Introduction to dermatology
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Transcript Introduction to dermatology
INTRODUCTION TO
DERMATOLOGY
DEFINITION
What is dermatology :
It is the science that deal’s with the skin and study it’s diseases and
conditions
Dermatology is defined in The New Oxford Dictionary of English as ‘The
branch of medicine concerned with the diagnosis and treatment of skin
disorders’
Why we study the skin ?
Because the skin the largest organ in the body and it serve many function
to human being
FUNCTIONS OF SKIN
1. Protection : Chemicals, particles, Ultraviolet radiation
,Antigens haptens , Microbes
2. Preservation of a balanced internal environment
3. Prevention of loss of water, electrolytes and macromolecules
4. Lubrication and waterproofing
5. Shock absorption : strong, yet elastic and compliant covering.
6. Sensation
7. Calorie reserve
8. Vitamin D synthesis
9. Temperature regulation
10. Psychosocial, sexual : hair, nail,..
SKIN DISEASE IMPACT
The skin diseases impact on the human being is illustrated by the 5 D
SKIN COMPONENT
The skin is composed from three main layers with appendages
The main skin layers are :
Epidermis
Dermis
Subcuataneous fat tissue
The main skin appendages
Hair
Nails
Sweat gland and sebaceous glands
EPIDERMIS
Stratified sqaumous epitheium ( Keratinocytes).
Keratinocytes:85- 95% of Epidermal cells.
4- cell layers: Basal layer , spinous (Prickle ) layer ,Granular layer , horny
layer ( stratum corneum )
Desmosomes: the major adhesion structure between KC. If damaged will
lead to Acantholysis (separation of keratinocytes) .
Hemi-desmosomes : connect basal keratinocytes to the underlying
basement membrane .
EPIDERMIS-CELLS OTHER THAN KC
Melanocytes :melanogenesis ( melanin synthesis ) , dendritic .
Langerhans’ cells: Bone marrow - derived, APC (antigen presenting cells )
and immune surveillance, Dendritic .
Merkel cells: basal layer, transducers for fine touch, non- Dendritic .
DERMIS
Components: Ground Substance, Fibres (most imp collagen ), Cells and other
structures.
Makes about 15-20% of human body weight
thickness: 1mm eyelids , 5mm back
Interdigitates with Epidermis via dermal papilla
APPROACH TO PATIENTS WITH
DERMATOLOGICAL DISEASE
History
Examination
Dermatological investigations
Other investigations
HISTORY
Hx of skin lesions/rashes (dermatological hx ):
When did it start (duration .. Acute vx chronic )
Where did it start (site)
How did it spread ( for ex : trunk to limbs, limbs to trunk…)
Evolution :improving , same , worse .
Symptoms: itch, pain
Provocative factors , exacerbating and relieving factors
Previous treatment/s
HISTORY
Others … hx as in medicine :
Review of systems: brief for relevant systems (ex : joints , eyes …. )
Past medical history
Drug history and allergies.
Family medical history and history of skin diseases (ex FH of psoriasis or atopy )
Social history ( animal contact, smoking , travel hx ...)
Sexual history
EXAMINATION
Type/s of lesions
Shape of lesions
Arrangement
Distribution
EXAMINATION (T).
primary lesions :
Macule/patch: flat ( not elevated ) , alteration of colour or texture
Papule/plaque: raised (elevated) areas without depth
Nodule: solid mass in the skin with significant depth (induration)
Vesicle/bullae/blister: fluid filled spaces.
Pustule/abscess: pus accumulation ( apoptotic cells , debris , and Neutrophils)
Wheal: elevated , white , compressible and evanescent (transient )
Comedon: greasy plug of keratin in pilosebaceous orifice
Petechiae: pin point bleeding (platelet problem)
Ecchymosis: large bleeding
hematoma: bleeding collection , leading to swelling of skin.
(T)
Secondary lesions (modified):
Scale : flakes of horney layer ( represents hyperproliferation of epidermis)
Crust : dried blood or pus or serum (represent damage to skin)
Lichenification : thickened skin with increased markings (represents repeated
scratching )
Burrow : gray whitr toutous line (up to 1 cm) , seen in scabies
Erosion: loss of epidermis only. Heals without scarring.
Ulcer: loss of epidermis and at least part of dermis. Heals with scar formation.
SHAPE (S)
Shape of lesion/s:
Colour
Surface:
Scaly: papulosquamous disorders
Non scaly: erythemas ( purpuras vs reactive erythemas , to differentiate
between them use diascopy)
Margin :
Well defined: psoriasis
Ill defined :Eczema
ARRANGEMENT(A)
*Linear: epidermal naevi, kobner phenomenon .…
*Grouped: Herpes simplex
*Annular (ring-like): fungal infection (tinea)
* nummular ( coin-like ) : in discoid eczem
* dermatomal : with hepes zoster (shingles)
DISTRIBUTION(D)
*affected site , ex :
-Localized: unilateral , acral, sun exposed area , ….
- Generalized.
ALSO IN EXAMINATION
*Good light source
*Examine all skin surface
*Don’t forget examening hair , nail , mucosa , palmoplantar surfaces , genitalia (if
needed) .
SKIN DISEASE CAN BE PART OF SYSTEMIC
DISEASE …
Ex . Patient with butterfly rash on face , arthralgia , oral ulcers … can be SLE .
Ex2 patient with mouth abd genial ulcers , uveitis … can be becet disease
Ex3 pt with erythema nodosum , abdominal pain , chronic diarrhea … can be IBD .
DERMATOLOGICAL INVESTIGATION TOOLS
Wood’s light: infections, pigmentary problems.
KOH .
Diascopy
Tzanc smear
Patch test
Skin biopsy and immunofluorescence.
OTHERVINVESTIGATIONS
Depending on individual cases :FBC,LFT,KFT,CXR….. .
PAPULES AND PLAQUES
LINEAR EPIDERMAL NAVEUS
ANNULAR
GROUPING
DERMATOMAL
MARGINS WELL-DEFINED
PSORIASIS
SCALY WELL DEFINED MARGINS.
ECZEMA ..ILL DEFINED BORDER
MACULES AND PATCHES
BULLAE
WHEAL
ULCER
FUNGAL HYPHAE
TZANC SMEAR
IMMU FLUO.
The end