Hypomelanosis of Ito

Hypomelanosis
of Ito with central nervous system manifestation. FLAIR axial image showing hyperintensities in deep periventricular white matter bilaterally with small hypointense cysts within affected white matter.
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Hypomelanosis
of Ito with central nervous system manifestation. FLAIR axial image showing hyperintensities in deep periventricular white matter bilaterally with small hypointense cysts within affected white matter.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. FLAIR coronal image showing hyperintensities in deep periventricular white matter bilaterally with small hypointense cysts within affected white matter.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. T2W axial image showing hyperintensities in deep periventricular white matter with small hyperintense cysts.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. T2W axial image showing hyperintensities in deep periventricular white matter with small hyperintense cysts.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. T2W axial image showing hyperintensities in deep periventricular white matter with small hyperintense cysts.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. T1W axial image showing hypointense cysts in deep periventricular white matter.
www.eurorad.org • CC by-nc-sa-4.0
Hypomelanosis
of Ito with central nervous system manifestation. T1W sagittal image showing hypointense cysts in deep periventricular white matter.
www.eurorad.org • CC by-nc-sa-4.0
nicht verwechseln mit: Incontinentia pigmenti
Radiopaedia • CC-by-nc-sa 3.0 • de

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.

Epidemiology

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

Clinical presentation

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 spot, and nevus 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 .

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

Extracutaneous manifestations:

  • intellectual disability and epilepsy: seizures commonly appear early and generally are refractory to anticonvulsant drugs
  • a variety of non-specific ocular alterations
  • dental: defective dental implantation, conical teeth, partial anodontia, and hypodontia
  • musculoskeletal disorders, such as hypotonia
  •  occasional association with benign tumors, including

Pathology

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 .

Radiographic features

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

CNS

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

Head and neck
Musculoskeletal

Treatment and prognosis

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

History and etymology

Was described by Minor Ito (1884-1982), Japanese dermatologist, in 1952 .

Differential diagnosis

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