Pachyonychia congenita type I with severe oral leukokeratosis

Pachyonychia congenita (pc) is a rare autosomal dominant keratin disorder that affects a number of ectodermal structures including the nails and palmoplantar skin,and often involves the oral mucosa,tongue,larynx,teeth and hair. clinical features are usually present at birth or early infancy. there are two main subtypes of pc. fingernail thickening and oral keratosis are more common and severe in pc-1 and cystic lesions,hair abnormalities,natal teeth and pili torti are more common in pc-2. we report the case of a 6-year-old boy with pc-1 presenting with severe and painful oral leukokeratosis and extensive caries.