[Incontinentia pigmenti].

Incontinentia pigmenti (IP) is a hereditary syndrome characterized by specific skin lesions occurring mostly during the neonatal period (96% of the cases before 6 weeks of age). These skin lesions have four steps of evolution: inflammatory or erythemato-bullous stage (very often associated with peripheral blood hyper-eosinophilia), proliferative or verruco-lichenoid stage, pigmentary or terminal stage characterized by "fountain" or "firework" features (with a picture of pigmentary incontinence at histological examination), sometimes there is a fourth stage referred to as "involutive". Ocular and neurological involvement is the main determinant in the prognosis. Eye lesions include corneal flecks, cataracts, uveitis or optical atrophy with retrolental fribroplasia. The neurological involvement includes pyramidal syndrome, cerebral ataxia, microcephalia, and mental retardation. The disease has mainly an X-linked dominant transmission and is usually lethal for males. Rare cases are observed in boys, some being associated with Klinefelter syndrome. Research is ongoing to identify the IP gene on the X chromosome. In the family form of IP, the gene has been located on chromosome Xq28, which allows prenatal diagnosis using trophoblast biopsy.