Hypomelanosis of Ito

Excerpt

Hypomelanosis of Ito (HI), or pigmentary mosaicism, was previously named incontinentia pigmenti achromians. The disease is currently named hypomelanosis of Ito to distinguish this condition from incontinentia pigmenti. HI was first described by Ito in 1952. Hypomelanosis of Ito represents the third most frequent neurocutaneous disease, after neurofibromatosis type 1 and tuberous sclerosis. It is characterized by linear nevoid hypopigmentation along the lines of Blashko located on the limbs and the trunk. This cutaneous pattern appears at birth or in early childhood and usually becomes evident in infancy. The phenotype of HI would be the result of a mosaic dermal abnormality of monogenic or chromosomal origin. HI is a rare neurocutaneous disease with multisystemic involvement. The most common defects involve the central nervous and musculoskeletal systems. Hypomelanosis of Ito is currently a descriptive rather than definitive diagnosis. Blaschkoid or mosaic hypomelanosis is a better descriptive term.