Hypomelanosis of Ito

What is Hypomelanosis of Ito?

Hypomelanosis of Ito (HI), also known as pigmentary mosaicism, was earlier named incontinentia pigmenti achromians. It’s been renamed Hypomelanosis of Ito, to make it distinct from incontinentia pigmenti. This disease was first spotted by a doctor named Ito in 1952. Hypomelanosis of Ito is commonly seen as the third most occurring disease that affects both the nerves and the skin, following neurofibromatosis type 1 and tuberous sclerosis—two other conditions that impact the nerves and skin.

The main feature of Hypomelanosis of Ito is the presence of light-colored or less pigmented streaks or lines on the skin, specifically on the limbs and the trunk. These lines follow a pattern known as Blaschko’s lines. Usually, it’s visible at birth or early childhood and becomes more obvious during infancy.

It is thought that this condition arises from particular chromosomal changes or genetic issues that affect the skin cells in different parts of the body, explaining the mosaic or patchy pattern seen. Hypomelanosis of Ito is a rare condition that not only affects the skin but can also have impacts on other systems in the body including the brain and muscles.

Currently, Hypomelanosis of Ito is seen as a description of the observed symptoms rather than a conclusive diagnosis. This is because it has a variety of different possible causes and effects. Therefore, ‘Blaschkoid or mosaic hypomelanosis,’ which points to the distinct pattern and lack of pigmentation of the skin, is often used as a more descriptive term.

What Causes Hypomelanosis of Ito?

The cause of Hypomelanosis of Ito, a skin condition characterized by lighter patches of skin, remains unknown. This condition has been observed to occur within families, leading to suggestions that it might be due to some unusualness in the chromosomes (parts of the cell that contain our genes). Various ways of how the condition might be passed down from parent to child, such as X-linked (where the condition is connected to the X-chromosome), autosomal-dominant (where if you inherit the affected gene from just one parent you’ll get the condition), and autosomal-recessive (where two copies of an abnormal gene must be present for the condition to develop), have been proposed.

However, until now, there is no solid evidence that the condition is inherited. Most cases appear randomly with no family history. Some researchers have observed differences in the number or structure of some people’s chromosomes (also known as chromosomal mosaicism), and the rearrangement of parts between nonhomologous chromosomes (called chromosomal translocations). But these findings aren’t consistent and don’t explain all cases of Hypomelanosis of Ito.

Risk Factors and Frequency for Hypomelanosis of Ito

HI, or Hypomelanosis of Ito, is a rare condition that is present from birth. The actual number of people affected by this condition is not known. In one Italian city, it’s estimated that about 1 in every 7540 newborns has this condition. Generally, about 1 in every 82,000 people may have it. In Spain, about 1 in every 8,000 to 10,000 new patients admitted to a children’s hospital were diagnosed with HI. It’s considered the third most common condition that affects both the nerves and skin.

People of all genders can have HI, but it’s more common in women than men, with the ratio being about 2.5 to 1.
People of all races can have HI. However, the skin abnormalities associated with HI are easier to spot on darker skin.
The signs of HI are usually noticeable at birth. In about 25% of cases, the symptoms might appear during their early childhood.

Signs and Symptoms of Hypomelanosis of Ito

HI lesions are a type of skin issue that is similar to what is seen in a condition known as incontinentia pigmenti. They show as light patches on the skin that follow patterns known as the lines of Blashko. These lines reflect paths that skin cells traveled during fetal development. These light patches can be on one or both sides of the body and can either be scattered or cover large areas. They generally do not appear on the palms of hands, soles of feet, or inner body cavities. They can appear anywhere on the body, but are less common on the head.

The light skin patches can sometimes only become noticeable a few months after birth or after the skin has been exposed to the sun. The increased contrast with healthy skin makes them more apparent. Over time, especially in adulthood, they may fade. The skin in these areas does not completely lack pigment, but has less than normal. Other skin issues may also be present such as café-au-lait spots, hardening and thickening of the skin (morphea), scaly skin (ichthyosis), blue or bluish-grey skin discolorations (Nevus of Ota and Mongolian blue spots), tumor of the hair follicle (pilomatrixoma), soft skin growths (soft fibroma), and skin irritation (atopic dermatitis).

Beyond skin issues, other symptoms are found in about 75% of cases. Neurological symptoms are present in about 90% of cases, muscle and bone symptoms are seen in around 70% of cases, eye issues are present in 25% of cases, and 10% of people have heart defects. Changes to the scalp and hair such as changes in hair color, hair loss, and hair that is brittle and white or grey can also occur. Less common symptoms include issues with the genital, endocrine (hormone), and dental systems.

Testing for Hypomelanosis of Ito

Hypomelanosis of Ito is typically diagnosed by examining the patient. A special lamp, known as a Wood’s lamp, is used to highlight the patches of lighter skin that are a common symptom of this condition, aiding in confirming the diagnosis.

Any person who has lighter patches of skin (known as hypopigmentation) appearing in a pattern like the ‘lines of Blashko’, should undergo a thorough check-up. This check-up should consider potential issues in the nervous system, bones and muscles, heart, urinary system, or eyes. However, techniques like CT scans or MRIs are necessary only if the person is experiencing neurological symptoms. A simple X-ray of the skeleton will be performed in all cases. If the person is experiencing seizures, an EEG, which is a procedure to record the electrical activity of the brain, will be conducted.

There are specific criteria to diagnose Hypomelanosis of Ito:

The major criteria are:

Non-hereditary skin-lightening in a streak or patch pattern affecting more than two areas of the body, appearing either at birth or in the first few months of life
Having at least one medical issue related to the nervous system or bones and muscles.

The minor criteria are:

Genetic abnormalities
Having at least two birth defects, but not including those related to the nervous system or bones and muscles.

The diagnosis of Hypomelanosis of Ito is established if at least one major or minor criterion is met, or if two minor criteria are met.

Treatment Options for Hypomelanosis of Ito

Hypomelanosis of Ito is a condition that produces certain unique symptoms, and the treatment is aimed at addressing those specific issues. There are no special treatments required for skin spots or discolorations, but if a person is concerned about their appearance due to this condition, they can use cosmetic products or makeup to help disguise them.

Additional support, like special education, might be needed, especially if there are any learning difficulties associated with this condition. Sometimes, the condition can cause seizures, in which case anticonvulsant drugs will be necessary to manage them.

It’s important for patients with hypomelanosis of Ito to have regular check-ups to watch for any complications. Sharing information about this genetic condition within the family is also a key part of managing it, so genetic counseling, which helps in understanding the cause and potential risk to other family members, is an important aspect of the care plan.

These are various skin conditions that could be confused with each other due to their similar symptoms:

Systematized nevus depigmentosus
The fourth stage of incontinentia pigmenti
Piebaldism
Teitz syndrome
Waardenburg disease
Segmental vitiligo

What to expect with Hypomelanosis of Ito

The skin-related symptoms generally indicate a good outcome. However, the overall progression of the condition will depend on how serious the related abnormalities are. Thankfully, cases leading to death are rare.

Possible Complications When Diagnosed with Hypomelanosis of Ito

In some cases, various complications might arise due to the presence of other existing abnormal conditions. One extremely rare complication is the transformation of affected skin into a malignant or cancerous state.

Below is a simplified list of further potential complications, categorized by the body system they affect:

Neurologic symptoms: These can include seizures in 50% to 75% of patients, delayed mental and physical development in 30% to 75% of patients, an abnormally large or small head, autism, problems with coordination and balance, underdevelopment of the brain, malformation of the corpus callosum or the band of nerve fibers joining the two sides of the brain, and symptoms related to mental health disorders.
Musculoskeletal symptoms: These can include one side of the body growing larger than the other, limbs of different sizes, abnormalities in fingers, low muscle tone, curvature of the spine, short stature, and deformity of the rib cage.
Cardiac symptoms: These may include a combination of four heart defects known as tetralogy of Fallot, holes in the wall that separates the chambers of the heart, and a narrowing of the passage from the right ventricle to the pulmonary artery.
Ophthalmologic symptoms: These can include underpigmentation of the retina, narrowing or blockage of the tear duct, misaligned eyes, blurred vision due to irregular shape of the cornea, repetitive uncontrolled eye movements, drooping of the eyelid, wide-set eyes, and clouding of the eye lens.
Genitourinary symptoms: These include having only one kidney, formation of noncancerous cysts in the kidney, underdevelopment of the penis, undescended testicles, and duplication of the tube that carries urine out of the body.
Endocrine symptoms: Early onset of puberty
Oro-dental anomalies: Malformations of the teeth, such as underdevelopment, misshapen teeth, and missing teeth
Vascular anomalies: These include underdevelopment of the large blood vessel that supplies blood to the abdomen, pelvis and legs, and abnormal blood vessels in the brain.

Frequently asked questions

Hypomelanosis of Ito, also known as pigmentary mosaicism, is a disease characterized by light-colored or less pigmented streaks or lines on the skin, following a pattern known as Blaschko's lines. It is a rare condition that affects both the nerves and the skin, and can also have impacts on other systems in the body including the brain and muscles.

In one Italian city, it's estimated that about 1 in every 7540 newborns has this condition. Generally, about 1 in every 82,000 people may have it. In Spain, about 1 in every 8,000 to 10,000 new patients admitted to a children's hospital were diagnosed with HI.

Signs and symptoms of Hypomelanosis of Ito (HI) include: - Light patches on the skin that follow patterns known as the lines of Blashko. - These patches can be on one or both sides of the body and can either be scattered or cover large areas. - The patches generally do not appear on the palms of hands, soles of feet, or inner body cavities. - They can appear anywhere on the body, but are less common on the head. - The light skin patches may only become noticeable a few months after birth or after sun exposure. - Other skin issues may also be present, such as café-au-lait spots, hardening and thickening of the skin (morphea), scaly skin (ichthyosis), blue or bluish-grey skin discolorations (Nevus of Ota and Mongolian blue spots), tumor of the hair follicle (pilomatrixoma), soft skin growths (soft fibroma), and skin irritation (atopic dermatitis). - Neurological symptoms are present in about 90% of cases. - Muscle and bone symptoms are seen in around 70% of cases. - Eye issues are present in 25% of cases. - 10% of people with HI have heart defects. - Changes to the scalp and hair, such as changes in hair color, hair loss, and hair that is brittle and white or grey, can also occur. - Less common symptoms include issues with the genital, endocrine (hormone), and dental systems.

The cause of Hypomelanosis of Ito is currently unknown.

Systematized nevus depigmentosus, the fourth stage of incontinentia pigmenti, piebaldism, Teitz syndrome, Waardenburg disease, segmental vitiligo.

The types of tests needed for Hypomelanosis of Ito include: - Examination using a Wood's lamp to highlight patches of lighter skin - Thorough check-up to consider potential issues in the nervous system, bones and muscles, heart, urinary system, or eyes - X-ray of the skeleton in all cases - EEG (electroencephalogram) if the person is experiencing seizures - CT scans or MRIs if the person is experiencing neurological symptoms

The treatment for Hypomelanosis of Ito is aimed at addressing the specific symptoms associated with the condition. There are no special treatments required for skin spots or discolorations, but cosmetic products or makeup can be used to help disguise them if a person is concerned about their appearance. Additional support, such as special education, may be needed if there are any learning difficulties. In cases where seizures occur, anticonvulsant drugs will be necessary to manage them. Regular check-ups are important to monitor for any complications, and genetic counseling is also an important aspect of the care plan to understand the cause and potential risk to other family members.

There are no specific side effects mentioned when treating Hypomelanosis of Ito. However, the treatment for this condition focuses on addressing specific symptoms and complications that may arise. Some potential complications categorized by body system include: - Neurologic symptoms: seizures, delayed mental and physical development, abnormal head size, coordination and balance problems, underdevelopment of the brain, malformation of the corpus callosum, and symptoms related to mental health disorders. - Musculoskeletal symptoms: asymmetry in body size, limb abnormalities, finger abnormalities, low muscle tone, spinal curvature, short stature, and rib cage deformity. - Cardiac symptoms: tetralogy of Fallot, heart chamber wall defects, and narrowing of the passage from the right ventricle to the pulmonary artery. - Ophthalmologic symptoms: underpigmentation of the retina, tear duct narrowing or blockage, misaligned eyes, blurred vision, uncontrolled eye movements, drooping eyelid, wide-set eyes, and clouding of the eye lens. - Genitourinary symptoms: single kidney, noncancerous kidney cysts, underdevelopment of the penis, undescended testicles, and duplication of the urinary tube. - Endocrine symptoms: early onset of puberty. - Oro-dental anomalies: tooth malformations such as underdevelopment, misshapen teeth, and missing teeth. - Vascular anomalies: underdevelopment of the large abdominal blood vessel and abnormal brain blood vessels.

The prognosis for Hypomelanosis of Ito depends on the severity of the related abnormalities. Generally, the skin-related symptoms indicate a good outcome. However, cases leading to death are rare.

A dermatologist.

Chromosomal Abnormalities Congenital Disorders Genetic Disorders Linear Nevoid Hypopigmentation Lines of Blashko