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Pediatric Hypomelanosis of Ito Differential Diagnoses

  • Author: Camila K Janniger, MD; Chief Editor: Dirk M Elston, MD  more...
Updated: Jun 24, 2016

Diagnostic ConsiderationsLinear and whorled nevoid hypermelanosisNevus depigmentosusIncontinentia pigmentiVitiligoPityriasis alba

Many other skin pigmentary abnormalities may be associated with systemic and neurological abnormalities. In tuberous sclerosis, the lesions are round, oval, or in the shape of an ash leaf and do not follow the lines of Blaschko.[19]

These conditions are characterized by brown pigmentation and hypopigmentation in streaks and whorls, which follow the lines of Blaschko. Because determining whether the darker or lighter skin color is the normal one is difficult, Sybert suggests that differentiating the dermatological features of linear and whorled nevoid hypermelanosis from the ones found in hypomelanosis of Ito (HI) is virtually impossible.[20] In patients with linear and whorled nevoid hypermelanosis, the lesions appear in infancy and gradually spread though the body. This feature is not helpful in the differentiation from hypomelanosis of Ito, in which skin lesions are present at birth in more than one half of patients. Linear and whorled nevoid hypermelanosis are not associated with systemic abnormalities, unlike in hypomelanosis of Ito.

Nevus depigmentosus is characterized by hypochromic lesions in streaks and whorls, which also follow the lines of Blaschko. The hypochromic lesions tend to be circumscribed and are present at birth, changing little thereafter. Systemic abnormalities are rare in nevus depigmentosus.

Incontinentia pigmenti (IP) is a condition seen mostly in girls; thus, X-linked dominant transmission is postulated. Patients with IP frequently have systemic involvement, similar to the involvement in patients with hypomelanosis of Ito, including CNS manifestations. In patients with IP, cutaneous lesions undergo 3 stages, which may overlap.

The first phase is characterized by vesiculobullous lesions that appear in a linear array (with no dermatomal distribution) and are present from birth or develop in the first 2 weeks of life in 90% of patients. Vesicles are proximal in the limbs, are located in flexor surfaces, and contain eosinophils. This first phase may last days to months. Between the second and sixth week of life, the vesicles become pustular, verrucous, or keratotic, marking the second phase. In this phase, the lesions tend to be more distally and dorsally prominent in the limbs.

The second phase, during which hypopigmentation and skin atrophy develop, usually lasts for months.

During the third phase, hyperpigmentation of lesions is observed, peaking from 12-26 weeks of life. The dermatological appearance involves streaks, whorls, macules, and flecks. The color of the lesions is chocolate-brown or tan. Some patients are born with lesions already in the third phase. This phenomenon is thought to be caused by in utero onset of the inflammatory process.

The term incontinentia pigmenti is used because melanin is not observed in the epidermis but is present in the dermis, as if it had leaked or dropped into the deeper layer of the skin; thus, the epidermis is incontinent of melanin. This incontinence of melanin is not observed in the skin of patients with hypomelanosis of Ito. Alopecia may be observed in one third of patients with IP.

Neuropathologically, patients with IP may show neuroblast migration disturbances, such as polymicrogyria. Inflammatory and destructive alterations often accompany IP lesions, which is a pattern often missing in hypomelanosis of Ito. The reader is referred to Rosman, 1987, for a review of the clinical picture of incontinentia pigmenti.[21]

Segmental vitiligo may be a consideration.[22, 23]

Pityriasis alba, a localized hypopigmented disorder, has many existing clinical variants, some of which may require distinction from IP.[24]

Differential Diagnoses

Contributor Information and Disclosures

Camila K Janniger, MD Clinical Professor of Dermatology, Clinical Associate Professor of Pediatrics, Chief of Pediatric Dermatology, Rutgers New Jersey Medical School

Camila K Janniger, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.


Marcio Sotero de Menezes, MD Clinical Associate Professor, Department of Neurology, Division of Pediatric Neurology, Seattle Children's Hospital, University of Washington School of Medicine; Director, Pediatric Neuroscience Center and Genetic Epilepsy Clinic, Swedish Neuroscience Institute

Marcio Sotero de Menezes, MD is a member of the following medical societies: American Academy of Neurology, American Epilepsy Society

Disclosure: Received salary from Novartis for speaking and teaching; Received salary from Cyberonics for speaking and teaching; Received salary from Athena diagnostics for speaking and teaching.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Robert A Schwartz, MD, MPH Professor and Head of Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, Rutgers New Jersey Medical School; Visiting Professor, Rutgers University School of Public Affairs and Administration

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, New York Academy of Medicine, American Academy of Dermatology, American College of Physicians, Sigma Xi

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

Kevin P Connelly, DO Clinical Assistant Professor, Department of Pediatrics, Division of General Pediatrics and Emergency Care, Virginia Commonwealth University School of Medicine; Medical Director, Paws for Health Pet Visitation Program of the Richmond SPCA; Pediatric Emergency Physician, Emergency Consultants Inc, Chippenham Medical Center

Kevin P Connelly, DO is a member of the following medical societies: American Academy of Pediatrics, American College of Osteopathic Pediatricians, American Osteopathic Association

Disclosure: Nothing to disclose.

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Hypomelanosis of Ito on the torso.
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