A case of pachyonychia congenita with unusual manifestations: an unusual type or a new syndrome?

A 30-year-old man presented with lesions on his oral mucosa and soles. There were no similar complaints in his family members. The dermatological examination revealed follicular hyperkeratosis on his trunk and upper extremities and flesh-colored, firm cystic lesions on his axillae. He had focal, painful, hyperkeratotic areas sited particularly on both his soles and palms. In addition to these, leukokeratosis and ulcerative areas on buccal, labial mucosa, tongue, and at corners of the mouth, and complete loss of teeth was observed. The proximal layering was revealed on all of his nails. The laboratory investigations produced normal results except the deficiency of immunoglobulin A. The psychiatric examination revealed mild mental retardation. Keratin gene (KRT6a, KRT6b, KRT16, and KRT17) mutations for pachyonychia congenita were negative. He got removable dental prosthesis because of inadequate alimentation. Squamous cell cancer developed on lower lip mucosa during follow-up. We present an individual who had different nail dystrophy, epidermal cysts, mental retardation, blepharitis, complete loss of teeth, and negative keratin gene mutations for pachyonychia congenita and developed squamous cell cancer on the oral leukokeratosis lesions. We think that the present case may be an unusual new type of pachyonychia congenita.