Seborrheic dermatitis is a skin disease triggered by the vital activity of certain types of yeast fungi. The area of inflammation, as a rule, extends to areas with a large number of sebaceous glands. As a result, seborrheic dermatitis on the body is less common than on the scalp, but has the same causes and characteristic symptoms.
The risk of the disease directly depends on two factors: immunity and sebum secretion. Such dependence causes the fact that seborrheic dermatitis can not be attributed to infectious diseases. Fungi that provoke an inflammatory reaction and desquamation of the epidermis (Pityrosporum orbiculare and Pityrosporum ovale of the genus Malassezia) are conditionally pathogenic and are part of the normal microflora of human skin.
Active reproduction of yeast leads to the fact that they concentrate around the ducts of the sebaceous glands and use secreted secretion as a source of nutrients. Excessive sebum exacerbates the problem.
Recycling triacylglycerides from gland secretion, fungi leave waste products – unsaturated fatty acids. Some of them can cause inflammation, irritation and exfoliation of the skin. As a result, the protective function of the skin is weakened, contributing to the further spread of pathogens.
If the epidermis is damaged and cracks appear, a bacterial infection can join the fungal infection, causing even more irritation and damage to the skin.
In rare cases, seborrheic dermatitis is a congenital abnormality, that is, a consequence of genetic susceptibility. But more often patients with acquired disease become patients of a dermatologist. Various factors can provoke a decrease in immunity and excessive secretion of fat. These include:
- hormonal disruptions, accompanied by a decrease in the level of estrogen while maintaining or increasing the concentration of androgens and progestins (inflammation of the ovaries, menopause, seminoma, androsteroma, Itsenko-Cushing syndrome, obesity);
- improper diet with excess fat, salt and spices;
- smoking and drinking in large quantities;
- infectious processes in the body;
- immunodeficiency states (in case of HIV infection, helminthic invasions, diabetes mellitus);
- taking medications (immunosuppressants, Zimetidine, Fluorouracil);
- lack of sleep, overwork;
- sweating, wearing warm clothes;
- pathologies of the endocrine system and gastrointestinal tract, metabolic disorders;
- mental disorders accompanied by malfunctions of the pituitary and hypothalamus (schizophrenia, epilepsy, MDR).
External factors can also contribute to the development of seborrhea: low temperature and air humidity, climate change, irregular hygiene procedures, the use of alkaline skin care products, laser and acid peels.
Depending on the intensity of the sebaceous glands, seborrhea manifests itself in several forms:
- Dry It is associated with a high density of the sebaceous secretion, which leads to the difficulty of its secretion, the lack of lubrication of the skin surface, irritation, flaking and the formation of small white dry scales on the body, which actively exfoliate.
- Oily. The sebaceous glands become more active, as a result of which the surface layer becomes shiny, shiny, flakes and crusts of yellowish tinge form on it. In the case of a liquid form of the disease, the skin becomes coarse, acquires a strong shine, and is often covered with acne. With thick oily seborrhea, the sebaceous ducts are dilated, comedones arise, large yellowish scales separate from the skin.
- Mixed Implies the appearance of areas with symptoms of oily and dry seborrhea. As a rule, oily skin is observed on the scalp, and a dry form is observed on the trunk and extremities..
There are several clinical forms of pathology:
- seborrheic eczematid;
- perinasal erythema (manifested on the face);
- spotted seborrheic dermatitis.
Seborrheic eczematid and spotted dermatitis are distinguished by their tendency to chronic course and spread throughout the body.
When localized seborrhea on the hands, back, neck and legs on the skin, there are characteristic red spots with clearly defined contours. Their appearance is accompanied by severe itching, especially with dermatitis in adult patients. On the surface of the spots can be seen peeling or layering of flakes of the separated epidermis.
Seborrheic dermatitis on the hands, as a rule, dry type. The onset of the disease is characterized by a feeling of tightness of the skin.
The following symptoms are observed:
- strong peeling of the skin on the hands, as seen in the photo below;
- burning sensation in the affected areas;
- dryness, not compensated by cosmetics with nourishing properties;
- maculopapular rash (with oily seborrhea), the appearance of annular, monetiform and garland-like plaques;
- gradual expansion of the area of inflammation;
- thickening of the stratum corneum;
- the appearance of large red spots that itch badly;
- frequent bleeding when scratching the affected areas.
Most of the signs are aggravated by sudden changes in temperature (for example, when moving from cold to a warm room with dry air), intense physical exertion and emotional stress. Peeling increases when working with household products, after washing hands.
Many patients believe that irritation and peeling of the epidermis occurs due to exposure to chemicals. They are unaware of the presence of a fungal infection and are trying to solve the problem with the help of cosmetics and home remedies. However, if untreated, the lesion area increases, and the itching increases. Pathogenic streptococci and staphylococcus, resulting in bacterial pyoderma and ulceration, are found in the wounds that appear during combing..
In rare cases, seborrheic dermatitis can manifest itself not only on the back of the hands and forearms, but also on the elbows, if there has been a rapid reproduction and spread of Malassezia fungi. When peeling the skin on the elbow for seborrhea mistakenly take psoriasis, which has similar symptoms. In this disease, red spots with clear edges also appear on the skin, but the scales do not have white or yellow, but a silvery shade.
On the legs, the seborrheic zone is located in the region of the legs. A very large amount of sebaceous glands is concentrated on this area. The situation is complicated in the cold season because of wearing tight warm clothes.
A characteristic sign of seborrheic lesions on the legs, the photo of which is presented below, is a bright red maculopapular rash. On the periphery of the affected area is surrounded by skin covered with scales. The secret of the sebaceous glands in this case is viscous. With secondary infection, treatment is significantly complicated.
Oily and dry seborrhea can be observed on the neck. A large number of sebaceous ducts are concentrated on the area under the hairline, therefore disturbances in the secretion of skin secretion often provoke peeling, crusts and irritation on the neck. In addition, the neck is actively sweating, which increases the risk of fungal reproduction.
On this part of the body, seborrheic dermatitis is manifested not only by irritation and inflammation, but also by the appearance of acne, acne, comedones, enlarged pores. Dry type of disease is less common. Its characteristic features are severe itching of the skin and peeling with white flakes similar to dandruff.
As a rule, seborrheic dermatitis covers not only the neck, but also the face or scalp.
The back is an inaccessible area for self-diagnosis, so patients often miss the first symptoms of the disease – redness and slight desquamation.
With the manifestation of burning and itching, the patient begins to feel discomfort and with the help of relatives or a mirror he finds red spots – a clear sign of seborrheic dermatitis. The cause of the unpleasant symptoms is the fungus Pityrosporum orbiculare, tropic to the sebaceous ducts of the back and chest.
The greatest concentration of glands is observed in the interscapular region, so rashes and suppuration occur exactly there.
A thick subspecies of seborrhea develops on the back, which is characterized by the following features:
- the emergence of comedones;
- a change in skin tone to a dirty gray or brownish;
- acne pustular, indurativnogo, drain, rarely – phlegmonous type;
- scar formation after acne healing.
Manifestations of seborrheic dermatitis not only look unpleasant, but can also lead to severe dermatological pathologies. Complications of the disease include:
- skin cracks;
- purulent tumors (when infected with staphylococci and streptococci);
- the appearance of weeping lesions;
- the occurrence of erythroderma (reddening of large areas of the body), requiring immediate treatment and medical supervision;
- the appearance of confluent (conglobate) forms of acne, which are difficult to treat.
The latter complication occurs when the upper layers of the subcutaneous fatty tissue are involved in the inflammatory process.