pachyonychia congenital (pc) is a rare autosomal dominant genodermatosis characterized hyperkeratosis affecting the nails and palmoplantar areas, oral leukokeratosis, and cystic lesions. a 39-year-old woman with pc type 1 (jadassohn-lewandowsky syndrome) and b-cell lymphoma is described. no similar disorders or parental consanguinity were found in her family. typical features of pc developed si...