epidermal nevus

What are Epidermal Nevus?

Epidermal nevi, also known as epidermal naevi, are benign (non-cancerous) patches of skin that result from an overgrowth of cells in the outermost layer of skin. These growths can appear at birth or develop in early childhood.

Characteristics of Epidermal Nevus

• Typically seen at birth or develop in early childhood
• Abnormal, noncancerous (benign) patch of skin caused by an overgrowth of cells in the outermost layer of skin [10]
• Can vary in size and shape
• May be light or dark brown in color
• Can start as a flat area in the shape of a line or as a "skin tag"
• Over time, they grow and become thicker [9]

Types of Epidermal Nevus

Epidermal nevi can take various forms, including:

• Keratinocytic epidermal naevi: These are the most common type and result from an overgrowth of keratinocytes, a type of skin cell.
• Organoid naevi: These are less common and involve an overgrowth of other types of skin cells or structures.

Other Names for Epidermal Nevus

Epidermal nevi are also known as epidermal naevi, systematised epidermal naevi, or Becker nevus (in the case of a specific type).

Prevalence and Distribution

Epidermal nevi affect about 1 in 1,000 people [3]. They can appear anywhere on the body but are most commonly found on the trunk, arms, and legs.

References: [3] - Context reference 8 [9] - Context reference 9 [10] - Context reference 10

Overview of Signs and Symptoms

Epidermal nevi are congenital malformations that can manifest in various ways, depending on the specific type of ENS and associated extra-cutaneous symptoms. The signs and symptoms can vary greatly among individuals and may not necessarily be present in all cases.

Common Signs and Symptoms:

• Skin Lesions: Epidermal nevi are characterized by abnormal growths or lesions on the skin, which can be single or multiple.
• Texture Changes: All epidermal nevi show some changes in texture, which can range from a normal skin tone to a more prominent, wart-like appearance.
• Location: Lesions may be present at birth or develop in early childhood and are usually found on the trunk, limbs, face, or other areas of the body.

Additional Symptoms:

• Irritation or Itchiness: In some cases, epidermal nevi can become irritated or itchy, especially if they are located in areas where clothing or jewelry is rubbing against the skin.
• **Associated Extra-Cutaneous

Diagnostic Tests for Epidermal Nevus

Epidermal nevus can be diagnosed through a combination of clinical evaluation, patient history, and additional tests.

• Clinical Evaluation: A thorough examination by a healthcare provider is usually the first step in diagnosing epidermal nevus. The provider will look for characteristic symptoms such as abnormal skin patches or lesions.
• Skin Biopsy: In some cases, a small sample of affected skin may be taken for microscopic study (biopsy) to confirm the diagnosis and rule out other conditions.
• Genetic Testing: Genetic evaluation plays an important role in diagnosing epidermal nevus syndromes. Specific mutations can provide clues to associated extracutaneous manifestations.

Additional Tests

• Imaging Studies: MRI scans may be used to evaluate intracranial involvement and detect conditions such as cerebral atrophy, dilated ventricles, hemimegalencephaly, pachygyria, or other abnormalities.
• Skeletal Assessment: A full skeletal assessment with imaging by radiology or a second opinion by orthopedics and endocrinology may be necessary in cases of coexistent rickets.

Key Points

• Diagnosis is usually clinical, although dermatoscopy and/or biopsy can be utilized to further examine the lesion in cases where there may be uncertainty.
• Genetic evaluation plays an important role in diagnosing epidermal nevus syndromes.
• Imaging studies such as MRI scans may be used to evaluate intracranial involvement.

References

• [3] An epidermal nevus (plural: nevi) is an abnormal, noncancerous (benign) patch of skin caused by an overgrowth of cells in the outermost layer of skin.
• [8] Diagnosis is usually clinical, although dermatoscopy and/or biopsy can be utilized to further examine the lesion in cases where there may be uncertainty as to the diagnosis.
• [11] When epidermal nevus syndromes are suspected, genetic evaluation plays an important role because the specific mutation may harbor clues to the associated extracutaneous manifestations.
• [9] MRIs can be used to evaluate intracranial involvement. MRIs may show cerebral atrophy, dilated ventricles, hemimegalencephaly, pachygyria, or other abnormalities.
• [10] An astute pediatrician should perform a full skeletal assessment with a referral for imaging by radiology or a second opinion by orthopedics and endocrinology in the case of coexistent rickets.

Treatment Options for Epidermal Nevus

Epidermal nevus can be challenging to treat, but various medications have been found to be effective in managing the condition. Here are some of the treatment options:

• Oral Retinoids: Oral retinoids have an anti-proliferative action on the epidermis and can help prevent recurrence. However, their use must be life-long [1].
• Topical Keratolytics: Topical keratolytics increase the rate of skin shedding and can help reduce the size of the growths [5].
• Vitamin D Analogues: Vitamin D analogues, such as calcipotriol, may be tried in each form of epidermal nevus, particularly inflammatory linear verrucous epidermal nevus [7].
• Combination Therapies: Combination therapies, such as topical 0.1% tretinoin cream and 5% 5-fluorouracil, have been found to be effective in treating linear epidermal nevi [9].

Specific Case Reports

In some cases, specific medications have been used to treat epidermal nevus. For example:

• Fluocinonide Ointment and Tacrolimus 0.1% Ointment: A combination of these two therapeutic agents was found to be effective in resolving lesions [4].
• Topical Ketamine 10% – Amitriptyline 5%: This combination was used to treat pruritus associated with an epidermal nevus, resulting in successful treatment [6].

Prescription Medications

In addition to the above-mentioned medications, other prescription medications may also be effective in treating epidermal nevus. These include:

• Topical Steroids: Useful for reducing inflammation and itching [5].
• Keratolytics: Increase the rate of skin shedding and can help reduce the size of growths [5].

It's essential to consult a dermatologist or healthcare professional to determine the best course of treatment for epidermal nevus. They will be able to provide personalized advice based on individual circumstances.

References:

[1] Oral Retinoids [4] Fluocinonide Ointment and Tacrolimus 0.1% Ointment [5] Prescription Medications: Keratolytics, Topical steroids [6] Topical Ketamine 10% – Amitriptyline 5% [7] Vitamin D Analogues [9] Combination Therapies

Differential Diagnosis of Epidermal Nevus

Epidermal nevus, a benign growth of the skin, can be challenging to diagnose due to its varied presentations and potential overlap with other conditions. Here are some key differential diagnoses to consider:

• Linear and whorled hypermelanosis: This condition presents with linear or whorled pigmentation patterns on the skin, which can be similar to epidermal nevus.
• Nevus sebaceus: Also known as Jadassohn's tumor, this is a benign growth that typically appears on the scalp and can be mistaken for an epidermal nevus.
• Seborrheic keratosis: This common skin condition presents with small, rough patches or bumps on the skin, which can be similar to epidermal nevus in appearance.
• Wart: A viral infection that causes small, rough growths on the skin, warts can be mistaken for epidermal nevi, especially if they are linear or whorled in pattern.
• Psoriasis: This chronic autoimmune condition presents with red, scaly patches on the skin, which can be similar to epidermal nevus in appearance.
• Acanthosis nigricans: A skin condition characterized by dark, velvety patches on the skin, acanthosis nigricans can be mistaken for epidermal nevus, especially if it presents with linear or whorled patterns.
• Lichen striatus: A rare skin condition that presents with linear or whorled lesions on the skin, lichen striatus can be similar to epidermal nevus in appearance.
• Incontinentia pigmenti: A genetic disorder that affects the skin and other organs, incontinentia pigmenti can present with linear or whorled pigmentation patterns on the skin, which can be mistaken for epidermal nevus.
• Hypomelanosis of Ito: A rare genetic disorder that presents with hypopigmented patches on the skin, hypomelanosis of Ito can be similar to epidermal nevus in appearance.
• Inflammatory linear verrucous epidermal nevus (ILVEN): This is a subtype of epidermal nevus that presents with linear or whorled lesions on the skin, which can be mistaken for other conditions.

Key Takeaways

When diagnosing epidermal nevus, it's essential to consider these differential diagnoses and rule out other conditions that may present similarly. A thorough medical history, physical examination, and diagnostic tests (such as biopsy) are crucial in making an accurate diagnosis.

References:

• Weedon D. Skin Pathology (2nd edition, 2002).
• Masood Q, Narayan D. Squamous cell carcinoma in a linear epidermal nevus. J Plast Reconstr Aesthet Surg 2009; 62:693.
• Turk BG, Ertam I, Urkmez A, et al. Development of squamous cell carcinoma on an inflammatory linear verrucous epidermal nevus in the genital area. Int J Dermatol 2015; 54(12):e631-e634.