Transcript Lecture 1. Anatomy, histology, physiology of the skin. Methods of

Anatomy, histology, physiology of the skin.
Methods of examination of patients with skin
diseases. Morphology of primary and secondary
skin lesions.
Lector: Shkilna M.
Content
Anatomy of skin:
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Epidermis
Dermis
Subcutis
Skin appendages .
Functions of the skin.
Methods of examination of patients with skin diseases:
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Patient’s passport.
Patient’s complaints.
History of present illness.
Life history (past history).
Objective investigation (morphology of primary and secondary skin lesions).
Investigations.
SKIN… the heaviest single organ of
the body!
Skin is the largest organ of the body, it constitutes about 16% of body weight.
Anatomy of skin
Epidermis
Dermis
Hypodermis or
subcutaneous tissue
Appendages (hair,
nails, sebaceous and
sweat glands).
Pic: Epidermal Layers
Dermis is organized into two
distinct areas:
Papillary dermis (the superficial zone).
Reticular dermis
(the deeper zone - it composes the bulk of the dermis).
Components of the dermis:
collagen (70-80%) –
for resiliency;
elastin (1-3%) –
for elasticity;
proteoglycans –
to maintain water within the dermis.
Subcutis or subcutaneous fat :
is arranged into distinct
fat lobules which are
divided by fibrous
septae blood vessels,
nerves, and lymphatics
are also found in the
fibrous septae.
Skin vessels:
Superficial net
(in granular cell
layer).
Deep plexus
(in subcutaneous
fat).
Skin nerves:
Appendages
Eccrine sweat glands (open
directly onto surface of skin
and regulate body temp)
Apocrine glands (axillae,
nipples, areolae, anogenital
area, eyelids and external
ears) respond to emotional
stimuli, bacteria causes body
odor.
Sebaceous glands (secrete
sebum, keep skin/hair from
drying out) stimulated by
hormones
Hair (Vellus and Terminal)
Nails (protect distal ends of
fingers/toes)
Functions of the skin:
Barrier.
Metabolic.
Temperature regulation.
Secretion.
Immune surveillance.
Coetaneous sensation.
Methods of examination of patients
with skin diseases
1. Patient’s passport.
2. Patient’s complaints:
a) skin rashes
b) subjective sensation, which are connected with
skin rashes:
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itch of the skin;
burning;
pain;
skin weeping;
dryness of the skin;
feeling of a tense skin;
weakness, weight loss, fever etc.
History of present illness:
Possible etiology of the disease
( according patient’s mind).
Duration of the disease:
Acute ( < 2 month)
Chronic ( > 2 month).
Course of a disease.
Previous treatment and effect from it.
Family history:
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contagious diseases;
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hereditary diseases.
Life history (past history):
 Past medical history.
 Associated inner diseases.
 Occupational hazards.
 Allergic history.
 Harmful habit.
Objective investigation
 General state of the patient
( satisfactory or not, fever etc. ).
 Systems revive.
 Assessment of nails, hair, and
mucosal surfaces, even if these
are recorded as unaffected.
Objective investigation (continued)
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Palpation ( to diagnose):
Skin elastic.
Skin moistness.
Subcutaneous fat.
Lymphatic nodes: ( size, consistency,
movable or immovable etc.).
Dermatological status:
 Inspection.
 Palpation.
 Scraping.
 Dermoscopy.
 Laboratory end special methods.
Inspection:
Skin texture
Lesions:
 type: primary and secondary;
 color: red, brawn, white;
 shape: round, oval, annular;
 arrangement: grouped (herpetiform,
zoster form), disseminated
(erythrodermic psoriasis).
Examination of Lesions
Configuration
Annular (rings)
Grouped
Linear
Diffuse
DISTRIBUTION
CONFIGURATION
Morphology of primary and
secondary skin lesions
Primary skin lesions
is the initial lesion that has not been altered by
trauma, manipulation (scratching, scrubbing),
or natural regression over time.
Types:
primary lesions without cavity;
primary lesions with cavity.
Primary lesions without cavity:
Macula's
Urtica
Papule
Nodule
Macula and Patch
Description
Circumscribed
Flat
Discoloration
Smaller than 0.5 cm-macula
Larger that 0.5 cm- patch
May be brown, blue, red.
MACULE
Description
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Circumscribed
Flat
Discoloration
Smaller than 0.5 cmmacule
 Larger that 0.5 cm- patch
 May be brown, blue, red or
hypo pigmented
 Inflammatory
 Noninflammatory
TINEA VERSICOLOR
BROWN MACULE
Becker's nevus.
This lesion contains
no pigmentation.
Becker's nevus.
A typical lesion with
macular pigmentation
and hair.
PAPULE
Description
– an elevated solid lesion
up to 0.5 cm in diameter
– Color varies: flesh,
yellow , white, brown,
red, blue or violet
– May become confluent
– May form plaques
PLAQUE
Description
A circumscribed,
elevated, superficial,
solid lesion more than
0.5cm in diameter
often formed by
the confluence of
papules
Plaque
PSORIASIS PLAQUE
SECONDARY SYPHYLIS
Examples of Plaques
 Eczema
 Pityriasis roseas
 Tinea corporis
 Psoriasis
 Syphilis
Nodule
Description
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Circumscribed
Often round
Solid lesion
More that 0.5 cm in
diameter
– Larger nodule is a
tumor
Metastatic carcinoma of the breast.
LIPOMA
BENIGN TUMOR
WHEAL (HIVE)

Description
Starts as red erythematous macules.
Soon paleoedematous wheals develop
Irregular, asymmetrical
Velvety to touch
Erythematic well defined, fades on
pressure
Subside within few hours without
leaving any trace
Dermographism positive
Wheals develop along line of
scratching or pressure.
Physical urticaria
Cold urticaria : Reaction to cold, such as ice, cold air or
water - worse with sudden change in temperature
Primary lesions with cavity:
Vesicles
Bulla
Pustules
Cyst
Vesicle
Description
 Circumscribed
collection of free
fluid
 Up to 0.5 cm in
diameter
Herpes zoster
Bulla formed due to fluid in the skin and fluid
collection occurs at sites where the cohesion on the skin
is weak:
Subcorneal
Intra – epidermal, due to
individual keratinocytes
Dermo – epidermal
junction
A circumscribed collection
of free fluid more than
0,5 sm in diameter
PUSTULE
Description
 Circumscribed
collection of
leukocytes
 Free fluid
 Varies in size
Staphylococcal folliculitis
CYST
A circumscribed
lesion with a wall
and a lumen, it
may contain fluid
or solid matter
Secondary skin lesions
Types:
Scale.
Crusts.
Erosions.
EROSION
Description
 A focal loss of
epidermis;
 erosions do not
penetrate
below the
dermoepidermal
junction;
 and therefore heal
without scarring
Toxic epidermal necrolysis
CRUST
Impetigo.
A thick, honey-yellow adherent crust covers the
entire eroded surface.
Description
Is a collection of dried serum and cellular debris- a scab
Examples
– Acute eczematous inflammation, Atopic on the face, Impetigo- golden
or honey colored, Tinea capitis.
Ulcer
A focal loss of
epidermis and dermis,
and heal with scarring
Examples
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Decubitus
Ischemic
Stasis ulcers
Neoplasm's
FISSURE
Description
A linear loss of epidermis
and dermis with sharply
defined nearly vertical
walls
Examples
– Chapping – hands and
feet
– Eczema on the finger
tip
Asteatotic eczema.
Excessive washing produced this
advanced case with cracking and fissures.
ATROPHY
Description
A depression in
the skin
resulting from
thinning
of the epidermis
or dermis
Lichen sclerosus et atrophicus.
The epidermis is thin and atrophic and gives the
appearance of wrinkled tissue paper when
compressed.
Scar
Description
An abnormal formation of
connective tissue, implying
dermal damage, after injury
Are initially thick and pink, but
become white and atrophic
Examples
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Post surg.
Burns
Keloid
Post any herpes
Keloids on the chest and extremities are
raised with a flat surface.
The base is wider than the top.
EXCORIATION
An erosion
caused by
scratching;
excoriations
are often
linear.
LICHENIFICATION
Description
An area of thickened
epidermis induced by
scratching
Skin lines are accentuated
so it looks like a
washboard
Examples
– Atopic dermatitis,
chronic eczematous
dermatitis
LICHENIFICATION
Scales
Description
Excess dead epidermal
cells that are produced by
abnormal keratinization
and shedding.
The may be
fine, as in pityriasis;
white and silvery, as in
psoriasis;
or large and fish-like, as
in ichthyosis
Dominant ichthyosis vulgaris
INVESTIGATIONS
General laboratory investigation:
General blood analysis.
General urine analysis.
Stool test for parasites.
Examination of blood for sugar.
Wasserman reaction.
INVESTIGATIONS
Diagnostic Tests
Skin Biopsy
Culture and sensitivity (viral, bacteria, fungi)
Immunofluorescence
Allergy Tests
 Skin Scrapings
Tzanck Smear
Wood’s Light Examination
Clinical Photographs
Diascopy
EPILUMINESCENCE MICROSCOPY
(DERMATOSCOPY, DERMOSCOPY)
This refers to surface
microscopy using an
illuminated lens with oil
immersion directly on to the
skin's surface. The presence
of oil reduces specular
reflection and reduces
'errors' due to the different
refractive indexes of the
various superficial layers of
skin.
SCRAPING
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Hidden scaling of the
skin.
Psoriatic phenomenonts.
Purpura symptom.
Step A: Gently scrape the lesion with a glass
slide. This
accentuates the silvery scales (Grattage test
positive).
Scrape off all the scales.
Step B: As you continue to scrape the lesion, a
glistening
white, adherent membrane appears.
Step C: On removing the membrane, punctate
bleeding
points become visible.
DIASCOPY
A glass slide is pressed firmly on
the skin lesion. If a red lesion
blanches, it implies that the red
colour is secondary to blood
within the vessels. By contrast,
blood outside the vessels, such as
that from a bruise or from
vasculitis, will not blanch.
Success in blanching is a more
useful physical sign than failure to
blanch.
Granulomatous lesions a glass
slide reveals an appearance
commonly referred to as 'apple
jelly nodule'.
Inflammatory or
no inflammatory types of
lesions
WOOD'S LIGHT
This involves irradiation with a UV
light source that causes normal skin,
particularly dermis, to fluoresce (in
the visible light range).
The basis for this is that in the
ultraviolet A wavebands used by
Wood's light, pigmentation has a
greater degree of absorption than at
longer wavebands, resulting in a
greater degree of difference in
fluorescence between pigmented and
depigmented skin.
Wood's light also enhances the
examination of cutaneous pigmentary
abnormalities such as in patients with
vitiligo, where areas of subtle
depigmentation are more easily seen.
MYCOLOGY SAMPLES
Coetaneous scale, nail clippings and plucked hairs can be
examined by light microscopy when mounted in 20%
potassium hydroxide.
The keratin is dissolved, allowing fungal hyphae to be
identified.
SWABS
Bacterial swabs in an appropriate culture medium are sometimes
useful.
PRICK TESTS
Prick tests are a way of detecting coetaneous type I (immediate)
hypersensitivity to various antigens such as pollen, house dust mite or dander.
The skin is pricked with a dilution of the appropriate antigen solution. After
10 minutes a positive response is indicated by a weal and a flare. The weal is
due to a local increase in capillary permeability and the flare a result of
activation of the axon reflex.
IMMUNOFLUORESCENCE
A portion of the skin biopsy can be frozen in liquid
nitrogen for direct immunofluorescence (IF). This
involves visualising antigens that are present in skin
by identifying them with fluorescein-labelled
antibodies. Similarly, indirect immunofluorescence
can identify circulating antibodies in the serum by an
additional step of adding the serum to a section of
normal skin or other substrate. Immunofluorescence
plays a major role in the diagnosis of the autoimmune
bullous disorders.
ELECTRON MICROSCOPY
This investigation has played an important role in the
diagnosis of some of the rare blistering disorders such as
epidermolysis bullosa, although the availability of a range
of antibodies to basement membrane zone antigens has in
part replaced it.
PHOTOTESTING
Phototesting involves exposing skin (often on the back) to a
graded series of doses of ultraviolet radiation (UVR) of
known wavelength, either on one occasion or repeatedly.
Laboratory and special methods
General laboratory investigation:
general blood analysis;
general urine analysis;
stool test for parasites;
examination of blood for sugar;
Wasserman reaction.
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