Lentigo is a benign local melanocytic hyperchromia of the skin with possible malignancy. It is manifested by small, often multiple flat formations of brown color with clear boundaries and slow growth. Lentigo is localized in open areas of the skin: face, neck and limbs. There are several variants: simple, youthful, senile, sunny (against the background of hyperinsolation), genodermatosis. The peculiarity of lentigo is its aesthetic component, which violates the quality of life of patients under the condition of the prevalence of the process. The disease is diagnosed clinically and dermatoscopically. Treatment – cosmetic procedures, surgical excision of the formation.
General information
Lentigo is a benign neoplasm of the skin in the form of lentils, consisting of melanocytes, characterized by slow growth and the ability to spontaneous malignancy. Lentigo has no age, gender and racial restrictions, is not endemic, but is more common in Europeans with fair skin. Extremely widespread. In practical dermatology, it is customary to pay attention to the fact that multiple lentigo can be combined with genodermatoses, which are based on damage to the cardiovascular system. Taking into account this circumstance, when identifying multiple formations, consultations of a geneticist, a cardiologist and a rheumatologist are shown.
Of great importance is the possibility of degeneration of lentigo into melanoma, which is observed in about 3% of cases of the disease. Dermatologists name several risk factors for malignancy: more than three sunburns during the patient’s lifetime, a combination of lentigo with banal skin freckles, the presence on the skin surface of more than three atypical (color, size, shape) nevi from melanocytes. The urgency of the problem is associated with the possibility of uncontrolled malignancy of the process.
Causes
There are many reasons for the formation of lentigo. Among the predisposing factors, it is worth noting UFOs, mutations, the effect of artificial radiation sources on the skin, light skin tone, the use of cosmetics containing oxidized components, cosmetic procedures, age, the state of the body’s defenses, hormonal shifts (puberty, pregnancy, taking contraceptives), viral transmission of the human papilloma pathogen and the use of immunosuppressors for vital indications.
The mechanism of lentigo formation is not completely clear, since there are extremely many dermatoses that occur with the participation of skin pigment cells. Lentigo refers to melanodermal formations, which are based on the process of hyperpigmentation. Pigmentation itself is associated with biochemical reactions occurring in the skin. Melanin is enzymatically synthesized in melanocytes located in the basal layer of the epidermis, and then transmitted through the processes of cells to keratinocytes, in which it accumulates evenly, determining the color of the skin. Further, under the influence of endo- and exogenous causes, the process of hyperpigmentation is triggered – intensive accumulation of pigment by individual locally grouped keratinocytes.
Hyperpigmentation can be primary (on unchanged skin) and secondary (against the background of the involution of primary elements already present on the skin). In the case of lentigo, there is a mixed accumulation of pigment associated with hereditary predisposition, hormonal shifts, inflammation, sun exposure and age-related skin changes. The mixed nature of pigmentation is the main difference between lentigo and freckles and vulgar pigment spots, since hyperkeratosis occurs during skin aging, which thickens the primary hyperpigmented erythema and makes it noticeable to the touch.
Classification
In modern dermatology, there is a clear division of lentigo into congenital and acquired forms. In this regard, it is customary to distinguish several types of the disease. The acquired varieties of lentigo are represented by the following forms:
1 Simple forms of lentigo that have no direct connection with solar irradiation, formed against the background of metabolic disorders and hormonal restructuring of the body:
- Senile (hepatic) lentigo, which occurs due to metabolic disorders of a senile nature, accompanied by pronounced processes of hyperkeratosis and hyperpigmentation.
- Juvenile (childish) lentigo, unrelated to solar irradiation, arising spontaneously due to a violation of the hormonal background of the patient, accompanied by the process of primary pigmentation with minimal hyperkeratinization processes.
- Lentigiosis of the mucous membranes, characterized by a rash of light flat spots on the mucous membranes.
2 Solar lentigo, which has a clear cause of increased pigmentation in the form of UFO. Elements of the disease appear after sunburn, more often in people with white sensitive skin:
- Lentigo, acquired in vivo.
- Lentigo that occurred during or after a course of PUVA therapy.
- Lentigo is inky (reticular melanotic), manifested by “ink drops” randomly scattered over the surface of the skin exposed to sunlight.
Genodermatoses include several rare diseases related to genetic abnormalities:
- Central lentigiosis of Touraine is a genodermatosis of an autosomal dominant type of inheritance. Elements of lentigo appear spontaneously for no particular reason throughout life, localized on the face. Touraine’s lentigiosis is considered a harbinger of epilepsy, enuresis, and lag in the mental and physical development of the child.
- Periorific Touraine lentigiosis is a hereditary pathology, the distinguishing feature of which is localization around the mouth opening and on the red border of the lips with a transition to the mucous membranes. It can be combined with polyposis of the gastrointestinal tract, which indicates a possible spontaneous malignancy. Removal of polyps leads to regression of lentigo.
- L.E.O.P.A.R.D. syndrome is a genodermatosis of an autosomal dominant type of inheritance, manifested by multiple lentigo rashes up to 3 cm in diameter, slightly rising above the skin surface, combined with cardiac pathology, deafness and growth retardation.
- McCune-Albright syndrome is a genodermatosis characterized by a triad of signs: lentigo, endocrine gland dysfunction, bone dystrophy.
Symptoms
The clinical picture of simple lentigo consists of the formation of foci of hyperpigmentation with the phenomena of small hyperkeratosis on unchanged skin. In each focus there are brown pigment spots, slightly rising above the level of healthy skin. The shape of the spots resembles lentil grains, the number and size of formations may vary. With lentigo on the face, its occurrence can be clearly correlated with other symptoms of photodamage of the skin. The structure of elastic fibers of the dermis is disrupted, peeling spots of actinic keratosis appear. With lentigo, against the background of photochemotherapy, spots are formed not only on the face, but also on the torso, they resemble pigment spots.
Lentigo rashes do not cause negative sensations, they are painless, not prone to ulceration and scarring. Over time, lentigo begins to spread over the entire surface of the skin, especially in the extremities, back and genitals, which is associated with age-related aging of the dermis and its components (collagen and elastic fibers, intercellular matter, epidermis cells), impaired lipid metabolism and permeability of the cells of the stratum corneum of the epidermis. An increase in size, a change in the color of non–uniform formations to a darker one, a sharp thickening (bulge) and compaction of spots are marker signs of possible malignancy of lentigo into the most malignant tumor – melanoma.
Diagnostics
The use of special instrumental methods in the dermatological diagnosis of lentigo is not required. The doctor makes a clinical diagnosis based on anamnesis, symptoms, dermatoscopy data (photographing a non-visible formation in high resolution in good light) and histology results. A biopsy is necessary to confirm the absence of atypical cells that are harbingers of malignancy. A reliable proof of the benign nature of the disease is a blood test for protein cancer markers.
The risk of malignancy can also be assessed by analyzing fibroblast growth factor (heparin-binding proteins) and vascular growth factor (platelet growth factor is the basis of vascular neoplasm). Malignancy can be eliminated by confocal laser scanning microscopy (CLSM), in which the laser is used as a light source to obtain an image of a layered skin section. The method is highly accurate and has no contraindications. Differentiate lentigo, first of all, with banal freckles, birthmarks, moles, senile keratosis, chloasma, melanoma, Dubrey’s melanosis and Recklinghausen’s disease.
Treatment
Simple cases of lentigo do not require treatment if they do not cause aesthetic inconvenience and do not violate the quality of life of the patient. The observation of a dermatologist is shown. Elements undergoing repeated injury are subject to surgical removal or cryodestruction. Methods of treatment of lentigo are similar to the elimination of freckles and include daily skin whitening, photoprotection, professional cosmetic manipulations for the purpose of destruction and removal of formations.
After consultation with a dermatologist, cosmetologist and oncologist, bleaching agents (azelaic acid, retinoids) are prescribed. Photoprotection is carried out by individual selection of sunscreens with UV filters. Cosmetic manipulations include retinol peeling and laser skin resurfacing. Senile lentigo is removed by photo–rejuvenation – by exposing the deep and superficial layers of the skin to pulsed light that restores collagen and elastic fibers. At the slightest suspicion of malignancy, it is necessary to contact an oncologist to clarify the diagnosis and subsequent treatment of the neoplasm.
Prognosis and prevention
The prognosis of lentigo depends on the mitotic index – the ratio between dividing cells and the total number of cells in the field of vision. The lower this indicator is, the more favorable the prognosis in terms of malignancy, metastasis and survival. Prevention consists in dosed exposure to the sun using sunscreens. All patients with lentigo should avoid injury to formations, carefully monitor the change in color and size of “freckles” and the presence of periodic bleeding from spots. If these signs are detected, you should contact a dermatologist.