Elemental skin injuries

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Diagnosis in dermatology is based, as in other medical specialties, on interrogation, physical examination and further investigations

The tegument is often the mirror of internal diseases; the discovery of skin signs, easily accessible to semeilogical analysis and biopsy, can thus spare the patient from other expensive or uncomfortable explorations

“basic lesions” are the skin’s response to different diseases and aggressions it suffers

the lesion must be able to be individualized fairly easily without being confused with another lesion

These elementary lesions are an “alphabet” that the doctor must learn to read in order to be able to diagnose a disease that affects the skin

We propose to classify elementary lesions primarily as: according to the following two criteria

  • Whether or not the lesion is palpable.
  • the presence of alteration on the surface of the lesion.

Primary injuries:

are the lesions that appear de novo and reflect the initial lesion process.

A- Non-palpable lesion: macule

This is a visible but not palpable lesion

It is the result of a localized change in the colour of the skin without visible alteration of its surface (without reliefs)

Size: usually ranges from 5 to 20 mm

may result from an anomaly in:

  • epidermis example:vitiligo
  • the dermis example: petechia
  • epidermis and dermis example: post-inflammatory hyperpigmentation
  •  Macules can be categorized according to their color and the effects of vitropression By:

1) dyschromic macules: which can be:

  • example white: vitiligo
  • example pigment: lentigo
  • blue-grey example: Mongolian spot
  • yellow example: xanthome plane
White or achromic macule with repigmentation islets around the hair follicles during a vitiligo.
White or achromic macule with repigmentation islets around the hair follicles during a vitiligo.
Senile lentigos on the dorsal side of the hand.
Senile lentigos on the dorsal side of the hand.
Mongolian stain
Mongolian stain

2) erythematous macules:

Red macules deserve special mention because of their semiological peculiarities and frequency.

They may result from active or passive vasodilation (e.g. exanthema, cyanosis) or intravascular blood accumulation (e.g. angioma).

They then disappear with vitropression, as opposed to purpuric macules that result from extravascular deposits of red blood cells and persist in vitropression.

1- Erythema:

is localized or diffuse redness of the skin, fading to vitropression, permanent or paroxysmal,

The colour varies from pale pink to dark red.

Diffuse erythema often combines flat lesions with palpable papule lesions and/or plaques, thus achieving, when it is of sudden appearance, a maculopapulous exanthema.

erythema 2

erythema 1





We’ve got:

Morbiliform exanthema: consisting of red macules that tend to confluent while respecting healthy skin intervals.

The scarlatiniform exanthema: it is an intense, diffuse redness, which confluences without leaving a healthy skin interval and gives the impression of a granite to palpation.

Scarlatiniform erythema
Scarlatiniform erythema
Morbilliform erythema
Morbilliform erythema





Roseola: it is a well-individualized pink lesion usually measuring less than 02 cm ex: syphilitic roseola.

Erythrodermia: a diffuse erythema, of prolonged, severe evolution, affecting more than 90% of the body surface, accompanied by peeling or very quickly.








2- Cyanosis:

it is a purplish blue coloration of the skin with decreased local temperature affecting the extremities and mucous membranes that confluences without intervals of healthy skin.


3- Vascular macule: non-palpable red lesions correspond to a permanent dilation of the small vessels of the superficial dermis and/or an excess of the number of capillaries:

telangiectasies: it is non-palpable red lesions corresponding to a permanent dilation of the small vessels of the superficial dermis in the form of small sinuous lines of a few mm emptying to the vitropression.

Poikilodermia: it is the association of skin atrophy and reticulated pigmentation and telangiectasies.

The plan angioma: congenital lesion, variable size, chronic throughout life, dark red, although limited.

Telangiectasies resulting from a dilation of the superficial vessels of the dermis and disappearing to vitropression.
Telangiectasies resulting from a dilation of the superficial vessels of the dermis and disappearing to vitropression.
Angioma plan
Angioma plan

4- Purpura: it is a permanent redness that does not erase the vitropression showing an intra-skin hemorrhagia.

Purpura can be circumscribed or extended and go through different shades ranging from red to blue to green to yellow to allow a brown sequelle to persist in a transient or lasting way.

Petechiae: it is limited purpuric lesions of small dimensions

vibices: it’s purpuric linear streaks – /-wide and elongated

bruising: An extended purpuric plaque with an irregular contour, often with a variety of complexions.

Purpura petechial
Purpura petechial
Purpura in vibices
Purpura in vibices







3) atrophic macule:

it is a non-palpable lesion that can retain a normal color but become visible due to an unusual transparency of the skin, revealing the vessels, becoming smooth and finely wrinkled thus taking on an appearance in “cigarette paper”

B- Palpable lesions:

They are noticeable when the pulp of the fingers is walked parallel to the surface of the teguments, exerting variable pressure, even though they are sometimes invisible.

There are several types of palpable lesions that can be distinguished by:

  • depending on their content (liquidor or solid).
  • And their size.
  • And their skin location (superficial or deep).

1) Solid injuries:

a) Papule: is usually defined as a small, non-liquid ian palpable lesion.

Its size should not exceed 10 mm.

papules may be folicular or non-follicular.

papules should be distinguished from other palpable lesions that are larger (plate, nodule, tumor), located deeper (nouure), liquid content (vesicle, bubble) or that result mainly from surface alteration (horn, keratosis).

Multiple "dome" papules, confluent in places, during a papule oust.
Multiple “dome” papules, confluent in places, during a papule oust.
Papules grouped in "ring" during an annular granuloma.
Papules grouped in “ring” during an annular granuloma.

b) plate:

refers to relief lesions that are more extensive on the surface than in height and measuring more than 1 cm


c) Lichenification: consists of a thickening of the skin with exaggeration of its furrows, which makes its normal grid apparent

Linenification plate making the skin thicken with exaggeration of its furrows. Also noteworthy is the presence of linear erosions associated with scraping.
Linenification plate making the skin thicken with exaggeration of its furrows. Also noteworthy is the presence of linear erosions associated with scraping.

d) The tuber:

is a palpable intradermal lesion without (or with little) relief.

These lesions are often chronic or tend to regress to leave a scar

They are circumscribed and mobile in relation to the hypodermis.


e) The nodule:

is a palpable, non-liquidian mass, measuring more than 10 mm. nodules are dermal and/or hypodermic.

(f) tumor: any nodule-20mm without inflammatory character.

(g) knot: is a large nodule (often more than 5 cm), hypodermic extension,

Skin nodule of inflammatory cause (sarcoidosis)
Skin nodule of inflammatory cause (sarcoidosis)
Nouures scattered on both legs (noueux erythema)
Nouures scattered on both legs (noueux erythema)

h) Gum: as the knot when it is in the rawness phase passes as a result of softening and fistulaization and ultimately healing.



Growths of filiform, digitized or lobed appearance branched in soft cauliflower.

Frequent on mucous membranes or around natural holes.

The surface of the lesion is made up of a thinned and pink epidermis.


J) Verrucocity: are growths of filiform, digitized or lobed appearance, sometimes branched into cauliflower whose surface is covered with a coating, keratosic often grayish, more or less thick.

Vegetation with a keratosic surface, defining the warty during a periungueal wart.
Vegetation with a keratosic surface, defining the warty during a periungueal wart.




k ) Cordon: are lesions easily palpable evokes a rope or string, are line, more or less of very variable size.

l) Furrow: a small tunnel in the skin that usually harbours a parasite.

These are often barely visible and/or palpable millimetre lesions.

2) Injuries of liquid content:

It is a lesion that is most often palpable and lifts the skin into a cavity that contains a liquid.

Lesions with liquid content are distinguished according to their size and the appearance of the liquid


  • circumscribed skin lift
  • Size :d less than 3mm containing a clear liquid.



  • circumscribed lift of the skin.
  • Size :de over 05mm.
  • containing a clear, sero purulent or hemorrhagic liquid. They can be located on the skin, but also on the external mucous membranes (buccale, conjunctivale, nasal, genital).



1- subdermal bubbles: the roof is solid and can rest on normal, erythematous or urticarian skin.

2- epidermal bubbles: fragile, often spontaneously broken, presenting themselves as an erosion bordered by a collar.

subdermal bubbles


Relief lesion of a few mm or cm, of immediately purulent content of milky white or yellowish coloring.

Among the pustules are:

1- follicular lesion: which are acuminized by a hair (example: folliculitis)

Follicular injury

2 non-follicular lesion: generally more flat and unacumenized, intra-epidermal, very superficial, under-horned.

Multiple, non-follicular pustules on a erythematosic background
Multiple, non-follicular pustules on a erythematosic background

Skin surface alterations:

1- Erosion:

is a loss of the superficial part of the skin (the epidermis) that heals without leaving a scar.

It is a moist, oozing lesion, which is secondary to a crust.

  • Excoriation:

is sometimes used to refer to erosion secondary to trauma, most often scratching.

  • A crack

is a linear erosion.


2 An ulceration:

deeper, touches the epidermis and dermis, if it heals will leave a scar, may be covered with a fibrinal plaster, a bloody crust or a black plate.

An ulcer: loss of chronic substance with no tendency to spontaneous healing.

  • bedsores: ulcerations at pressure points.

3 A fistula:

is a skin pertuis, of varying depth, which corresponds to an abnormal communication of a deep structure on the surface of the skin.

Dental fistula
Dental fistula

4- The dander:

define themselves as slats of corneal cells on the surface of the skin.

They are not very adherent and come off easily.

They are spontaneously visible or appear after scratching with a foam-edged curette.

Depending on the thickness and appearance of the dander, one can distinguish:

  • Ichtyosiform dander: polygonal in size and shape (fish scales) e.g. hereditary ichthyoses.
Ichtyosiform Squame
Ichtyosiform Squame
  • Pityriasiform squames: small, fine, unadish, whitish and floury dander. (ex pityriasis versicolore).
  • Scarlitiniform dander: in large shreds (ex scarlet fever)
  • Psoriasiform squames: white, shiny, thick, wide and adherent; gradual scraping shows a crumbling into strips (psoriasis).
  • “Collared dander: thin, adherent to the centre but not to the periphery, covering an inflammatory lesion.
Scarlatiniform, Pytiriasiform, Psoriasiform, En collar
Scarlatiniform, Pytiriasiform, Psoriasiform, En collar


superficial drying of exudate, secretion, necrosis or skin hemorrhage.

The evolutionary stage of different primitive lesions: bubbles, vesicles or pustules.


6- Keratosis:

thickening cornea wider than thick.” very adherent and hard at palpation

7- A horn:

Keratosis thicker and taller than wide.


8. Gangrene:

A blackish tissue necrosis, unviable skin tissue that tends to eliminate, cold to palpation.


9. Scar:

Corresponds to the completion of a repair process involving mainly the dermis after a loss of substance or skin inflammation.


Changes in skin consistency:

Finally, some lesions are mainly due to a change in the consistency of the skin that becomes too much or not flexible enough.

These lesions are mostly apparent to palpation.

1)Skin atrophy:

defines the reduction or disappearance of all or part of the skin’s constituent elements (epidermis, dermis, hypodermis or

two or even three compartments).

It presents itself as a thinning of the coat that wrinkles with superficial pinching, losing its elasticity, its relief and taking on a smooth and pearly appearance.


2)- Sclerosis:

Visible and above all palpable, characterized by a thickening and loss of skin elasticity, due to condensation of the constituent elements of the dermis.

Multiple sclerosis

3)- Anetermia:

Depression at palpation. Saille at the insption .


How to confirm the diagnosis:

  1. vitro pressure.
  2. Wood’s light.
  3. application of certain substance.
  4. physical manoeuvring.
  5. scraping by a foam curette.
  6. dermatological magnifying glass.
  7. Dermatoscope.

Magnifying glass







  • In dermatology, more than in any other medical discipline, physical examination is the determining factor in the diagnostic process.
  • A perfect knowledge of dermatological semiology is therefore essential.
  • Dermatological examination should identify the elemental lesions, recognize a possible configuration and/or remarkable arrangement, and assess the distribution of the lesions.
  • This approach makes it possible to diagnose many diseases, without recourse to further examinations, a privilege rare in our time.

Prepared by: Dr. Bouhila – Framed by: Dr. Laroum

Constantine Faculty

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