Pachyonychia Congenita - Can a Specific Phenotype be a Clue to a Genetic Defect? - a Case Report and Literature Review

Pachyonychia congenita (PC) is a rare inherited disorder of keratinization characterized by hypertrophic nail dystrophy, painful palmoplantar blisters, cysts, follicular hyperkeratosis and oral leukokeratosis. These pathological clinical features are resulting from mutations in keratin proteins including KRT6A, KRT6B, KRT6C, KRT16, and KRT17. We present a 6-year-old girl with hypertrophic nail dystrophy, follicular hyperkeratosis, circumscribed plantar keratoderma and oral leukokeratosis. The features were consistent with the diagnosis of PC. The patient has been registered in the International Pachyonychia Congenita Research Registry (IPCRR) and is waiting for a detailed genetic analysis. The IPCRR has contributed to publication of numerous papers which emphasized the importance of the mutation type affecting various clinical presentations of PC. Based on recent data, a new classification system has been developed for PC, and it is gradually replacing the earlier classifications. It is based almost exclusively on the mutated genes. In this report we have raised the hypothesis that distinctive clinical features may be highly suggestive of a specific keratin mutation.