[Lichen striatus with nail dystrophy in an infant].
Lichen striatus is an acquired eruption that develops in a linear pattern along Blaschko's lines, most commonly on the limbs. It is most often seen in children aged between 3 and 10 years. Nail involvement is uncommon. We report the case of an infant with lichen striatus and nail involvement. A 10-month-old boy was referred for evaluation of acquired onychodystrophy on his right third and fourth fingers present for 2 months. On physical examination, lateral longitudinal ridging and splitting were seen on the right third and fourth fingernails with onychodystrophy. Linear bands of bright pink papules were seen on the inside and outside edges of the third and fourth fingers. Skin biopsy revealed a lymphocytic infiltrate in the superficial dermis with exocytosis and very few dyskeratotic cells, suggesting lichen striatus. Skin and nails lesions resolved spontaneously over 9 months. Nail involvement in lichen striatus is uncommon and is frequently associated with typical skin lesions. Thirty cases have been reported in the literature since 1941. None of the subjects affected was younger than 2-years-old. Nail involvement was more frequent on the fingers, especially the thumb. As in the present case, longitudinal ridging, splitting and thinning with onychodystrophy are common clinical features of nail involvement. The diagnosis of lichen striatus is based on the presence of skin lesions and can be confirmed by biopsy.