Hypomelanosis of Ito

At a glance

Congenital disorder characterized by hypopigmented whorls of skin along the line of Blaschko and associated with multiple other congenital defects, mostly neurologic, skeletal, ophthalmic, hair, and dental anomalies. Seizures, severe developmental delays, and musculoskeletal symptoms (scoliosis) are commonly associated with this condition.

Synonym

Incontinentia Pigmenti Achromians.

History

First described by the Japanese dermatologist Ito in 1952. This heterogeneous condition belongs to a group of mosaic phenotype neurodermatoses.

Incidence

The reported incidence was approximately 1:1,000 new patients consulting a pediatric neurologic service in the general population per year. The incidence is estimated at 1:8,000 to 10,000 amongst children. Females outnumber males by 2.5:1. No ethnic predilection. Hypomelanosis of Ito is present at birth, and patients usually undergo examination in their first or second years of life. Approximately 75% of patients seek care by the time they are aged 2 years. The remaining patients seek medical attention before they are aged 5 years.

Genetic inheritance

Hypomelanosis of Ito is believed to result from chromosomal mosaicism, which could explain why it is so varied in phenotype. Genes on 9q33-qter, 15q11-q13, and Xp11 have been implicated in this syndrome; however, there is no consensus in the literature.

Pathophysiology

The phenotype may result directly from the loss of specific pigmentation genes. A migration defect during central nervous system (CNS) maturation probably accounts for much of the neurologic impairment.

Diagnosis

Characterized by mental retardation, behavioral disturbances, and pigmentary anomalies. Chromosomal mosaicism in epidermal keratinocytes and confined to the hypopigmented epidermis. The normal epidermis contains only normal cells.

Clinical aspects

The disorder is characterized by unilateral or bilateral macular hypopigmented whorls, streaks, and patches that exist from birth. The lines of Blaschko are defined by a pattern determined by different nevoid on the human skin and mucosae. The cause is unknown, and their distributions do not follow nerves, vessels, or lymphatics. In 1901, Blaschko pointed out that the lines described by these conditions not only did not correspond to any known anatomical basis, but also were remarkably consistent both from patient to patient and even from one disease to another. Neurologic impairment (70% of cases) can be severe and present as mental retardation, seizures, neurologic syndromes, cerebellar signs, and hearing loss. Abnormalities of the eyes (strabismus, retinal changes, optic nerve hypoplasia) and the musculoskeletal system (scoliosis, syndactyly) occur in some patients. Other reported abnormalities include cleft palate, hair, nail, teeth, limb, hand and/or foot abnormalities, hemihypertrophy, hypotonia, and face and/or skull anomalies.

Precautions before anesthesia

Measurement of anticonvulsant levels and optimization of anticonvulsant therapy must be obtained. Continue morning dose of anticonvulsants ...