Nevus - Causes, Symptoms and Treatment .MF .
Nevus (from the Latin naevus), or spiloma, birthmark, mole - malformation, which is characterized by the appearance of the skin, sometimes on the mucous membranes, the conjunctiva (the thin transparent tissue covering the eye from the outside) and vascular (average) shelleyeball (iris and choroid) spots or entities consisting of the so-called nevus cells.
nevus cells arise during fetal development of neural crest - a special set of cells, from which developed a variety of anatomical structures (ganglia, meninges, some adrenal cells and pigment cells (melonotsity) of the skin).Due to some reasons insufficiently studied nevus cells do not reach maturity melanocyte.The precursors of melanocytes (melanoblast) migrate into the deeper layer of the epidermis (the epidermis - the outer layer of human skin, represented by stratified epithelium), but some of them do not reach it, and remain in the dermis (connective tissue of the skin located below the epidermis).
nevi have been reported in 75% o
nevus in its development goes through several phases: first is vnutrieptelialnym nevus, then transformed into a border, and over the age of 30 years goes into phase intradermally.With the onset of older nevi often regress: nevus cells deep within the dermis and are subject to modifications, eventually being replaced by connective tissue.This evolution nevus associated with the steps to simplify the organization and functions of melanocytes: melanocyte - cell nevus - fibrous (fibrous connective) tissue.
much overwhelming majority of nevi are acquired is, who are divided into ordinary and special types.Among the usual nevi, in turn, allocate the border, complex (epidermal-dermal) and intradermal form.
Edge, or junctional, nevus appears, usually in the first two decades of life and is located mainly on the face, neck, torso, hands, in some cases, the external genital organs;It appears evenly pigmented (from light brown to dark brown) spot diameter of 1-5 mm and a maximum of 10 mm, having a round or oval shape, smooth surface and sharp edges.The surface boundary nevus is devoid of hair.This form of nevus there until the age of about 35 years.
Mixed or complex nevus is a transitional form from the border to the intradermal nevi.It can advantageously be advantageously borderline or intradermally.Compound nevus has a spherical shape and dense texture, its color may vary from light brown to black, size, generally do not exceed 10 mm.
intradermal nevi more common in middle or old age.It can be single or multiple, and located mainly on the face, neck or torso.Intradermal nevus looks like the dome or warty education that shape may resemble blackberries and have a "leg".Its size varies from 2 mm to several centimeters, color - from pale brown to black, but sometimes there is depigmented (containing no pigment) intra dermal nevus whitish or pinkish-red color.
From localization usual nevi in various parts of the body, and especially those in their nevus cells depend on their external manifestations: on the palms and soles, where the stratum corneum is very thick, complex and intradermal nevi do not protrude above the skin.Towering above the skin nevi are characterized by a pronounced intra dermal nevus component, and the flat - border component.The stronger nevus protrudes above the level of the skin, the less it is pigmented.
usual nevi increase in size in direct proportion to the growth of the human body.Their number increases after birth and reaches its maximum during puberty, and gradually decreases after age 50, and to the 70-90 age they tend to disappear altogether.
Congenital nevi are benign tumors of the pigment, which consist of nevus cells (derived melanoblast) arising as a result of violations melanoblast specialization process during the prenatal period.Congenital nevi are present in 1% of Caucasian children and can be detected at birth or within the first year of a child's life.They come in different sizes, up to the giant.Congenital nevi light brown or dark brown, some stand out above the level of the skin, can sometimes be covered with hair, although hair growth is not started immediately.Congenital nevi are round or oval, clear or blurry borders, regular or irregular shape.Their surface can be saved with the skin or uneven pattern, wrinkled, folded, lobed, sometimes covered with papillae, resembling gyrus.They may be located on any part of the skin.In 5% of cases these are multiple nevi, but then one of them is larger.Larger nevi are soft to the touch.Congenital nevi in appearance indistinguishable from conventional acquired nevi, the only external difference between them is the diameter of more than 1.5 cm (acquired nevi such dimensions do not reach).Large (more than 20 cm in diameter) and giant congenital nevi occupy part of the anatomical region or the whole of its (trunk, limbs, head or neck), but when combined with multiple small congenital nevi.Small congenital nevi in 95% of cases are single.Another difference congenital nevi is that nevus cells are located in the deep dermis, subcutaneous tissue in the skin appendages.Congenital nevi, unlike acquired not disappear spontaneously.
Congenital nevi face
dysplastic nevus (Clark nevi, atypical nevi) is acquired pigmented lesions, formed as a result of indiscriminate division of atypical melanocytes.It is found in 5% of the population develops on normal skin, or on the background of a complex (mixed) nevus, sometimes border.Dysplastic nevus appears later than acquired nevi - before puberty, during life, until old age, is usually on the trunk and extremities.It promotes the development of its presence in the sun.Spontaneous disappearance of dysplastic nevus is not typical.Dysplastic nevus occupies an intermediate position between the acquired nevi and superficial spreading melanoma.It looks like a spot with some towering above the skin areas, has large dimensions (more than 15 mm in diameter) and uneven coloring, which can be variegated, resemble a fried egg or a target.It is also characterized by asymmetry and irregular border, fuzzy, jagged edges.
risk of malignancy (malignancy) nevi.
very existence of human nevi creates some risk of his skin melanoma - a malignant tumor that develops from melanocytes.People with multiple small nevi, this risk is greater than average.The risk factor is not only the amount of skin nevi, but their shape and the presence of protruding above the surface.The appearance of skin melanoma is possible after injury nevi: a single (bruises, abrasions, cuts) or chronic (permanent trauma clothing or shoes).
Since 50% of cases of skin melanoma develops in the background prdshestvuyuschih nevi, they are considered as a precancerous condition.There is a direct correlation between the size of nevi and the frequency of their malignancy.
In respect of malignancy are the two most dangerous types of nevi: dysplastic and congenital.Under certain conditions displastichesie nevi can degenerate into melanoma in 100% of cases.In any of congenital nevi may also develop melanoma.
risk of malignancy nevus Bole diameter of 2 cm is 5-20%, while special danger represent nevi located on the face.A person having 20 nevi, risk of melanoma increases by 3 times.
main external difference melanoma (4 photos on the left) of nevi (4 photos on the right), from top to bottom: asymmetry, uneven contours (ragged, jagged edges), uneven pigmentation (color of various shades of black and brown), changes in cell diameter.
tactics of treatment, indications for surgical removal of nevi.
In most cases, acquired nevi do not require any treatment, but there are indications for surgical removal:
1. Cosmetic indications (on the patient's request to remove disfiguring nevus).
2. Location normal nevus in difficult places for self-control (for example, on the scalp, perineum).
3. Detection of signs of atypia nevus such as uneven distribution of melanin, the serration of its borders, its vagueness, a relatively large diameter (more than 5mm).
4. Atypical nevus development, including sudden change in shape and size.
5. Nevus with the presence of high risk of malignancy (eg, giant congenital nevi; displastichesie nevi).All small congenital nevi with an unusual appearance (uneven coloring, irregular shape, etc.) must be surgically removed before reaching the age of 12 years old patient.The operation to remove a giant congenital nevus was carried out as early as possible.
6. With prophylactically, in some cases it is expedient to remove nevi when a significant amount as it prevents the occurrence of melanoma.
7. Intensively colored nevi peripheral location in the limbs, to the mucosa in the subungual region and conjunctiva, but should be removed as an opportunity displastichesih nevi such localization is alert to their rebirth in melanoma.
8. Frequent repeated irritation and injury nevus, for example, located under the belt, bra or collar.
clearly defined and indications for immediate excision of the nevus.These are signs of a sudden change in the last month or more:
1. Increase the area and height of the nevus.
2. Increasing the intensity of pigmentation, especially in those cases where it is uneven.
3. The appearance of the corolla of pigment around the nevus, the emergence of elements of the satellite.
4. The inflammatory process in the nevus.
5. The emergence of itching.
6. The formation of erosions and bleeding occurrence.
Removing nevi should be an oncologist, be radical and conducted only surgical method with the obligatory subsequent histological examination of remote tissues.Partial removal of the nevus is unacceptable, since then nevus repigmentiruetsya and recurs, forming psevdomelanomu.Cosmetic outcome is often unpredictable in this case, such treatment may lead to recurrence of the consequences are less favorable than before treatment.
Such removal methods as electrocautery, cryotherapy, dermabrasion, laser removal of skin nevi and mucous membranes must not be used as make it impossible for histological confirmation of the diagnosis.
Removing small size nevi in adults is possible under local anesthesia and is considered a relatively simple surgical procedure, the patient does not require any prior training.After excision of the nevus on the edges formed on the skin defect closed with stitches, tightening it, on top of a few days is attached sterile dressing every day for a week held ligation, after the healing of the wound sutures are removed.Details the process of removing a nevus with photographs during the operation discussed in the article "moles, birthmarks" & gt; & gt;
in operations for large nevi that formed extensive defects of the skin, to close them resort to plastic skin and the surgery is performed under general anesthesia.
All surgeries performed in children only under general anesthesia.
Prevention malignancy nevi
Prevention of melanoma patients with nevi is an early and effective detection of predmelanomnyh forms (especially dysplastic nevus).It is necessary to allocate patients to the presence of these forms in the "at risk" and to carry out constant monitoring of the dynamic changes of these elements, or delete them.
Patients with dysplastic nevi should be aware of signs of degeneration of these nevi in melanoma and thus independently regularly monitor how they change.These patients are advised to avoid exposure to the sun, and at the exit to the street to apply sunscreen.
Surgeon Kletkin ME