Parents of a 5-year-old child noted irregular colour of the child's back of tongue and consulted a pedodontist about this. Objectively: the oral cavity is sanitized, DF index = 4, dorsal and lateral surfaces of tongue have area of desquamating epithelium bordering upon areas of hypertrophy and increased corni-fication of filiform papillae. The child has a history of being allergic to some foodstuffs. What is the clinical diagnosis?