White sponge nevus (WSN) is a rare oral mucosal lesion first described by Cannon in 1935, characterized as benign leukokeratotic lesion of early onset with periods of remission and exacerbation. It is usually asymptomatic, although pruritus, burning, and pain have been reported following irritating stimuli.WSN is inherited as an autosomal dominant trait with wide variability of expression and h...

Keratin 16 (KRT16 in human, Krt16 in mouse), a type I intermediate filament protein, is constitutively expressed in epithelial appendages and is induced in the epidermis upon wounding and other stressors. Mutations altering the coding sequence of KRT16 cause pachyonychia congenita (PC), a rare autosomal dominant disorder characterized by hypertrophic nail dystrophy, oral leukokeratosis, and pal...

Dear Editor, Pachyonychia congenita (PC) is an ultra-rare hereditary skin disorder primarily characterized by severe, painful and highly debilitating plantar keratoderma, variable hypertrophic nail dystrophy, epidermal cysts, leukokeratosis and other features. PC is caused by heterozygous dominant-negative mutations in any one of five keratin genes, KRT6A, KRT6B, KRT6C, KRT16 or KRT17 (encoding...

We report the case of an 11-year-old girl who presented to our multidisciplinary pain center with the chief complaint of chronic bilateral foot pain because of a rare congenital keratin disorder. This patient had been diagnosed with pachyonychia congenita, an extremely rare genetic disorder primarily affecting the skin and nails. The child had bilateral foot pain for years because of the charac...