Types of pigmented nevi, danger of degeneration, removal methods, prevention. Becker's nevus and congenital giant nevus

Giant pigmented nevus

Synonyms: congenital pigmented nevus, congenital melanocytic nevus, congenital noncellular nevus, giant hairy pigmented nevus.

In general, congenital noncellular nevi are initially benign pigmented tumors consisting of nevus cells. Their occurrence is the result of a violation of the differentiation of melanoblasts, which occurs, according to scientists, between the 10th and 25th weeks of intrauterine development. These neoplasms are either detected at birth or appear during the first months of life. The sizes of nevi vary from tiny, barely noticeable, to gigantic. Their main feature is that they are all potential precursors of melanoma. But the frequency of transition of congenital nevi to melanoma is directly dependent on their size.

Giant pigmented nevus is a special case of congenital noncellular nevus.

Congenital nevi can be represented by macular, nodular, papular or warty elements. The shape can be regular or irregular, the boundaries can be clear or blurred. Hair may grow on the surface of the nevus. The consistency resembles ordinary skin: soft, pliable, sometimes elastic. A dense consistency is rarely observed as an exception. The sizes are very different: small (less than 1.5 cm), medium (5-10 cm), large (10-20 cm) and giant (more than 20 cm). Favorite localization is the lower torso, upper back, chest, proximal limbs. A giant pigmented nevus often occupies a significant part of the skin surface - entire anatomical areas.

As the giant nevus grows, its pigmentation becomes heterogeneous and the surface becomes warty, sometimes with the presence of nodes. Hair growth is observed in 95% of cases and is especially often observed in late childhood, when the giant nevus stops thickening and becomes paler.

Microscopy. According to the histological structure, congenital nevi are most often classified as epidermal, dermal or mixed, less often - blue, spindle cell and other types. Unlike acquired melanocytic nevi, congenital pigmented nevi are characterized by an increased content of melanocytes in the basal layer of the epidermis and their absence in the papillary layer of the dermis, while aggregates of dermal nevus cells are found in the lower layers of the dermis. The presence of nevus cells in the lower third of the reticular layer of the dermis or in the subcutaneous fatty tissue clearly indicates that the nevus under study is congenital. The lifetime risk of developing melanoma from small congenital nevi is 1-5%. Giant nevi have a higher malignant potential, and the probability of their transformation into melanoma during life is 6-20, and according to some data - 40%.

With a giant pigmented nevus, the risk of developing melanoma is high even in the first years of life. Of course, the approach to such patients should be individual, taking into account the size, location of the nevus, the patient’s age, the possible relative decrease in the tumor as the body grows, as well as the degree of disability as a result of surgical intervention. Giant nevi should be removed as early as possible. Treatment of large and giant nevi is carried out in specialized oncological treatment institutions and clinics, the addresses of which are not difficult to find in reference books. The method of choice here is early extensive excision of the tumor followed by plastic surgery with local tissues, free skin transplantation, combined skin grafting, autotransplantation of a complex of tissues at vascular anastomoses, replacement of a skin defect with cultures of epidermal autocells artificially grown on synthetic dermal substitutes, etc. After removal of a congenital noncellular nevus, the patient must be under lifelong dispensary observation.

Additionally

This is a congenital benign skin tumor, which is a large pigment spot (more than 20 cm), sometimes occupying a significant part of the limb or torso. Due to its characteristic appearance, diagnosing such a nevus is not difficult. A giant pigmented nevus is a melanoma-dangerous nevus, so it is advisable to remove it. However, due to the large size, this is not always possible. Patients with an unremoved nevus should undergo regular examinations by a dermato-oncologist for timely diagnosis of the onset of its malignant transformation.

General information

The appearance of a giant pigmented nevus is caused by a disruption in the process of melanoblast differentiation that occurs in the fetus in the period from the 10th to the 25th week of its intrauterine development. The frequency of birth of a child with such a nevus is 1 in 500 thousand newborns. However, according to some data, giant nevus occurs in 1-2% of the world's population. The disease can be combined with other congenital anomalies, for example, hydrocephalus, Recklinghausen neurofibromatosis, epilepsy, primary melanoma of the pia mater of the brain.

Symptoms of a giant pigmented nevus

Due to its enormous size, a giant pigmented nevus often occupies entire anatomical areas. It can be located on the torso, limbs, neck or head. With its symmetrical arrangement, a pattern resembling a vest appears on the body, and a collar appears on the neck. It is possible to combine a giant nevus with multiple small nevi, which are usually located at some distance from it.

The surface of the giant nevus is uneven, the color can vary from gray and brown to black. Over time, the skin of the affected area thickens and pigmentation increases. In this case, different areas of the nevus may have different colors. The surface of the nevus becomes heterogeneous, bumpy and warty. In most cases, hair appears on certain areas of the nevus. Since the giant pigmented nevus grows slowly, as the child grows, a relative decrease in the size of the nevus is observed. At the end of adolescence, there is a decrease in the pigmentation of the nevus and a cessation of its thickening.

Like other congenital nevi, a giant pigmented nevus remains on the skin of its owner throughout his life. Such nevi persist even into very old age, when a gradual disappearance of all acquired nevi occurs.

Complications of giant pigmented nevus

The main complication of a giant nevus is its malignancy and transformation into melanoma. This process can be triggered by various acute or repeatedly traumatic effects on the nevus: mechanical, radiation (including sun rays), chemical.

The transition from a giant pigmented nevus to melanoma can occur at any age. According to various sources, this occurs in 2-13% of cases of the disease. When a nevus transforms into melanoma, its accelerated growth, changes in outline and color, bleeding, and the appearance of erosions and crusts on the surface are noted.

Diagnosis of giant pigmented nevus

The diagnosis of a giant pigmented nevus is made possible by its characteristic appearance and the fact that the nevus has been present on the skin since birth. Additional studies are needed to timely detect the transformation of nevus into melanoma. Most often, dermatoscopy and siascopic examination are used for this purpose, allowing one to study the structure and edges of the nevus under 10-30x magnification. Using dermatoscopy to plan the operation, the boundaries of the nevus are accurately determined.

The histological picture of a giant pigmented nevus, like other congenital pigmented nevi, is characterized by the absence of melanocytes in the papillary layer of the dermis and an increase in their content in the basal layer of the epidermis. Nevus cells are detected in the lower layers of the dermis, subcutaneous fatty tissue and skin appendages: ducts of sweat and sebaceous glands, hair follicles. With a giant pigmented nevus, nevus cells also penetrate into the muscles, bones and meninges.

Treatment of giant pigmented nevus

Despite the large size of the nevus and the infant age of the patients, the best way to treat it is removal. Such treatment tactics are associated with a high probability of malignancy of a giant nevus, which can occur already in the first year of life. The decision about surgery is made individually, taking into account the location and size of the nevus, the age and health status of the patient, the degree of possible disability as a result of the operation, etc. If the operation is postponed, the patient needs constant monitoring by an oncologist with examinations at least once a quarter.

Surgical treatment of giant pigmented nevus is carried out jointly by dermato-oncologists and plastic surgeons. It consists of complete excision of the nevus, capturing 0.5 cm of healthy skin located on the border with it. If the size and location of the nevus do not allow it to be removed immediately, stage-by-stage excision is performed. The material removed during the operation must undergo histological examination. Large skin defects resulting from the operation require closure by skin grafting. Plastic surgery can be performed using free skin grafting or autodermoplasty with transplantation of one’s own skin flaps at vascular anastomoses. To plastically close the defect, the technology of artificially growing cultures of one’s own epidermal cells on synthetic analogues of the dermis is also used.

So-called nevi, or moles in other words, are present on the skin of the human body in almost everyone. Such birthmarks often do not pose any danger to human health and life, not counting those types that by their nature can degenerate into malignant neoplasms - melanomas.

Important! It is necessary to keep every mole on your own body under control, protecting yourself from possible danger.

Nevi or benign tumors of nevoid origin, birthmarks, moles are a kind of developmental defect with its characteristic manifestation on the skin, sometimes on the mucous membrane, as well as on the connective membrane of the eyeball and on its vascular part in the form of spots, skin phenomena filled with nevoid cells .

The so-called cellular potential of nevi tends to arise, starting from intrauterine development. It appears from the neural crest - a certain collection of cells that serves as the basis for the development of various anatomical formations. Usually found in the form of nerve ganglia, meninges, and pigment spots (melonocytes) of the skin.

Melanoblasts, which are the precursors of melonocytes, move to the deeper layers of the epidermis, and those that do not reach them settle in the dermis (located under the epidermis).

According to available statistics, nevi occur in 75% of Caucasians. An adult often has more than 20 nevi, but this is not the limit. In childhood, a nevus may not manifest itself, but at the time of puberty, under the influence of solar activity, as well as during pregnancy, the formations remind of their presence.

Throughout life, the described education is represented by several phases of its development:

Initially, in its development, the nevus is intraepthelial;
then the skin phenomena degenerate into a borderline form;
at the age of 30 it enters the phase of the intradermal form.

In old age, the nevus begins its reverse development: the formation cells “go” into the layers of the dermis and change. This system is due to aspects of simplification of the organization and function of melanocytes.

Causes

Nevi are represented by overgrown skin cells of a certain kind in the form of growths or seals located on the skin. The darker color of nevi is given by melanin, produced by melanocytes in response to ultraviolet radiation. But this does not mean that the existing formation must necessarily consist of melanocytes. The structure of nevi may also contain pigment produced by these cells.

The formation of nevi is caused by uncontrolled cell division. At a certain point in development, the number of cells becomes excessive, which directly leads to the appearance of the described skin phenomena. Compared to cancer cells, the cellular potential of nevi does not tend to develop rapidly. The majority of moles and all kinds of spots are innate, so to speak, naturally growing along with the body.

Well, after the growth of the body begins at the age of 30, the growth of moles also decreases and stops.

The appearance of nevi itself is due to certain factors:

limited developmental defects;
heredity;
exposure to ultraviolet radiation;
injuries;
hormonal factors;
due to the influence of viruses and due to bacterial infection.

Causes of limited developmental defects

This reason, first of all, concerns congenital moles, which manifest themselves when the division of epidermal cells is disrupted in the last stages of fetal development. The described skin phenomena are so small that they are sometimes simply not visible. The formations become visible only by the 4th year of a child’s life, due to a significant increase in his skin. About 60% of all described skin phenomena on the human body can be attributed to the origin of this kind.

Heredity

Many people know the fact that the described skin phenomena are transmitted through inheritance. This was noticed many centuries ago, before the advent of DNA testing itself.

In fact, inheritance factors work as follows - existing skin phenomena are encrypted by a chain of genes at the molecular DNA level. Together with the genetic basis, this chain with a chromosome is inherited by children, having received it, so to speak, as an inheritance from their ancestors.

After the birth of a child, his body begins its development according to a certain algorithm, which was laid down at the level of genetic material. Any described skin phenomena originate in the process of decoding, as well as during the interpretation of genes as the body continues to grow and develop. Such neoplasms are often benign.

Note! This possibility of transmitting certain birthmarks or moles is equal to 50%, but only on the condition that the existing parental formations are also a hereditary factor.

Nevi that appear during life itself are not transmitted through inheritance, since they are not predetermined in the gene sequence.

Causes of ultraviolet exposure

Ultraviolet light stimulates the activity of melanocytes in the skin. In order for pigment production to become even more intense, the body begins to produce an increased amount of melanotropic hormone. Therefore, with constant exposure to ultraviolet radiation on the skin, the number of melanocytes only increases. That is, instead of tanning, which performs a protective function of protecting the skin from radiation, a certain pathology occurs, consisting of rapid cell growth. The highest level of sensitivity to ultraviolet radiation occurs in women who have crossed their 30th birthday.

Injuries

A variety of mechanical injuries to the skin, such as an insect bite, a scratch, or some other wound, according to certain experts, play an important role in the development of the described skin phenomena. This occurs during inflammatory processes, along with the production of a large number of biologically active substances that stimulate cell growth. The described factor in the appearance of nevi is quite rare.

Hormonal reasons

During long-term observation, researchers noted the involvement of hormones in the formation of moles and age spots. This often happened at the time of puberty, during pregnancy, as well as with various endocrine ailments, along with physiological or pathological hormonal changes in the body. Moles, quite large in size, born due to hormonal surges, have virtually no tendency to become malignant.

Viral and bacterial infection

This reason was confirmed after a number of cases that occurred in various countries, where nevi were born as a result of viral infection, along with the inflammatory nature of a particular disease.

Summing up and relying on some points and patterns of the appearance of skin phenomena, we can say that the more often a person develops nevi throughout his life, the greater the risk of their malignant transformation.

Types of nevi

Nevi are divided into two fairly large groups, based on the mechanism of their appearance. Nevi can be:

congenital neoplasms that are practically not susceptible to transformation into melanoma;
acquired formations that appear on human skin throughout their life, under the influence of various factors.

Congenital and acquired formations may have some similarity to each other in their existing structure.

Histological classification of nevi evaluates the most important features of a particular type of tumor, which makes it possible to quite effectively predict the course of the existing disease. Of the existing 50 types of moles, 10 are the most common. They are caused by two groups, which include: melanoma-hazardous and melanoma-non-hazardous nevi. The former do not have a tendency to become malignant, while the latter have every reason for this.

The following types of melanoma-dangerous nevi include:

intradermal pigmented nevus;
papillomatous nevus;
Mongolian spot;
fibroepithelial nevus.

Type - intradermal pigmented nevus

This type of mole most often corresponds to adolescence. Usually they begin their formation under the skin, in the dermis. These moles are small in size, only a few millimeters. As the body grows and develops, moles also begin to grow and change color until old age. Compared to other nevi, these skin phenomena in old age do not tend to develop sharply. Only 20%, under the influence of certain moments, can degenerate and become malignant.

The most commonly described intradermal skin phenomena are:

on the cervical regions;
in the skin folds of the extremities (in the groin or armpits);
under a woman's breast;
not often on the skin of the body, as well as on the arms and legs.

Type - papillomatous nevus

This type of nevus is due to its unpleasant appearance. Such moles rise excessively above the skin; they look like a kind of growth, differing in color and texture. They may be brown or pinkish in color and have a grainy consistency. The mole is quite soft and painful to the touch. Trouble is caused only in the form of a cosmetic defect.

Such moles are most often located on the head under the hair, but can also be found on the body. Has a certain hair follicle. They grow throughout a person’s life, but slowly. They are rarely reborn. But due to some similarity with certain types of malignant melanomas, in the presence of such a nevus, a person is recommended to undergo a biopsy.

Variety - halonevus

Galonevus has another name - Setton's nevus. This is an acquired type, a nevus that appears in people with a weakened immune system, due to hormonal disorders, or occurs as a result of any autoimmune diseases.

This is a large, oval mole protruding above the epidermis. The size of the described skin phenomenon is several millimeters, and the width of the depigmented area is 2 mm, but sometimes it reaches 2 cm. Most often, such skin phenomena are present on the skin of the human torso, as well as on the arms and legs. There are multiple formations of the described phenomena on the human body.

If there are a large number of diagnostic procedures, removal of such moles is not recommended. Such skin phenomena do not have a tendency to become malignant.

Variety - Mongolian spot

This type of nevus manifests itself as a birthmark in newly born children, less often in adults. The Mongolian spot is the result of a hormonal pigment disorder. Nevus owes its name to the Mongols. In newborn babies, it manifests itself in 90% of cases. Over time, these nevi may disappear without a trace.

Birthmarks usually appear in the sacral area or on the buttocks, and reach up to 15 centimeters in diameter. It rarely degenerates into melanoma and does not require special therapy.

Type - fibroepithelial nevus

The most common type of nevus. Moles of the described type can be either congenital or acquired. The peak of development is the moments of hormonal changes. They can also show their growth in old age. The mole is often large and localized throughout the body. The shade of the described moles, which are soft to the touch, is reddish or pinkish.

Malignancy occurs rarely and is easily removed. Without medical intervention, they do not go away on their own.

Melanoma-dangerous nevi include the following types:

blue nevus;
borderline pigmented nevus;
giant pigmented nevus;
nevus of Ota;
dysplastic nevus.

Variety - blue nevus

Such a nevus can be marked by a precancerous condition, although it is classified as a benign neoplasm. Nevus can manifest itself throughout life; it is represented by an accumulation of melancites in the skin. This neoplasm is caused by a single variant of its manifestation.

Blue nevus cells produce melanin with great activity. Therefore, the shades of such neoplasms can vary, from bluish to blue-black. Such a mole most often rises above the epidermis, has smooth edges and regular shapes. The described skin phenomena do not have a tendency to malignancy. But there is some traumatism, and therefore preventive examinations are recommended for patients with such moles.

Type: borderline pigmented nevus

This type of mole is classified as a congenital neoplasm that manifests itself already in the first stages of life. Without the influence of any external factors, the nevus grows along with the human body. The described nevus reaches sizes ranging from 0.8 to 1.3 mm. Although with good growth it can reach several centimeters in size.

Due to the large amount of melanin present in its composition, the skin phenomenon described is brown, brown or even black. Such skin formations are found on the feet and palms. They can be caused by malignant properties, especially manifested after injury or sunburn.

A variety - giant pigmented nevus;

This nevus is congenital, increases in parallel with a person’s growth and reaches enormous sizes of up to 50 cm in comparison with other described skin phenomena. This nevus rises above the epidermis and has a grayish or brownish color. Such birthmarks are caused by cracks, grooves and warts. Malignization (cells of healthy tissues of the body acquire the properties of a malignant tumor) occurs in 10% of cases, most often due to possible trauma. A surgical solution to the problem is recommended.

Variety - nevus of Ota

In the development of this skin phenomenon, the nervous factor plays a huge role, so to speak. The nevus is located only on the face; the spot itself consists of a large amount of melanin. The color of the neoplasm is black-blue and is localized both on the skin and on the human mucosa. Having a genetic orientation, nevus occurs exclusively in Asian peoples. Malignant transformation practically does not occur.

Type - dysplastic nevus

This skin phenomenon is 50% congenital. There have been cases where similar nevi were detected in several family members at once. The described type of skin phenomena can be no more than 0.5 centimeters in diameter, with multiple manifestations on the surface of the human body. They are localized almost everywhere and have a dark brown color. Such formations are caused by a smooth and flat surface. Without timely removal, they transform into malignant melanoma (in 90% of cases).

Symptoms

In appearance, nevi are quite different from each other. Some are practically invisible on the human body, while others are painted black and have impressive sizes. Nevi are flat in shape, while others rise above the surface of the epidermis. Some moles are caused by hair follicles, while other neoplasms do not show hair growth.

Nevi are localized everywhere and can be found in the most unexpected places on the body, even on the mucous membrane and the eyeball.

Diagnostics

You can identify the danger and the actual nature of the described skin phenomena:

using fluorescent microscopy - using a special device called a dermatoscope. This method, by transilluminating the skin, can reveal the etiology of cells, their location and formation;
the use of computed tomography, which makes it possible to determine not only the deep dimensions of moles, but also their structure;
histology - determination of tumor markers through laboratory tests.

Important! Sometimes it is vitally important to promptly recognize the malignancy of a skin lesion and be able to distinguish it from a malignant tumor.

Treatment

Today, in addition to cosmetic solutions to aesthetic problems associated with moles, the following methods of surgical intervention are used:

the use of resection is to rid a person of a nevus by surgical excision with a scalpel. The disadvantage of this method is that the process is painful; as a result of the operation, scars remain on the human body;
the use of targeted irradiation of a particular nevus with small doses of radiation;
the use of electrocoagulation - removal of the nevus with further sealing of the vessels;
the use of laser correction - nevi are removed quickly, without pain and without any consequences in the form of scars;
cryotherapy – cauterization using dry ice or liquid nitrogen.

Prevention

In order to prevent the transformation of nevi into malignant neoplasms - melanoma (the mortality rate of which reaches 50%), it is necessary:

prevent exposure of the sun's rays to human skin, even in gloomy weather;
try not to swim during solar activity, and in winter do not stay outside for a long time. Since snow and water are ultraviolet reflectors;
use sunscreen cosmetics;
tanning in a solarium must be completely avoided;
conduct constant monitoring of existing moles.

And in conclusion, in order to promptly prevent the process of possible transformation of moles into melanomas, it is necessary to constantly examine your skin for existing nevi. And if the latter cause any concern, then you need to urgently contact a specialist for examination and further examination through laboratory tests.

Video on the topic

Types of moles - acquired and congenital. Classification of nevi according to their size and shape, where regularly convex, symmetrical moles are the norm. Does the defining color of a mole pose any danger? Features of vascular and non-vascular moles? The percentage of malignancy of a particular type of mole? What is an internal mole? A qualified dermatologist will answer these and other questions.

Publication date: 2014-08-24

Pigmented nevus (melanocytic nevus) is a limited, raised above the skin surface, usually a solitary benign pigmented tumor. Such spots are also called moles, but should not be confused with. They usually appear in children during the first days or years after birth. Over the course of life, the quantity, shape and quality of such formations changes. So, in infants and infants, only 10% have moles.

At 15-25 years of age, the maximum growth of moles on the body is observed. The decrease in the number of moles begins after 30, and by old age their occurrence stops altogether. Based on this, the conclusion suggests itself - the formation of moles on the human body corresponds to the activity of its hormonal levels. No treatment is required for nevi unless they have developed into melanoma.

From a histological point of view, moles have the following classification:

Borderline pigmented nevus is a formation whose melanocytic cells are located in the basal epidermal layer;
Intradermal - the location of melanocytic cells is located in the deep dermal layers;
Mixed - has similar symptoms as intradermal and borderline formations.

Depending on the size, they also have a certain classification:

If the size of the mole is 0.5-1.5 cm, it is a small nevus;
1.5-10 cm - secondary education;
The size of large moles is more than 10 cm;
A giant pigmented nevus is a formation that covers a certain area of the body with its area measuring more than 20 cm.

The larger the size of the nevus, the more likely it is to become malignant (malignant). Thus, neoplasms larger than 2 cm risk developing into melanoma in 5-20% of cases. There are also multiple pigmented tumors, which are a large lesion consisting of small moles.

Since pigmented neoplasms are congenital, the reasons for their appearance lie in the processes of melanoblastic development, or more precisely, due to disruption of these processes. They occur during pregnancy 2.5-6 months.

In rare cases, the causes of the appearance of a pigmented nevus are a negative consequence of skin pathology, genitourinary infection, etc. Sometimes the cause of formation in a child is the harmful effects of poisons, toxins, radiation on the mother’s body during pregnancy.

Symptoms

Pigmented nevus can be brown, black and even blue in color with a smooth, lumpy, papillomatous, folded, lobulated texture or skin pattern on the surface. They appear as warty, spotted, nodular or papular elements. Sometimes dark hair grows on the surface of the tumor.

Immediately after birth, small and medium-sized neoplasms in children are usually pale and therefore invisible. As the child grows, they gradually darken and become noticeable. Of all skin formations, only 5% do not have hair on the surface.

Neoplasms can be of different types, as well as different sizes. For example, a border nevus, judging by the photo, has a clear border and has a hairless, dry and smooth surface. Its color can range from dark to light brown. It is no more than a centimeter in size and can appear anywhere, but the genitals, palms, and soles of the feet are considered preferable.

The intradermal type is a dome-shaped papule that rises above the skin level and has a warty-lumpy surface. Most often it chooses a place in the neck or head, like or. It can separate from the skin surface with age, communicating with it by a thin stalk. Over time, it can develop into a papillomatous formation, in the folds of which bacteria that cause infections develop.

A giant pigmented nevus, as confirmed by various photos, most often affects the face, neck, limbs and body. It is characterized by rapid growth and huge (more than 20 cm) sizes. Its surface is usually uneven, warty, riddled with cracks, and covered with a large amount of hair. Most often, the color of such birthmarks has gray or black shades. The risk of degeneration in such cases into melanoma exceeds 45% of cases.

Alarming symptoms

In general, such diseases do not require specific treatment or removal, with the exception of their degeneration into malignant tumors. Characteristic symptoms will help to recognize it; a sign of malignancy is considered to be a sharp growth of the tumor both in width and height. Changes in color and structure are also considered dangerous symptoms.

Symptoms associated with bleeding and ulceration of pigmented birthmarks may also indicate tumor degeneration. If a scattering of new pinpoint formations appears near a mole or a pigmented area has formed around it, you should immediately contact a specialist.

Treatment

Typically, treatment or removal of a pigmented nevus is prescribed for pain, discomfort, or persistent trauma to the mole. If it does not cause any trouble, then it is not recommended to touch it. If it is necessary to remove the formation for preventive purposes, it is better to do it before puberty (in childhood).

Treatment of various types of birthmarks is selected individually, in accordance with the type, type and size of the nevus, the characteristics of the body of its owner, and only by a dermato-oncologist. Most often, treatment involves complete removal.

Removal of a pigmented nevus can be done by laser or surgery. Both methods are widely used and have minimal risk of subsequent degeneration. Laser removal leaves no traces, surgical excision is used on large formations and leaves scars.

Nevi are peculiar formations on the skin, sometimes appearing on the mucous membranes and conjunctiva. Consist of nevus cells. People call them moles and pigment spots.

Definition and basic properties

Nevus cells appear during fetal development from the neural crest. The latter is represented by nerve ganglia, meninges, melanocytes, and adrenal cells.

Under the influence of various factors, nevocytes containing large amounts of melanin are formed. The cells synthesize pigment, which gives color to the skin area. The intensity of formation depends on its quantity.

The ICD-10 code for pigmented nevus depends on the type of formation:

D22 – melanoform,
Q82.5 – congenital non-tumor,
I78.1 – non-tumor.

According to statistics, 75% of Caucasians have moles and formations. On the body of any adult, their number on average reaches 20, but some have five times more.

In childhood, nevi often remain invisible; only in adolescence, due to a hormonal surge and under the influence of sunlight, do they begin to make themselves felt. Sometimes new ones appear during pregnancy.

A nevus goes through several stages in its development:

intraepithelial,
intradermal.

Interestingly, older people often experience regression when nevus cells move into the dermis and are replaced by connective tissue.

Classification of nevi

An international classification has been developed, which distinguishes several large groups. Each of them has subspecies:

epidermal-melanocytic,
dermal melanocytic,
melanocytic,
mixed and others.

Epidermal-melanocytic

This type is the most common and is present in almost all adults. It is characterized by a round or oval shape and clear edges. The color ranges from reddish to dark brown.

Photo of epidermal nevus of the skin

The type is divided into:

border,
intradermal,
epidermal,
difficult,
spotted,
formations of balloon-shaped cells,
fibroepithelial,
intracellular,
recurrent,
warty,

Dermal-melanocytic

This type arises from the melanocytes of the dermis. Single formations are rare, so more often we are talking about a multiple nature.

Divided into:

(simple and cellular),
nevus of Ota and Ito,
and Mishera,
combined,
deeply penetrating.

These species can have different colors; some species are distinguished by their large size. They may appear on mucous membranes.

Melanocytic

This variety is one of the most dangerous. It is diagnosed late and is a prerequisite for the development of melanoma. Congenital formations are called verrucous or giant nevi.

The elements themselves can be:

papillomatous,
papular,
nodal.

The most alarming is Clark's nevus, which is a common precursor to melanoma. Appears before the onset of puberty. New formations can appear until old age.

Mixed and other types

Mixed is a transitional form of intradermal and intraepidermal formation, which often has a spherical shape with a dense consistency.

This type includes:

vascular or anemic (capillary hemangioma, flaming nevus, senile hemangioma, etc.),
Becker's nevus,
papillomatous.

This photo shows what a Becker nevus looks like

There is also White spongy nevus of Cannon, affecting the oral mucosa, is a congenital disease and progresses until puberty.

Dangerous and non-hazardous species

There is one more reason on which all moles are divided. This is an opportunity for it to develop into skin cancer. Such types are also melanoma-safe.

The first type includes:

pigment borderline,
giant congenital,
blue,
Reed's nevus,
Spitz nevus,
dysplastic.

The photo shows Reed's nevus

Melanomas-safe include non-neoplasmic formations: intradermal pigment, fibroepithelial, verrucous, Mongolian spot nevus, Setton's nevus.

There are also formations that resemble nevi in appearance. This is a histiocytoma, granuloma.

Varieties in children

These types of nevi are congenital or appear in the first months of a newborn's life. They are often localized on the child’s head, face, neck, back, lip, etc.

Among the most common are:

vascular,
pigment,
pigmentless,
comedoform,
fibromatous,
adenomatous,
angiomatoses,
hyperkeratotic and others.

Causes

Nevi appear due to the influence of external and internal factors.

The cause of congenital formations is changes in embryonic development. It consists in disrupting the migration of cells that enter the skin from the neuroectodermal tube. But even this type does not always appear in a newborn. Parents often notice it in the first years of life.

The acquired species are not distinguished by their static nature. They can change size, color, shape, so constant monitoring is necessary. Often the cause is endocrine changes, as well as skin infections.

All factors influencing the formation of moles are divided into large groups:

Local developmental defects that appear due to impaired cell division in the late periods of fetal development.
Hereditary factors, when formations are encoded by a chain of genes in a DNA molecule.
Ultraviolet radiation leads to stimulation of melanocytes.
Injuries, including insect bites, scrapes and wounds,
Hormonal factors, especially in adolescents and patients with endocrine diseases.
Viruses and bacteria that can affect the skin, as well as injury.

Most moles appear in people who like to spend time in a solarium or vacation in equatorial countries. Factors at work also influence their education.

Chemical industry specialists and workers interacting with carcinogenic substances need to take special care of the skin and newly emerging formations.

Clinical symptoms

Nevi are made up of various cells that are part of the skin. Therefore, they may have different clinical manifestations.

For example, pigmented skin nevi are light brown, red, blue or black. The degree of severity depends on the concentration of melanocytes. Such species evolve and change in size. They can be a few millimeters or hundreds of square centimeters.

The intradermal type has clear boundaries and a soft consistency. Sometimes it has a warty shape or loses its pigmentation. This type appears between the ages of 10 and 30 and never regresses.

Photo of intradermal pigmented nevus

Depending on the type of formation, localization occurs in different areas. Epidermal ones appear more often where there are many sebaceous glands, that is, on the scalp or on the face.

Nevus of Ota is most often located on the upper jaw or cheeks. Often spreads to the sclera and oral mucosa.

Borderline nevi appear on the palms, torso, and soles. Sometimes found on the external genitalia. The change in color and size occurs slowly.

Thus, the following are important when differentiating a nevus:

location,
features of borders,
the presence of hairs growing from the formation,
shade,
age of appearance,
the presence of progress and modifications,
number of moles and others.

Complications of pigment formations

The main complication is the possibility of transformation of a mole into a malignant tumor. Not all formations are prone to such changes; special attention is paid to melanoma-hazardous formations.

Sometimes, under the influence of external factors, even seemingly harmless moles can cause harm. Especially after injury or attempted self-removal.

Signs of degeneration:

rapid increase in size,
the appearance of pain or itching,
color change,
transformation of the surface layer,
loss of clear boundaries,
bleeding

Degeneration occurs at any age, but more often it is observed in 2-13% of cases. Therefore, in any case, diagnosis and observation by specialists is required.

Diagnosis of nevus

The purpose of the study is to determine whether the formation consists of benign cells or not.

A dermatologist or oncologist must take a medical history. This allows you to find out the age when the mole appeared, as well as whether changes occurred with it or not.

A visual examination preliminarily determines the type of formation. Further actions will depend on this.

Hardware diagnostic methods include:

siascopy.

The first method is carried out using a dermatoscope, which combines a magnifying glass and a camera. With its help, the neoplasm is studied in detail.

Before the procedure, a special product is applied to increase the transparency of the mole. This allows you to study the deep layers.

The method determines whether this formation is benign or not with an accuracy of 97%.

A biopsy is performed in situations where it is difficult to differentiate the formation. In such a situation, it is excised. Often the study is carried out with a mole that has already been removed. Injury to a nevus can lead to degeneration of the formation.

Siascopy allows you to obtain a diagram of the location of blood vessels, as well as the amount of collagen and melanin. The method is good for collecting information about formations located in the deep layers of the skin. Using this method, melanoma is detected with 100% accuracy.

Treatment of formations

Treatment of nevus depends on the type of formation. If it is benign, then influencing it is not advisable. It is recommended to simply observe the nevus to exclude the possibility of its degeneration.

If the doctor believes that treatment is necessary, then it is proposed, which consists of excision of the formation, capturing healthy tissue and fatty tissue.

Removal methods

Radio wave removal allows no damage to healthy tissue. A radiocoagulator is used for the procedure.
Electrocoagulation involves exposure to electric current. In this case, thermal damage to the formation occurs.
Cryotherapy is not always indicated. Fabric destroyed by cold remains in place. A crust gradually appears, protecting the damaged area from infections.
The laser allows you to work only with the affected area and accurately direct the beam to the right place. Healthy tissues are practically not damaged.
The surgical method is used for large or deep formations, if oncology is suspected.

Folk remedies

Doctors do not recommend removing nevi on the body yourself using folk remedies, since the consequences of such manipulations are unpredictable.

For the effect, celandine juice is used, which is applied to the mole. The procedure is repeated several times a day.

Among the folk remedies are garlic juice, figs, hemp oil, apple cider vinegar, honey and others.

The effectiveness of these components has not been proven; long-term exposure and constant monitoring of the mole are required to obtain results.

Prevention of malignancy

All nevi should be examined by a doctor. Melanoma-dangerous ones are removed immediately, which prevents them from degenerating into oncology. For a more accurate result, 5-10 mm of healthy tissue is captured. If necessary, plastic surgery is performed after the procedure.

The catalyst for malignancy can be constant friction with clothing or shoes, injury, abrasions. Therefore, as a preventive measure, it is recommended to carefully monitor the place where the nevus appeared. It should not be exposed to sunlight. It is worth using sunscreen before going out into the sun.

Prevention – timely detection of precancerous forms. For this purpose, dynamic monitoring and timely removal of such nevi are carried out.

Video about types of nevi: