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The skin is the body envelope, it is in continuity with the mucous membranes covering the body's natural cavities , it is an organ that has an area of about 2 m2 in an adult, which weighs just over 3 kg, and includes 3 million cells per cm2 About. E pidermi s: is the top layer of the skin, which it protects against external aggressions, it measures on average 0.
The epidermis contains no blood or lymphatic vessels but contains many free nerve endings. The epidermis is a multistrated Malpighian epithelium that is composed of 4 superimposed layers:. M elanocytes : are regularly distributed along the basal layer in varying amounts, have a starry appearance and their cytoplasmic extensions insinuate themselves between the keratinocytes. They lack an intercellular junction system with neighbouring cells. Melanin is the pigment produced by melanocytes in cytoplasmic organelles.
These cells gradually flatten to the surface but their nuclei and organelles remain intact. Many keratin grains and keratins appear in keratin filament kits. Cytoplasmic nuclei and organelles have completely disappeared and the cytoplasm is filled with fibrillary kits formed from keratin filaments and keratohyaline grains. On the surface, these corneocytes are eliminated in a very orderly way: this is the physiological process of peeling. From RMO-Epid e rmal junction: sep arates the epidermis from the dermis, the complexity of its structure and its functional importance make it a full-fledged one.
It appears between the basal keratinocytes and the papillary dermis as a thin and homogeneous wavy line where the protrusions of the epidermis alternate in the last so-called "epidermal crests " and the protrusions of the dermis in the epidermis known as "dermal papillas". The dermo-epidermal junction presents epidermis anchoring complexes on the dermis. D erme Latin skin : forms a well-defined barrier that gives the skin resistance to tearing and elasticity to stretching.
It is a connective organ made up of connective fibers and cellular elements, it consists of a fundamental substance, elastic fibers, collagen fibers, vessels and nerve nets. H ypodermis : Continuing the dermis to depth, the hypodermis is a loose, richly vascularized connective tissue that, depending on the nutritional conditions and regions of the skin, contains more or less adipose tissue divided into lobules by spans conjunctivas.
S weat g lands: are tiny in size, located in the thickness of the dermis or subcutaneous cell tissue, they are shaped like tubes. These are exocrine glands which release their secretion via an excretory channel that crosses the dermis, the epidermis and comes to open outside by a sweatpo , very numerous 2 to 3 million , distributed in abundance on the forehead, the p the tip of the hands, the soles of the feet, the territories of the underarms and genitals and are intended to secrete sweat.
There are two types:. The eccrine glands play a thermoregulation role in case of fever or emotional factors , in hydroelectrolytic balance and in the elimination of waste from metabolism.
P ilosebace f Polling: are made up of the hair follicle to which the sebaceous glands are applied secreting a lipid product and the arvatic muscles with segmental sympathetic innervation whose contraction under the effect of cold, fear… triggers hair straightening goosebumps. At its deep part, it adheres to a small bag called a "follicle ". There are three phases:. A nagen phase: lasts on average about days but can range from 2 to 6 years in humans and is the growth phase of the hair.
During the anagen stage, the rate of hair growth is rapid and reaches about half to an inch per month. C aTAG e n phase : lasts only 3 weeks, it is the transition or regression phase of the hair, it precedes the resting stage. During the catagen stage, the hair growth cycle slows down and then stops. T alone e nic phase I know: lasting 5 to 6 weeks, is the resting phase where the hair no longer grows but remains anchored in the follicle.
It is only at the end of this phase that the hair falls. The nail has multiple functions: protection, fixed counterpress plane in tactile pulp sensitivity, fine grip, aggressive or aesthetic role.
The moon is the whitish part of the limb, located in the vicinity of the root, it is particularly well developed at the thumbs. A nalog ap p roach: fa st, which makes the diagnosis upon inspection on a characteristic clinical aspect, it requires having already seen the lesion to recognize it and carries the risk of error.
A nalytic a l method: reasoned, is slower, it corresponds to a conventional medical approach: the collection of data analysis precedes diagnosis synthesis. It is this method that will be described here.
I nterrogation: will tell the story of the disease beginning mode: abrupt or progressive, localized or diffuse , the appearance of the initial lesion, the progression of the lesion, the evolution of the condition, functional signs pruritus and general signs.
It should also specify the concept of prior drug intake toxidermy, induced dermatosis , environmental factors occupation, habitat, sun exposure and psychological factors.
D ermat O logical exam ination: based mainly on inspection, palpation and incidental on vitropression, curettage and friction…. I dentification of th e element e ntal lesio n: size, shape, surface, consistency, colour. I dentification of f snake ed lesions: is olated or grouped punctiform, lenticular, nummular, plaques, tablecloths, universalis or a figurative grouping: linear, annular, arciform, zoniform. I dentification O f t O p ography: ub iquitous or elective discovered areas — pho t o-dermatosis, bastion areas — p so riasis — plane….
P r ugly: master symptom, either absent or present, it is important to specify its intensity, the moment of occurrence day, night, permanent, paroxysmal, effort, rest , the exact topography. A dditi O nal examines tions: in many cases, analysis of skin lesions leads to a diagnosis or a diagnostic group, but sometimes paraclinical explorations are essential.
Two sampling techniques are possible:. P unch: is a piece carry with a circular cylindrical blade that allows to obtain a skin carrot, this technique is often practiced in children because the intervention time is very reduced. B iopsy w i th you are hate: is more classic, it is done according to an incision in ellipse, carrying out a sample in the orange wedge, a secondary suture is, here, essential.
E trigger t aneous t ests: are indicated during contact eczema, especially professional. P hoto -b iolo gical tes ts: are indicated during dermatoses by photosensitization. M together: stain, lesion from a few millimetres to a few centimetres in diameter, visible but non-palpable.
Matches a simple color change:. D isappearing f r O m v itropressure : telangiectasy, erythema. P ersistent i n v itropression : purpura. A chroma t ic or whi t i s h macules : vitiligo. S that rl us if orm type: brig ht red rash, in large continuous cupboards, without intervals of healthy skin e. M or b ili f orm type: extended red rash, made of small elements with healthy skin intervals e. R the is Glamourous O rm type: is ythema made of spots, poorly delineated with wide intervals of healthy skin e.
E xulceration erosion : loss of surface substance, affecting exclusively the epidermis e. The lceration: loss of substance affecting the dermis, followed by scarring e. S quames : layer strips that stand out on the surface of the skin, are not very adhering and easily detach, they are spontaneously visible or appear after scraping with a foam-edged curette.
Traditionally, one distinguishes:. A trophy: thinning of the skin, whitish, pearly lesion, with depressed skin, finely slating e. Sc lerosis: induration of the skin, which becomes difficult to wrinkle with the erasure of relief e.
Xeroderma Pigmentosum on the same lesion. V itropressio n: is to apply a transparent object glass or plastic against the skin lesion, thus emptying it of its blood e. W ood's at the ght ex a m: is to examine the skin in ultraviolet light in the dark infectious dermatoses….
A pplication O f China s e i nk: allows you to search for scaly furrows. F irm line With stimu l atio n: using a soft tip, allows you to search for a dermographic.
S crapin g wi th a foam c wrongs e fro m Brocq : allows you to show the characteristic flaking of psoriasis. D Irmatov l O g ic a l mag n ifying glass: helps to refine the inspection. D ermatoscopy: for the examination of emersion and epi-illumination lesions, allows, after the application of a drop of oil, to carry out an inspection through the corneal layer that becomes transparent.
A canthose : is defined by an increase in the overall thickness of the epidermis, acanthose can be diffused or selectively affect the epidermal crests, in this case, the acanthose is called "psoriasiform". In the case of a selective increase in the thickness of the granular layer, it is called "hypergranulosis" , the plane lichen is the characteristic example.
H yperkeratosi s: is a thickening of the corneal layer, it can only be relative when there is a decrease in the thickness of the underlying stratum spinosum and granulosum. If keratinocytes keep their usual appearance devoid of nuclei, it is an "orthokeratosic " hyperkeratosis. A cantholyse : is characterized by a loss of the intercellular connection of keratinocytes, the cells appear isolated from each other and this leads to the formation of intra-epidermal bubbles, as in pemphigus.
This acantholyse can be seen on all levels of the epidermis. S pongios is: results in a spread of keratinocytes from each other due to intercellular edema, intercellular spaces are clear and widened, resulting in "mesh " images. P apillomatosis : results in an exaggeration of the design of the papillae and inter-papillary crests, so it is frequently accompanied by an acanthose.
D ermal a t rophy: is characterized by a decrease in overall thickness, scarcity of collagen and hypotrophy of the appendices. S clerosis : on the contrary, is defined by a thickening of collagen, which becomes very horizontal. The architecture of the skin is complex which includes several cellular populations as well as annexes.
A good clinical examination identifies the elementary lesion that is the cornerstone for diagnosis. Given the accessibility of the skin, a few additional tests can help our diagnostic process. Any semiological elementary lesion has a histological interpretation histological elementary lesion.
Genital ulcers and Uretrits. Genital ulcers and uretrits.
Basic injuries and diagnostic procedure in dermatology
The epidermis contains no lymphatic or blood vessels but contains many free nerve endings. They are devoid of cell junction system with neighboring cells. These cells gradually flatten towards the surface but their nuclei and organelles remain intact. It appears, in keratin filaments keyrings, many grains keratohyalin and keratinosomes. Nuclei and cytoplasmic organelles have completely disappeared and the cytoplasm is filled with bunches fibrillar formed from keratin filaments and grains of keratohyalin. Surface, these corneocytes are removed from very orderly : is the physiological process of desquamation. It appears between the basal keratinocytes and dermal papilla as a wavy line, fine, even where alternate the projections of the epidermis into the dermis called "epidermal ridges" and the projections of the dermis in the skin called "dermal papillae".
elementary lesions and diagnostic approach in dermatology
The skin is the body envelope, it is in continuity with the mucous membranes covering the body's natural cavities , it is an organ that has an area of about 2 m2 in an adult, which weighs just over 3 kg, and includes 3 million cells per cm2 About. E pidermi s: is the top layer of the skin, which it protects against external aggressions, it measures on average 0. The epidermis contains no blood or lymphatic vessels but contains many free nerve endings. The epidermis is a multistrated Malpighian epithelium that is composed of 4 superimposed layers:. M elanocytes : are regularly distributed along the basal layer in varying amounts, have a starry appearance and their cytoplasmic extensions insinuate themselves between the keratinocytes.