Hypomelanosis of Ito
Hypomelanosis of Ito (HI), 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 since 1 per 8000 patients in a general pediatric hospital 3 to 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 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, nevus marmorata, angiomatous nevi, Mongolian blue spot, and nevus fuscoceruleous 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.
- 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
- HI has occasionally been associated 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.
- hypoplasia or cerebellar atrophy
- focal or generalized cerebral atrophy
- neuronal heterotopias
Head and neck
- cleft lip and palate
- bifid uvula
- nose and ear anomalies
- hypodontia (small teeth)
- partial anodontia (lack of teeth)
- impacted dentition
Treatment and prognosis
There is no specific treatment, which is based on symptomatology.
History and etymology
Was described by Minor Ito (1884-1982), Japanese dermatologist, in 1952 2.
The most commonly confused diagnosis is with incontinentia pigmenti, a rarer phakomatosis.
- neurofibromatosis type 1 (NF1) (von Recklinghausen disease)
- neurofibromatosis type 2 (NF2) (mnemonic)
- tuberous sclerosis (Bourneville-Pringle disease)
- ataxia telangiectasia
- Sturge-Weber syndrome (encephalotrigeminal angiomatosis)
- von Hippel-Lindau disease (retinocerebellar angiomatosis)
- incontinentia pigmenti (Bloch-Sulzberger syndrome)
- basal cell naevus syndrome (Gorlin-Goltz syndrome)
- Wyburn-Mason syndrome (Bonnet-Dechaume-Blanc syndrome)
- encephalocraniocutaneous lipomatosis
- hypomelanosis of Ito
- Nijmegen breakage syndrome
- epidermal naevus syndrome
- neurocutaneous melanosis
- progressive facial hemiatrophy (Parry-Romberg syndrome)
- PHACE syndrome
- Cowden disease/COLD syndrome
- Gomez-Lopez-Hernandez syndrome
- 1. Pascual-Castroviejo I, Roche C, Martinez-Bermejo A et-al. Hypomelanosis of ITO. A study of 76 infantile cases. Brain Dev. 1998;20 (1): 36-43. Pubmed citation
- 2. ITO M. Studies on melanin. Tohoku J. Exp. Med. 2004;55 (Suppl. 1): 1-104. Pubmed citation
- 3. Zvulunov A, Esterly NB. Neurocutaneous syndromes associated with pigmentary skin lesions. J. Am. Acad. Dermatol. 1995;32 (6): 915-35. Pubmed citation