Hypomelanosis of Ito (incontinentia pigmenti achromians). Ophthalmological evidence for somatic mosaicism.

The authors report on a ten-year-old boy with hypomelanosis of Ito. He suffered from epileptic seizures and exhibited typical generalized partial skin hypomelanosis in whorl-like and striated pattern following Blaschko's lines. The fundi showed patchy, mottled hypopigmentations becoming increasingly striated in the periphery with a general orientation to the optic nerve head. This pattern of affection reminds of the retinal findings in carrier women for X-linked ocular albinism. Magnetic resonance imaging revealed multiple small areas of increased relaxation time scattered in the white matter of the brain, which are interpreted as porencephalic cysts. These clinical findings suggest somatic cell mosaicism even though the cytogenetic study was not conclusive.