Skin

1. Lt Col Sameena Kausar
MBBS,FCPS(DERM), CHPE (NUMS)
Assisstant Professor of Dermatology

2. • What is the largest organ of the body?

3. PARTS OF SKIN
• Epidermis
-Ectodermal in origin
• Dermis
- Mesoderm in origin
- Divided into papillary
and reticular dermis

4. Layers of skin

6. EPIDERMIS
• Stratum corneum - Horny layer
• Stratum lucidum- Palms and soles
• Stratum granulosum- Granular layer
• Stratum spinosum -Pickle cell layer
• Stratum basale - Basal layer

8. DERMIS
• Connective tissue... Collagen & elastic fibres
• Cells... WBC, Mast cells, fibroblasts
• Skin appendages...Hair follicle, sebaceous gland, Eccrine
apocrine gland, Hair and nail
• Blood vessels
• Nerves
• Lymphatics

10. PILOSEBACEOUS UNIT

12. What is the importance of skin?

13. FUNCTION OF SKIN
Protection:
• Physical and mechanical barrier to skin
• Barrier to chemical hazards
Regulation of body temperature:
• Regulate water loss and prevent dehydration
• Maintain body temperature
Photoprotection:
• Protect excessive ultraviolet exposure via melanin

14. FUNCTION OF SKIN
Immunity:
• Antigen presentation by Langerhans cells
Metabolic function
• Production of vitamin D
Sensory and autonomic function
• Meissners & Pacinian corpuscles
• Pain, heat and cold receptors
Sociosexual & cosmetic function

15. Lesions Of Skin

16. TYPES OF LESIONS
Primary Lesions
Secondary Lesions
Tertiary Lesions

17. PRIMARY LESIONS
Definition :
• lesion occurring on non pathological skin
which have not been altered by trauma,
manipulation (scratching, scrubbing) or
natural regression over time

18. Examples
• Macule
• Papule
• Patch ???
• Plaque
• Nodule
• Wheal
• Vesicle
• Bulla
• Pustule
• Cyst

19. MACULE
Definition :
• Flat, circumscribed skin discoloration that lacks surface
elevation or depression and less than 1 cm in diameter

20. TYPES Of MACULE
1) Hypopigmented
e.g. Tuberous sclerosis , Nevus anaemicus

21. 2) Depigmented
e.g. Vitiligo, Halo naevus
3) Hyperpigmented
• Brown or black
e.g. Freckles or Chloasma

22. Bluish-grey Macule:

23. PATCH
• Patch / Large macule ???

25. PAPULE
• Solid , well circumscbed elevated
lesion, less than 1 cm in diameter
Formed by:
1) Hyperplasia of epidermis , dermis or both
e.g. : verruca vulgaris
2) Metabolic deposits or cellular infiltrates
e.g. : Xanthelasma

26. COLOUR OF PAPULE
• Red : Psoriasis
• Pearly white : Molluscum contagiosum
• Violaceous : Lichen planus
• Coppery : Secondary syphilis
• Yellowish : Xanthelasma
• Blue/Black : Mallignant Melanoma
• Purpuric : Henoch-schönlein purpura

27. PLAQUE
•Elevated well circumscribed, more than 1 cm in
diameter ,occupying relatively large surface area
in comparison with its height above the skin
surface

28. TYPES OF SCALE
Scaly Plaque :
- Psoriasis , P rosea
Lichenified plaque :
- Lichen Simplex Chronicus
Erythematous plaque :
- Tuberculoid leprosy

29. NODULE
• Palpable solid round lesion ,usually
larger than 1cm in diameter ,
occupying relatively larger vertical
diameter as compared to suface
diameter
• Better felt

30. • e.g : Erythema nodosum, Lipoma

31. WHEALS
• Evanescent , edematous ,
platue-like elevations of
various sizes
• Usually oval or arcuate , pink to
red, surrounded by a flare of
macular erythema
• It is the characteristic lesion of
urticaria

32. VESICLE AND BULLAE
Vesicle:
• Elevated ,superficial well circumscribed
lesion containing clear fluid, less than
0.5 cm in diameter
Bullae:
• A vesicle larger than 0.5 cm
• They can arise by separation of skin at different levels
a) Intraepidermal e.g Pompholyx
b) Supra basal e.g Pemphigus vulgaris
c) Dermoepidermal eg erythema multiforme

33. Lesions may be
• Tense : Pompholyx
• Flaccid : Pemphigus Vulgaris
• Umblicated : varicella zoster

34. PUSTULE
• Well-circumscribed, elevated
lesion containing visible
purulent exudate
• Pustules are characteristic of pustular
psoriasis, pyoderma, rosacea

35. CYST
• A sac that contains liquid or semisolid material
in a well-defined cavity
Types of cyst:
• Epidermal cyst: lined with squamous
epithelium and produce keratinous material
• Pilar cyst

37. ABSCESS
• An abscess is a collection of pus below the
skin
• Pus in an abscess is invisible but clinically
be interpreted as sign of inflammation in
the overlying skin
• Abscess cavities do not have well-defined
lining as cyst

39. SECONDARY LESIONS
Modification of primary skin lesions that result from
traumatic injury , evolution from primary lesion , or other
external factors
• Crust
• Scale
• Erosion
• Ulcer
• Fissure
• Scar
• Atrophy
• Telangiectasia

41. CRUST
• A collection of cellular debris,
dried serum, pus or blood and
sometimes bacterial debris
• Antecedent primary lesion is
usually a vesicle, bulla or
pustule

42. EROSIONS
• Partial focal loss of the
epidermis alone
• Heals without a scar
• Herpes zooster, TENS,
Pemphigus

44. SCALE
• Abnormal shedding or accumulation
of the stratum corneum in visible
flakes is called scaling
Causes:
• Formation of epidermal cells is rapid
• Process of normal keratinization is
interferred with

45. TYPES OF SCALE
• Fine and delicate : P. versicolor
• Coarse : eczema
• Stratified : Psoriasis

46. ULCER
• A full-thickness, focal loss
of epidermis along
with parts of dermis ,
heals with scarring
• e.g : bed sores , Syphilis
Diabetic foot, venous
ulcer

47. FISSURE
• Linear cleft in the skin through the
epidermis and part of dermis
• May be single or multiple ranging from
microscopic to a few millimeters having
well defined margins
• They occur most commonly when skin is
dry and thickened due to inflamation

48. SCAR
• A collection of new connective tissue,
that replaces lost substances in the
demis or deep dermal tissues
• They may be atrophic or hypertrophic
• Hypertrophic scars / Keloid develop
when fibrous components
predominate

49. EXCORIATION AND ABRASION
• Punctate or linear abrasion produced
by mechanical means usually involving
only the epidermis
• Caused by scratching with fingernails
in a variety of disease e.g : atopic
dermatitis, Scabies

50. ATROPHY
Reduction in the components of a tissue, Organ or
part of body. In the skin
1) Epidermal Atrophy: results from decrease in
epidermal cells .Gives rise to frequently transparent
epidermis and alteration of skin surface i.e. loss of
normal skin lines and fine wrinkling
2) Dermal Atrophy: results from decrease in the
reticular or papillary dermis. Clinically seen as
depression of skin

51. LICHENIFICATION
• Focal area of thickened skin
produced by chronic scratching or
rubbing
• Clinically triad of accentuation of
skin markings ,thickening of
epidermis and Hyperpigmentation
• e.g : lichen Simplex Chronicus
usually seen superimposed on
pruritic conditions

52. SPECIAL LESIONS
• Lesions that are pathognomic to certain skin
conditions

53. TARGET LESIONS
• Pathognomic to erythema multiforme
Three zones:
• Central, dark sometimes blister
• Pale edematous zone
• Zone of erythema

54. MILIA
• Milia are small superficial
cyst with an epidermal
lining
• Commonly seen in
neonates and children
• Especially in periorbital
areas

55. BURROW
• Serpinginous tunnel in the skin
made by scabies mite
• About 5mm in length
• Scabies