Hypomelanosis of Ito--a nonspecific marker of somatic mosaicism: report of case with trisomy 18 mosaicism.

We report on a patient with hypomelanosis of Ito (HI), developmental delay, recurrent pneumonia, and facial asymmetry. Chromosome analysis done on blood and on one of three skin biopsies showed trisomy 18 mosaicism. This is the first report of HI associated with trisomy 18 mosaicism. This neuroectodermal disorder appears to be a nonspecific manifestation of chromosome mosaicism.