Hypomelanosis of Ito (Incontinentia pigmentosa achromians)

Page most recently updated 7 September 2026

This page focuses on the reported psychiatric associations, which may be the initial presenting manifestation, and on other clinical features that may assist the psychiatrist or primary care physician in identifying the underlying diagnosis, considered through the lenses of the diagnostic lenses framework.

Hypomelanosis of Ito (incontinentia pigmentosa achromians) is a rare neurocutaneous disorder affecting multiple organ systems. It usually occurs sporadically, without a family history. It is usually associated with genetic mosaicism (genetic changes that occur in some cells of the body but not others), resulting in different populations of skin cells. As these cells follow characteristic embryonic migration pathways known as the lines of Blaschko, a pigment-producing defect in one population can become visible as whorled or linear areas of hypopigmentation. A distinctive presentation may include the combination of characteristic whorled or linear areas of hypopigmentation following the lines of Blaschko, intellectual impairment, and seizures, particularly when accompanied by ocular or skeletal abnormalities.

It can present with psychiatric features such as autism spectrum disorder (ASD), behavioural difficulties, and sleep disturbance. ADHD and psychotic symptoms have also been reported, although these are less well established. Neuropsychiatric manifestations are usually recognised during childhood, and late-onset new psychiatric presentations in adulthood are not typical.

From a morphologic lens perspective, other features include (but are not limited to):

  • Macrocephaly

  • Epicanthus

  • Thick vermilion

Other characteristic features include hypotonia, ataxia, and speech or language difficulties. Structural neurological abnormalities may include cortical malformations, hemimegalencephaly, abnormalities of neuronal migration, cerebral atrophy, and agenesis of the corpus callosum. Other manifestations may include ocular abnormalities, hearing impairment, scoliosis or other skeletal asymmetry, and dental abnormalities.

Early diagnosis is important to identify neurological, developmental, ocular, musculoskeletal, and other extracutaneous complications; to provide appropriate developmental and educational support; and to allow surveillance and management of seizures and other potentially significant complications. A normal blood genetic or chromosomal test does not exclude the diagnosis, because the underlying mosaic abnormality may be confined to affected tissues such as skin.

Selected references and further reading — Morphologic lens

Jones KL, Jones MC, del Campo M. Smith's recognizable patterns of human malformation. 8th ed. Philadelphia: Elsevier; 2021.

Reardon W. The bedside dysmorphologist: a guide to identifying and assessing congenital malformations. 2nd ed. Oxford: Oxford University Press; 2016.

Allanson JE, Biesecker LG, Carey JC, Hennekam RCM. Elements of morphology: introduction. Am J Med Genet A. 2009;149A(1):2-5. doi:10.1002/ajmg.a.32601.

Hennekam RCM, Biesecker LG, Allanson JE, Hall JG, Opitz JM, Temple IK, Carey JC; Elements of Morphology Consortium. Elements of morphology: general terms for congenital anomalies. Am J Med Genet A. 2013;161A(11):2726-2733. doi:10.1002/ajmg.a.36249.