Hypomelanosis of Ito

In 1952, Ito reported a female patient with a widespread, i. Recognizable at birth (54%) symmetric pattern of depigmented whorls and streaks, naming ii. Visible during childhood (70%) it achromians, because the distribution b. No signs of inflammation or verrucous changes char- of the depigmented lesions is the negative image of the hyper- acteristically seen in incontinentia pigmenti pigmented streaks of incontinentia pigment. Hypomelanosis of c. Hypopigmented lesions Ito (HI) is a relatively common disorder with a frequency of i. Typical phenotype 1 in 8000–10,000 patients in a general pediatric hospital and a) Cutaneous pattern: essentially the reverse of 1 in 1000 patients in a pediatric neurology service. the third stage of incontinentia pigmenti b) Bilateral or unilateral whirls, patches, and GENETICS/BASIC DEFECTS streaks corresponding to the lines of Blaschko, often showing a midline cutoff 1. Inheritance c) Eruption not preceded by any inflammatory a. Sporadic occurrence in nearly all cases with no affected lesions (unlike incontinentia pigmenti) sibs or parents ii. Unilateral skin lesions contralateral to the side of i. Result of a de novo postzygotic mutation brain malformation in patients with HI and ii. Mutation can only survive in a mosaic state hemimegalencephaly b. Only a few cases with possible genetic inheritance iii. Wood lamp useful in demonstrating hypopig- reported mented lesions in persons with fair skin i. X-linked dominant inheritance iv. Atypical phenotype: checkerboard pattern, zos- ii. Autosomal dominant teriform, dermatomal, or plaquelike arrangement iii. Autosomal recessive d. Nonspecific skin lesions (20–40%) 2. Pathogenesis i. Café-au-lait spots a. Chromosome abnormalities (52%) ii. Persistent mongolian blue spots i. Mosaicism leading to generation of two cell lin- iii. of Ota eages producing patterns of hypopigmented and iv. Nevus marmoratus and angiomatous nevi hyperpigmented skin v. Soft fibroma ii. Balanced X/autosome translocations vi. Pilomatrixoma iii. Supernumerary X chromosome/ring fragment vii. Aplasia cutis iv. Ring chromosomes (10, 14, 22) viii. Atopic dermatitis v. Mosaic triploidy 2. Hair/nail/sweat gland anomalies vi. Mosaic trisomies (8, 13, 14, 18, 22) a. Focal hypertrichosis vii. Mosaic translocations b. Slow growth viii. Mosaic deletions c. Diffuse alopecia ix. Autosomal deletions and duplications involving d. Coarse, curly hair chromosomes 7, 12, 13, 14, 15, and 18 e. Trichorrhexis b. X chromosome abnormalities f. Widows peak i. Inactivation g. Generalized hirsutism ii. Activation h. Facial hypertrichosis iii. Mosaicism i. Low hairline 3. A descriptive term rather than a true syndrome j. Ungual hypoplasia a. Suggested by the pattern of chromosomal aberrations k. Hypohidrosis corresponding to hypopigmented areas and the polymorphic nature of the disease 3. Associated extracutaneous anomalies (75%) b. A term used for a phenotype a. CNS anomalies i. Presence of linear streaks lighter than the patient’s i. Mental retardation (50–75%) background skin color, extending around the ii. Seizures (50%) trunk and down the long axes of the extremities, iii. Autistic behavior (11%) roughly following the lines of Blaschko iv. Microcephaly ii. Association with systemic findings v. Hypotonia vi. Hyperkinesia CLINICAL FEATURES vii. Ataxia 1. Cutaneous symptoms viii. Deafness a. Onset ix. Hemimegalencephaly

528 HYPOMELANOSIS OF ITO 529

x. Brain tumors (medulloblastoma, choroid plexus 4. Diagnostic criteria (Ruiz-Maldonado et al., 1992) papilloma) a. Sine qua non criterion: congenital or early acquired b. Ophthalmological abnormalities (20%) nonhereditary cutaneous in linear i. Microphthalmia streaks or patches involving more than two body ii. Ptosis segments iii. Nonclosure of the upper lid b. Major criterion iv. Symblepharon i. One or more nervous system anomalies v. Dacryostenosis ii. One or more musculoskeletal anomalies vi. Strabismus c. Minor criterion vii. Nystagmus i. Two or more congenital malformations other than viii. Myopia nervous system or musculoskeletal anomalies ix. Hyperopia ii. Chromosomal anomalies x. Astigmatism d. Definitive diagnosis: sine qua non criterion plus one xi. Amblyopia or more major criteria or two or more minor criteria xii. Megalocornea e. Presumptive diagnosis: sine qua non criterion alone xiii. Corneal opacification or in association with one minor criterion xiv. Cataracts xv. Iridal heterochromia DIAGNOSTIC INVESTIGATIONS xvi. Scleral xvii. Heterochromia of the iris 1. Cytogenetic investigation xviii. Optic atrophy a. Peripheral blood karyotyping indicated especially xix. Striated patchy hypopigmented fundi when systemic manifestations are present xx. Retinal detachment b. Fibroblast karyotyping by sampling the dark and light c. Dental abnormalities skin for demonstrating mosaicism or chromosomal i. Defective dental implantation abnormalities ii. Conical teeth c. Presence of a wide variety of karyotypic abnormalities iii. Partial anodontia 2. Histopathology iv. Dental dysplasia/hypoplasia a. Decreased numbers of v. Defective enamel b. Decreased numbers and size of pigmented melanosomes vi. Hamartomatous dental cusps c. Neuropathological features d. Skeletal defects i. Polymicrogyria i. Short stature ii. Disarray of cortical lamination ii. Facial and limb asymmetry (hemihypertrophy) iii. Heterotopic neurons in the white matter iii. Pectus carinatum or excavatum iv. Giant cells iv. Scoliosis 3. CT and MRI of the brain v. Syndactyly a. White matter abnormalities somewhat predictive of a vi. Polydactyly poor neurological outcome vii. Brachydactyly b. Neuroblast migration viii. Clinodactyly i. Heterotopia e. Congenital heart defect ii. Pachygyria i. Tetralogy of Fallot iii. Polymicrogyria ii. Pulmonary stenosis c. Localized or generalized cerebral atrophy iii. Ventricular septal defect d. Cerebral hemiatrophy iv. Atrial septal defect e. Hemimegalencephaly v. Incomplete right bundle branch block f. Other rare anomalies vi. Cardiomegaly of unknown etiology i. Noncommunicating hydrocephalus f. Abdomen/gastrointestinal anomalies ii. Megacisterna magna i. Diastasis recti iii. Arteriovenous malformation ii. Hepatomegaly iv. Cerebellar hypoplasia (hemispheres and vermis) iii. Segmental dilation of the colon v. Brainstem hypoplasia iv. Diaphragmatic, umbilical, and inguinal hernias vi. Brain tumors g. Genitourinary anomalies 4. Radiography for musculoskeletal anomalies i. Hypospadias 5. EEG for seizures ii. Micropenis iii. Single kidney GENETIC COUNSELING iv. Urethral duplication 1. Recurrence risk v. Cryptorchidism a. Patient’s sib: not increased unless a parent shows vi. Precocious puberty chromosomal abnormalities vii. Gynecomastia b. Patient’s offspring: viii. Asymmetrical breasts i. Not increased unless the patient has chromosomal ix. Nephritis abnormalities 530 HYPOMELANOSIS OF ITO

ii. Guarded counseling in women with a phenotype Nehal KS, PeBenito R, Orlow SJ: Analysis of 54 cases of hypopigmentation similar to HI who have nonmosaic balanced X; and along the lines of Blaschko. Arch Dermatol 132:1167–1170, 1996. autosome translocations Ohashi H, Tsukahara M, Murano I, et al.: Pigmentary dysplasias and chromo- 2. Prenatal diagnosis: undetermined for affected mother somal mosaicism: report of 9 cases. Am J Med Genet 43:716–721, 1992. who has a specific type of chromosome abnormality Ono J, Harada K, Kodaka R, et al.: Regional cortical dysplasia associated with 3. Management suspected hypomelanosis of Ito. Pediatr Neurol 17:252–254, 1997. a. Early intervention programs including physical, occu- Pascual-Castroviejo I, Lopez-Rodriguez L, de la Cruz Medina M, et al.: Hypomelanosis of Ito. Neurological complications in 34 cases. Can J pational, and speech therapies Neurol Sci 15:124–129, 1988. b. Special education Pascual-Castroviejo I, Roche C, Martinez-Bermejo A, et al.: Hypomelanosis of c. Seizure control ITO. A study of 76 infantile cases. Brain Dev 20:36–43, 1998. d. Surgical treatment of cataracts and retinal detachment Ritter CL, Steele MW, Wenger SL, et al.: Chromosome mosaicism in hypome- lanosis of Ito. Am J Med Genet 35:14–17, 1990. Ross DL, Liwnicz BH, Chun RW, Gilbert E: Hypomelanosis of Ito (incontinen- REFERENCES tia pigmenti achromians)—a clinicopathologic study: macrocephaly and De Menezes MS: Hypomelanosis of Ito. EMedicine, 2002. http://www. gray matter heterotopias. Neurology 32:1013–1016, 1982. emedicine.com Rott H-D, Lang GE, Huk LW, et al.: Hypomelanosis of Ito (incontinentia pig- Flannery DB: Pigmentary dysplasias, hypomelanosis of Ito, and genetic menti achromians). Ophthalmological evidence for somatic mosaicism. mosaicism. Am J Med Genet 35:18–21, 1990. Ophthalmic Paediatr Genet 11:273–279, 1990. 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Happle R: Pigmentary patterns associated with human mosaicism: a proposed Ruiz-Maldonado R, Toussaint S, Tamayo L, et al.: Hypomelanosis of Ito: diag- classification. Eur J Dermatol 3:170–184, 1993. nostic criteria and report of 41 cases. Pediatr Dermatol 9:1–10, 1992. Harre J, Millikan LE: linear and whorled pigmentation. Int J Dermatol Steiner J, Adamsbaum C, Desguerres I, et al.: Hypomelanosis of Ito and brain 33:529–537, 1994. abnormalities: MRI findings and literature review. Pediatr Radiol Hatchwell E, Robinson D, Crolla JA, et al.: X inactivation analysis in a female 26:763–768, 1996. with hypomelanosis of Ito associated with a balanced X;17 transloca- Sybert VP, Pagon RA, Donlan M, Bradley CM: Pigmentary abnormalities and tion: evidence for functional disomy of Xp. J Med Genet 33:216–220, mosaicism for chromosomal aberration: association with clinical features 1996. similar to hypomelanosis of Ito. J Pediatr 116:581–586, 1990. Ishikawa T, Kanayama M, Sugiyama K, et al.: Hypomelanosis of Ito associated Sybert VP, Pagon RA: Hypomelanosis of Ito in a girl with plexus papilloma and with benign tumors and chromosomal abnormalities: a neurocutaneous translocation (X;17) [letter]. Hum Genet 93:227, 1994. syndrome. Brain Dev 7:45–49, 1985. Sybert VP: Hypomelanosis of Ito: a description, not a diagnosis. J Invest Ito M: A singular case of naevus depigmentosus systematicus bilateralis. Jpn J Dermatol 103(5 Suppl):141S–143S, 1994. Dermatol 61:31–32, 1951. Tagawa T, Futagi Y, Arai H: Hypomelanosis of Ito associated with hemimega- Koiffmann CP, de Souza DH, Diament A, et al.: Incontinentia pigmenti achro- lencephaly: a clinicopathological study. Pediatr Neurol 17:180–184, 1997. mians (hypomelanosis of Ito, MIM 146150): Further evidence of Urgelles E, Pascual-Castroviejo I, Roche C, et al.: Arteriovenous malformation Localization at Xp11. Am J Med Genet 46:529–533, 1993. in hypomelanosis of Ito. Brain Dev 18:78–80, 1996. 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Fig. 1. Two children with hypomelanosis of Ito showing hypopigmented skin lesions in a characteristic distribution of whirls and streaks on the trunk and limbs. The first patient has 49,XXXXY.