Hypomelanosis of Ito

Congenital disorder characterized by hypopigmented whorls of skin along the line of Blaschko and associated with multiple other congenital defects, mostly neurologic, skeletal, hair, and dental anomalies.

Incontinentia Pigmenti Achromians.

First described by the Japanese dermatologist Ito, this heterogeneous condition belongs to a group of mosaic phenotype neurodermatoses.

Incidence was approximately 1:1000 new patients consulting a pediatric neurologic service, or 1:8000-10,000 unselected patients in a children's hospital. Females outnumber males by 2.5:1. No ethnic predilection.

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.

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.

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.

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 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.

Measurement of anticonvulsant levels and optimization of anticonvulsant therapy must be obtained. Continue morning dose of anticonvulsants until the day of surgery. Document neurologic deficits. Evaluate respiratory function in the presence of scoliosis (effort tolerance, arterial blood gas, lung function tests, chest radiograph). Assess cardiac function if there is a long-standing history of respiratory impairment.

In the presence of significant facial anomalies, evaluate carefully for difficulties with airway management. Triggers that potentiate occurrence of seizures are to be avoided. Preoperative intravenous seizure medication might be indicated during long surgical procedure or important fluid shift. A regional technique as the sole anesthetic may be difficult in view of the patient's mental retardation, behavioral disturbances, and deformities of the spine. No specific contraindications to regional anesthesia in patients with preexisting neurologic syndromes, but careful counseling of patients and detailed documentation of deficits should be done.

Premedication must be avoided in presence of significant airway problem, obstruction, sleep apnea, or respiratory disease. Triggers that potentiate occurrence of seizures are to be avoided (enflurane with hypocapnia, methohexital, ketamine). Larger doses of some anesthetic medications (e.g., vecuronium) may be required on chronic phenobarbital therapy because of induction of hepatic enzymes.

Incontinentia Pigmenti: Genetic disease involving the skin, hair, teeth, and central nervous system. Caused by a defective NEMO gene. Gene map locus is Xq28. X-linked dominance with lethality in males.