Morphology of skin lesionsMorphology of skin lesions
Dr Mesfin HunegnawDr Mesfin Hunegnaw
Consultant Dermatologist & VenerologistConsultant Dermatologist & Venerologist
AAU, Medical facultyAAU, Medical faculty
Dept. of DermatovenerologyDept. of Dermatovenerology
Morphology of skin lesionsMorphology of skin lesions
Type of the lesion,Type of the lesion,
Size of the lesion,Size of the lesion,
Shape of the lesion,Shape of the lesion,
Distribution and arrangement,Distribution and arrangement,
Leads toLeads to DIAGNOSIS.DIAGNOSIS.
Types of skin lesions…Types of skin lesions…
-Asymmetrical- exogenous cause,-Asymmetrical- exogenous cause,
-Symmetrical- endogenous cause.-Symmetrical- endogenous cause.
Exantum:Exantum: widespread cutaneous eruption,widespread cutaneous eruption,
Enantum:Enantum:when there is mucosal involvement.when there is mucosal involvement.
--The original uncomplicated patternThe original uncomplicated pattern
Macule, papule, nodule, pustule, vesicle, bullae,Macule, papule, nodule, pustule, vesicle, bullae,
wheals, erythema.wheals, erythema.
--With further development like infection, trauma,With further development like infection, trauma,
Scale, plaque, crust, fissure, erosion, ulcer, scar,Scale, plaque, crust, fissure, erosion, ulcer, scar,
lichenification, atrophy.lichenification, atrophy.
Primary skin lesions:Primary skin lesions:
‘‘macula’: ‘spot’macula’: ‘spot’
Flat, change in skin colour,Flat, change in skin colour,
No elevation or depression,No elevation or depression,
Not identified by mere touch,Not identified by mere touch,
<1.0 cm= macule,<1.0 cm= macule,
As a result of:As a result of:
Hyper pigmentationHyper pigmentation
- Cafe-au-lait spots,- Cafe-au-lait spots,
- Post inf. hyper pigmentation.- Post inf. hyper pigmentation.
Hypo pigmentationHypo pigmentation
- post inf. Hypopigmentation,- post inf. Hypopigmentation,
- Leprosy,- Leprosy,
- Vitiligo.- Vitiligo.
Vascular abnormalityVascular abnormality
- Erythema Vs pupura- Erythema Vs pupura
Macules + fine scales= maculosquamousMacules + fine scales= maculosquamous
- P.versicolor- P.versicolor
- P.rosea- P.rosea
TelangiectasiaTelangiectasia: permanent dilatation of: permanent dilatation of
‘‘Papula’: ’pimple’Papula’: ’pimple’
Small solid elevation,Small solid elevation,
Most of the its part is above the plane unlike nodule,Most of the its part is above the plane unlike nodule,
<0.5cm in diameter,<0.5cm in diameter,
Epidermal, dermal or combined changes.Epidermal, dermal or combined changes.
‘‘Nodulus’: ‘small knot’Nodulus’: ‘small knot’
Palpable, solid, round lesion (big papule).Palpable, solid, round lesion (big papule).
Felt > seen.Felt > seen.
According to anatomy:According to anatomy:
-Epidermal….Verruca vulgaris,-Epidermal….Verruca vulgaris,
-Epidermo-dermal: Melanoma,-Epidermo-dermal: Melanoma,
-Dermal: dermato-fibroma,-Dermal: dermato-fibroma,
-Dermal-SC: Granuloma annulare-Dermal-SC: Granuloma annulare
-SC: lipoma.-SC: lipoma.
Can have different consistency: hard/soft.Can have different consistency: hard/soft.
Color and shape can also be different.Color and shape can also be different.
Nodules of leprosy in 45 yrs EthiopianNodules of leprosy in 45 yrs Ethiopian
4-Blister (vesicle, bullae)4-Blister (vesicle, bullae)
‘‘Vesicula’- ‘little bladder’Vesicula’- ‘little bladder’
‘‘Bulla’- ‘bubble’Bulla’- ‘bubble’
Vesicle: small raised fluid filled lesion;<0.5cm inVesicle: small raised fluid filled lesion;<0.5cm in
Bullae:> 0.5cm in diameter.Bullae:> 0.5cm in diameter.
Cleavage at various levels of superficial skin.Cleavage at various levels of superficial skin.
Cleavage can be due to:Cleavage can be due to:
-Intracellular edema—HS-Intracellular edema—HS( herpes simplex)( herpes simplex)
-Intercellular edema—ACD-Intercellular edema—ACD(allergic contact dermatitis)(allergic contact dermatitis)
-Acantholysis--P.vulgaris-Acantholysis--P.vulgaris (pemphigus vulgaris)(pemphigus vulgaris)
According location of cleavage:According location of cleavage:
-Subcorneal: Impetigo, Subcorneal pustulosis…-Subcorneal: Impetigo, Subcorneal pustulosis…
-Intraepidermal: P.vulgaris-Intraepidermal: P.vulgaris
-Subepidermal: B.pemphigoids-Subepidermal: B.pemphigoids
-Dermal: Dystrophic epidermolysis bullosa.-Dermal: Dystrophic epidermolysis bullosa.
According to contentAccording to content::
-Fluid: p.vulgaris-Fluid: p.vulgaris
-Pus: impetigo-Pus: impetigo
-Blood: B.pemphigoids-Blood: B.pemphigoids
Small pus containing swelling.Small pus containing swelling.
Usually ass. with infection—from papules or vesiclesUsually ass. with infection—from papules or vesicles
But they mayBut they may develop by their own—acne, nondevelop by their own—acne, non
pyogenic bacteriapyogenic bacteria
Can be sterile---Can be sterile---pustular psoriasispustular psoriasis..
Pustules & plaques in 33 yrs EthiopianPustules & plaques in 33 yrs Ethiopian
Palmoplantar pustulosis in Ethiopian pt.Palmoplantar pustulosis in Ethiopian pt.
Also called urticaria,Also called urticaria,
Round or flat topped red, purple papule/plaque thatRound or flat topped red, purple papule/plaque that
disappears in a day or twodisappears in a day or two
Due to edema in the upper dermis.Due to edema in the upper dermis.
If lower SC = AngioedemaIf lower SC = Angioedema
insect biteinsect bite
7-Scale (squames)7-Scale (squames)
‘‘Squama’ – ‘scale’Squama’ – ‘scale’
Flakes of stratum corneumFlakes of stratum corneum
Increased Rate of production of epidermal cells and theIncreased Rate of production of epidermal cells and the
outermost desquamation layers of skinoutermost desquamation layers of skin scalescale
Grouped papules asso. with exaggerationGrouped papules asso. with exaggeration
of skin markings and thickening: eg.of skin markings and thickening: eg.LSCLSC..
11-Erosion, ulcer, wound11-Erosion, ulcer, wound
Different types of tissue loses varying in their depthDifferent types of tissue loses varying in their depth
and breadthand breadth
- Superficial loss of tissue- Superficial loss of tissue
- Confined to the epidermis- Confined to the epidermis
- Wide>depth- Wide>depth
- No scaring- No scaring
Can occur in: Ruptured blister,Can occur in: Ruptured blister,
degree burn…degree burn…
‘‘Ulcus’- ’sore’Ulcus’- ’sore’
Larger defect involving the dermis and SCLarger defect involving the dermis and SC
Occurs in damaged skinOccurs in damaged skin
Slow healer, always scarSlow healer, always scar
degree burndegree burn
-Decubitus ulcer-Decubitus ulcer
Traumatic defect in normal skinTraumatic defect in normal skin
Heals rapidly, less scaringHeals rapidly, less scaring
Happens when tissue defect is healed by fibrous tissueHappens when tissue defect is healed by fibrous tissue
Can be :FlatCan be :Flat good surgerygood surgery
DepressedDepressed acneacne ((Ice peak scar,Boxcar scar,Rolling scarIce peak scar,Boxcar scar,Rolling scar))
Thinning of the skin.. Epidermis, dermis or bothThinning of the skin.. Epidermis, dermis or both
Epidermal : Thinning of epidermisEpidermal : Thinning of epidermis
Transparent—visible vesselsTransparent—visible vessels
Loss of skin textureLoss of skin texture
Dermal: loss of CTDermal: loss of CT
: Depression: Depression
Area of predilectionArea of predilection
Can be :Can be :
Widespread/disseminated :Chicken poxWidespread/disseminated :Chicken pox
Diffuse—involving wider area with no interveningDiffuse—involving wider area with no intervening
normal skin: erysipelasnormal skin: erysipelas
Solitary Vs multipleSolitary Vs multiple
Multiple ones : grouped Vs random arrangementMultiple ones : grouped Vs random arrangement
Grouped: HS, DH…Grouped: HS, DH…
Linear: epidermal nevusLinear: epidermal nevus
Follow skin folds……P.roseaFollow skin folds……P.rosea
Exact measurement of the lesions onExact measurement of the lesions on
cm or mmcm or mm
Two perpendicular diameters –oneTwo perpendicular diameters –one
representing the max. lesion sizerepresenting the max. lesion size
Border of the lesionBorder of the lesion
Sharp Vs indistinctSharp Vs indistinct
Active/scaly----fungal infn.Active/scaly----fungal infn.
Clinical testsClinical tests
Patch testPatch test
-Allergic contact dermatitis-Allergic contact dermatitis
-Identify the allergen-Identify the allergen
Photo patch testingPhoto patch testing
-To determine photo allergy-To determine photo allergy
Prick testingPrick testing
-Determine type 1 allergy-Determine type 1 allergy
Aceton whitingAceton whiting
-Sub clinical penile or vulvar warts, 5% acetic acid-Sub clinical penile or vulvar warts, 5% acetic acid
Photo testingPhoto testing
-Which WL of UVR causing photo induced illness:-Which WL of UVR causing photo induced illness:
PMLE, AP, HV…PMLE, AP, HV…
Hand lensHand lens: better, closer visualization: better, closer visualization
- LP- LP wickham's streawickham's strea
- SLE- SLE follicular pluging and atrophyfollicular pluging and atrophy
- Scabies-mite- Scabies-mite
-Glass spatula-Glass spatula
-Lab. Slides-Lab. Slides
Erythma Vs purpuraErythma Vs purpura
Wood’s lampWood’s lamp
-Uses black light-Uses black light
-Hair, skin diseases-dermatophytes of the hair shaft-Hair, skin diseases-dermatophytes of the hair shaft
P.versicolour, Erythrasma…P.versicolour, Erythrasma…
-Urine exam for porphyria-Urine exam for porphyria
-Penetrate 2-3mm-Penetrate 2-3mm
-Ass. skin thickness—sceleroderma-Ass. skin thickness—sceleroderma
-Ass of effect of steroids on the skin-Ass of effect of steroids on the skin
-Flow of blood-Flow of blood
KOH:KOH: different fungal infectionsdifferent fungal infections
Gram stainGram stain with culture and sensitivitywith culture and sensitivity
Dark field:Dark field: T.pallidum detection.T.pallidum detection.
Tzank preparation:Tzank preparation: HS,HZHS,HZ
Gaint multinuclated cells,Gaint multinuclated cells,
Wet mount,Wet mount,
Indian ink…Indian ink…
Used for evaluation of infectious andUsed for evaluation of infectious and
autoimmune diseasesautoimmune diseases
Doubt about diagnosis-biopsy should be doneDoubt about diagnosis-biopsy should be done
The slightest doubt that a lesion could be a malignancyThe slightest doubt that a lesion could be a malignancy
is an indication for biopsyis an indication for biopsy
Area: fresh lesion, where healing is goodArea: fresh lesion, where healing is good
Simple excision (excisional biopsy)Simple excision (excisional biopsy)
.for simple lesions.for simple lesions
Punch biopsyPunch biopsy
Shave, tangential biopsyShave, tangential biopsy
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