Hypomelanosis of Ito

Last revised by Rohit Sharma on 21 Feb 2024

Hypomelanosis of Ito, also known as incontinentia pigmenti achromians, is the third most frequent phakomatosis, involving a wide spectrum of defects in multiple organ systems.

The prevalence is unknown, being reported as between 1 per 8000 patients in a general pediatric hospital 3 and 1 per 600–700 patients referred to a pediatric neurology service 1.

As a neurocutaneous disease, the skin lesions are remarkable and are present in the first year of life in ~70% of patients. Lesions manifest as hypopigmented zones or spots with irregular borders, sometimes whorls, or linear white streak lines following Blaschko’s lines. Other cutaneous-associated manifestations include café-au-lait spots, cutis marmorata telangiectatica congenita (CMTC), angiomatous nevi, Mongolian blue spots, and nevi of Ota. Iris hypopigmentation is also reported. It is important to note that the disease severity is not correlated with the extent of cutaneous lesions 1.

Changes in hair color, diffuse alopecia and hair with trichorrhexis nodosa are reported as scalp manifestations of this disease.

Extracutaneous manifestations:

The exact cause of hypomelanosis of Ito is unknown with many cases being associated with genetic mosaicism and sporadic gene mutations.

The hypopigmented lesions are the result of a decrease in the number of melanocytes and in the number and size of melanosomes 1.

CT and, more clearly, MRI can demonstrate several abnormalities.

Hypomelanosis of Ito has been associated rarely with vascular anomalies such as Moyamoya syndrome or intracranial arteriovenous malformation.

There is no specific treatment; treatment is based on symptomatology.

This eponymous hypomelanosis was described by Minor Ito (1884-1982), a Japanese dermatologist, in 1952 2.

The most commonly confused diagnosis is with incontinentia pigmenti, a rarer phakomatosis.

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