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Verrucous nevus

 
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Last reviewed: 16.04.2020
 
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Epidermal nevus verrucosus (nevus verrucosus) is a benign pigmented protrusion on the surface of the skin that resembles a wart (in Latin, a wart is a verruca), which is why it is also called a warty mole. Verrucous epidermal nevus (VEN) is a skin disease that usually occurs at birth and is often resistant to treatment. [1]

Epidemiology

Verrucous nevus, according to some reports, is present in 0.1% of the population; they account for about 6% of all epidermal nevi. [2]

Causes of the verrucous nevus

Despite the histological differences between different  types of moles on the body  - limited areas of abnormal accumulation (hypertrophy) of non-cancerous skin cells - the reasons for their appearance are identical.

Neurogenesis, that is, the development of verrucous, as well as other melanocytic and keratinocytic  nevi , is a complex process. Today, it is believed that congenital moles as a skin defect sporadically appear due to errors in the migration of melanocytes (cells that produce skin pigment) from the neural crest into the embryonic period.

More information in the material -  Causes of the appearance of moles .

Risk factors

The main risk factors for the development of congenital nevus are considered to be heredity, pregnancy pathologies and teratogenic effects on the fetus, which negatively affect the entire process of embryonic development.

The risk of the appearance of verrucous moles increases the effect of high doses of ultraviolet radiation and especially sunburn, in which the function of skin melanocytes is activated and the synthesis of melanin is enhanced.

Pathogenesis

Nevus cells - nevocytes - are a type of melanocytes, but they are larger than typical pigment cells - with larger cytoplasm and large granules, do not have dendrites, deposit melanin and are localized by clusters at the border between the dermis and epidermis and in the dermis.

It is now known that in 40% of cases, the pathogenesis of epidermal nevus - including verrucous - is associated with genetic mosaicism, splicing, or mutations in the FGFR3 and PIK3CA genes. The FGFR3 gene encodes the formation of a protein - receptor of fibroblast growth factor type 3 (FGFR-3), which plays an important role in cell processes of embryogenesis, as well as in the proliferation (division) of cells, their differentiation and angiogenesis (formation of blood vessels). [3]

The PIK3CA gene encodes the synthesis of p110 alpha (p110α) protein, a subunit of the enzyme phosphatidylinositol-3-kinase, which provides the transmission of intracellular chemical signals that regulate cell growth, division, migration and apoptosis. [4]

Moreover, it was found that mutations associated with nevus affect only mole cells and are not detected in normal skin cells.

Symptoms of the verrucous nevus

Usually, verrucous nevus is already present in newborns or begins to manifest in infancy, slowly increasing in the future. For adults, the appearance of this type of nevus is uncharacteristic.

Symptoms of such a nevus are hyperpigmented papules of yellowish-brown color, merging into plaques of various sizes and shapes with a tuberous or granular surface. Formations can be single, but more often they are multiple. Their specificity is a linear or curved-discontinuous configuration - along the so-called Blashko lines (directions of migration of embryonic cells from the neural crest). [5]

Verrucous nevi can be one-sided, bilateral, or located on any part of the skin, for example, along the entire limb, on the chest, abdomen, or back.

Complications and consequences

Verrucous epidermal nevuses are often immune to treatment and have a high relapse rate. [6]Verrucous nevus is not prone to malignant degeneration (that is, it is classified as melanomoneous). The negative consequences and complications of this type of epidermal nevi can be the result of traumatic exposure and infection of the damaged skin area. See also:  Dangerous and non-dangerous changes in moles Why does a mole itch and what to do?

Diagnostics of the verrucous nevus

In addition to a visual examination of the patient's skin, the diagnosis includes:

See also publication -  Mole Diagnosis

Differential diagnosis

Differential diagnosis should distinguish between verrucous nevus and congenital linear porokeratosis, Solomon’s syndrome (Schimmelpenning-Feuerstein-Mims syndrome), actinic keratosis, linear lichen (lichen), ulcerative stage of pigment incontinence, Siemens ichthyosis bullosa. [7]

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Treatment of the verrucous nevus

As in the case of other moles, the treatment of a warty nevus consists in its removal, that is, surgical treatment, in more detail,  Surgical removal of moles . However, surgical removal may not be possible when the skin lesion is very extensive, and this can lead to scarring. Many other treatments have been reported, including topical treatments, cryotherapy,  [8]laser treatments,  [9]photodynamic therapy, and chemical peels with different clinical outcomes. [10], [11]

See also:  Removing moles: an overview of the main methods

However, according to clinical practice, after the removal of epidermal nevi, their relapses are possible.

Forecast

In the presence of such a nevus, the prognosis can be considered favorable, since at a certain stage the formation ceases to increase, and its degeneration into melanoma is practically excluded.

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