Hypomelanosis of Ito

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

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

As a neurocutaneous disease, the skin lesions are remarkable and are present in the first year of age in ~70%. Being represented 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 cutaneous lesion extension 1.

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

Extracutaneous manifestations:

  • mental retardation 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 assiciation with benign tumours, including
    • mature cystic teratoma
    • mature sacrococcygeal dysembryonal tumour
    • choroid plexus papilloma
    • dental hamartomatous tumours

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 referred as a  result of a decrease in the number of melanocytes and in the number and size of melanosomes 1.

CT and mostly MRI can demonstrate several abnormalities.

HI has been associated rarely with vascular anomalies as Moyamoya syndrome or intracranial arteriovenous malformation.

There is no specific treatment, which is based on symptomatology.

Was described by Minor Ito (1884-1982), Japanese dermatologist, in 1952 2.

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

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Article information

rID: 32151
Section: Syndromes
Tag: cases
Synonyms or Alternate Spellings:
  • Incontinentia pigmenti achromians
  • Ito hypomelanosis

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