The hallmark of hypomelanosis of Ito or incontinentia pigmenti acromians is the presence of a well-defined area of hypopigmented skin along the lines of Blaschko (Figure 309.1 [A]). The hypopigmentedareasmayinvolve any body parts (large or small, linear, vorticose, or square). Wood lamp examination may be needed to demonstrate the hypopigmented areas. The skin histopathological findings are similar to those encountered in tuberous sclerosis. Hypomelanosis of Ito may be associated with nervous system, ocular, musculoskeletal, and vascular abnormalities. The most frequent neurological problems in the neonatal period are seizures and hypotonia, but arthrogryposis may also occur. Magnetic resonance imaging of the brain may reveal hydrocepahlus (Figure 309.1 [B]) or atrophy. Hypomelanosis of Ito appears to be an etiologically hetereogenous physical finding. Karyotyping of the affected skin is indicated because of the possibility of chromosomal mosaicism.

A	B

Figure 309.1.— Hypomelanosis of Ito. [A] Well-delineated hypopigmented area and arthrogryposis of the arms. [B] Magnetic resonance imaging of the same patient demonstrating significant hydrocephalus.