or Candidiasis Aphthous ulcers with slough at the base Viral pharyngitis Oral submucous fibrosis and erythroplakia are other premalignant oral lesions. 