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Dermatology
1.
2. Contents
Elements of the skin rash.
4
What’s the skin?
1
What does it do?
2
What’s made of?
3
Dermatopathology.
5
3. • The skin is the largest organ of the body, which
covers the entire surface.
• Total area is about 15-20 square feet with thickness
of 0,3 to 3 mm. Accounts for 7% of body weight. (it
weights twice as much as your brain)
What’s the skin?
1
4.
5. • Protects: mechanical, chemical, bacterial
• Body temperature regulation
• Prevent water loss
• Metabolic: synthesize vitamin D
• Cutaneous sensation
• Excretion and secretion
• Prevent UV damage
• Storage of fat and blood
• Absorbtion
What does it do?
2
7. 1. The epidermis
• Is a thin layer of skin, made up of keratinized
stratified squamous epithelium
• It is the most superficial layer of skin, the layer you
see with your eyes when you look at the skin
anywhere on your body
• Varies in thickness from a few cells (eyelids) to
dozens of cells thick (palms and soles of feet)
8.
9. 1. The epidermis
• This epidermis layer is further divided into five,
separate layers.
• In order from most superficial to
deepest, they are the:
⦿ Stratum Corneum
⦿ Stratum Lucidum
⦿ Stratum Granulosum
⦿ Stratum Spinosum
⦿ Stratum Basale
10. STRATUM BASALE
• is a single layer of cells primarily
made of basal cells. A basal cell is a cuboidal-
shapedstem cell that is a precursor of the keratinocytes
of the epidermis
• All of the keratinocytes are produced from
this single layer of cells, which are constantly going
through mitosis to produce new cells
• Two other cell types are first is Merkel cell, which
functions as a receptor and is responsible for
stimulating sensory nerves that the brain perceives as
touch. These cells are especially abundant on the
surfaces of the hands and feet. The second is
a melanocyte, that produces the pigment melanin
11. STRATUM BASALE
• Two other cell types are first is Merkel cell, which
functions as a receptor and is responsible for
stimulating sensory nerves that the brain perceives
as touch. These cells are especially abundant on
the surfaces of the hands and feet
• The second is a melanocyte, that produces the
pigment melanin
13. STRATUM SPINOSUM
• As the name suggests, it is spiny in appearance due to
the protruding cell processes that join the cells via a
structure called a desmosome. The desmosomes
interlock with each other and strengthen the bond
between the cell
• The stratum spinosum is composed of 8 to 10 layers of
keratinocytes, formed as a result of cell division in the
stratum basale . Interspersed among the keratinocytes
of this layer is a type of dendritic cell called the
Langerhans cell, which functions as a macrophage by
engulfing bacteria, foreign particles, and damaged cells
that occur in this layer
16. STRATUM SPINOSUM
• The keratinocytes in the stratum spinosum begin
the synthesis of keratin and release a aterrepelling
glycolipid that helps prevent water loss from the
body, making the skin relatively waterproof.
• As new keratinocytes are produced and
pushed into the stratum granulosum.
17. STRATUM GRANULOSUM
• it has a grainy appearance due to further changes to
the keratinocytes. The cells become flatter, cell
membranes thicken, and they generate large amounts
of the proteins keratin, which is fibrous, and
keratohyalin, which accumulates as lamellar granules
within the cells
• The nuclei and other cell organelles disintegrate as the
cells die, leaving behind the keratin, keratohyalin, and
cell membranes that will form the stratum lucidum, the
stratum corneum, and the accessory structures of hair
and nails. This is the layer where part of keratin
production occurs
19. STRATUM LUCIDUM
• This layer is found only on palms of hands,
fingertips, and soles of feet. These are packed
with eleiden, a clear protein rich in lipids, derived
from keratohyalin, which gives these cells their
transparent (lucid) appearance and make
waterproof
20. STRATUM CORNEUM
• This is thickest layer, composed by elongated,
mature Keratinocytes or dead skin cells that you
shed into the environment—the entire epidermal
layer is replaced every four weeks. In fact, it is
estimated that an individual will shed about one
pound of skin every year throughout your home
21.
22. 2. The dermis
• Underneath the epidermis lies the dermis
• It might be considered the “core” of the
integumentary system, It contains blood and lymph
vessels, nerves, mast cells and other structures,
such as hair follicles and sweat glands
• It is made of two layers of connective tissue that
compose an interconnected mesh of elastin and
collagenous fibers, produced by fibroblasts
23.
24. Papillary Layer
• It is also known as upper dermis, made of
loose, areolar connective tissue, which
means the collagen and elastin fibers of this
layer form a loose mesh
• This layer of the dermis projects into the
stratum basale of the epidermis to form
finger-like dermal papillae
25. Reticular Layer
• Underlying the papillary layer is much
thicker reticular layer, also known as lower dermis
and composed of dense, irregular connective
tissue.
• This layer is well vascularized and has a rich
sensory and sympathetic nerve supply. The
reticular layer appears reticulated (net-like) due to
a tight meshwork of fibers
27. Nails
• The nail plate is the permanent product of the nail
matrix. Its normal appearance and growth depend
on the integrity of several components such as the
tissues surrounding the nail, or perionychium, the
bony phalanx that contribute to the nail apparatus
or nail unit
28. Hair follicles
• Invaginations of the epidermis into the deep dermis,
forming a cavity where the hair grows and develops.
• Function: contraction, which is responsible for
piloerection (goosebumps)
Hair
Composition
Hair shaft
Extends above
the epidermis
Hair bulb
Root of the
hair follicle;
located deep in
the dermal
papilla
Receives blood
and nutrients
from a capillary
network of
vessels to sustain
hair growth
Arrector
pili
muscle
Obliquely directed
smooth muscle
fibers that attach to
the dermal sheath
surrounding hair
follicles
29. Types of hairs
Vellus hair follicle
• Extends into the
reticular dermis
• Found throughout the
body
• During puberty, vellus
hairs in the axillae and
the genital area
become terminal hairs
Terminal hair follicle
• Extends into
subcutaneous fat
• Found on the scalp,
eyebrows, and
eyelashes
31. Sebaceous glands
• Description:
Exocrine (holocrine) branched glands
• Location and distribution:
Dermis, predominantly located on the face and scalp, absent
on palms and soles
• Function
Secretion of sebum (an oily, waxy substance which is a
lubricant and a waterproof layer for the skin and hair; has
photoprotective, antimicrobial, and antioxidant properties)
• Regulation of secretion
Stimulated by androgens, especially dihydrotestosterone
Inhibited by estrogens
33. Sweat glands
Eccrine sweat glands
• Exocrine glands with a spiral duct
(acrosyringium) and secretory ducts
that open into sweat pores
Most areas of the body
Absent in lips, ear canal, clitoris,
labia minora, and glans penis
Apocrine sweat glands
• Exocrine glands with a secretory unit
(glomerulum) and excretory ducts
that open into hair follicles
Mostly axilla, perineum, areola of the
nipple, and external ear
• Composed of a secretory unit called glomerulum or acrosyringium; surrounded
by myoepithelial cells
• The combination of sebaceous gland, arrector pili muscle, and hair follicle is
known as the pilosebaceous unit.
34. Sweat glands: Function and Regulation
Eccrine sweat glands
• Secretion of sweat
(thermoregulation)
Stimulated by acetylcholine via
muscarinic receptors
Apocrine sweat glands
• Modified apocrine cells produce ear
wax or breast milk.
• No significant role in
thermoregulation
Stimulated by epinephrine and
norepinephrine from adrenergic
nerve fibers
Circulating hormones may also affect the secretion of sweat:
Growth hormone: ↑ size of sweat glands
Thyroid hormone: ↑ secretion of sweat (i.e., hyperthyroidism is
characterized by moist and warm skin)
36. • The deepest layer of the skin, composed by well
vascularized, loose, areolar connective tissue and adipose
tissue
• That functions as a mode of fat storage and provides
insulation and cushion against physical trauma to internal
organs, muscles, and bones is called the subcutaneous layer
• It contains blood vessels, macrophage, fibroblast and
nerves
• Additionally, the body will turn to this fat in times of
starvation to provide power to its various processes,
especially brain function
37. • Skin lesions may be primary or secondary
Elements of the skin rash.
4
38. Primary lesions
• appear as a direct result of a
disease process
1. Macule
2. Papule
3. Nodule
4. Vesicle
5. Bulla
6. Wheal
7. Pustule
8. Tuberculum
Secondary lesions
• may develop from primary
lesions or result from external
trauma
1. Scale
2. Crust
3. Fissure
4. Ulcer
5. Erosion
6. Excoriation
7. lichenification
8. Vegetation
9. Scar
10. Secondary spot
41. Primary skin lesions: Macule
• A flat (nonpalpable) skin lesion vary in size that
differs in color from surrounding skin (e.g., freckle;
also seen in pityriasis versicolor, nevus spilus)
44. Primary skin lesions: Papule
• A small, palpable skin lesion ≤ 1 cm in diameter
(e.g., seen in lichen planus, molluscum
contagiosum, neurofibromatosis type 1, acne)
51. Primary skin lesions: Vesicle
• Small fluid-containing blister (collection of fluid in
the skin) ≤ 1 cm in diameter (e.g., seen in eczema
herpeticum, chickenpox, herpes zoster)
59. Primary skin lesions: Wheal
• Well-circumscribed, pruritic, and erythematous
papule or plaque with dermal edema and irregular
borders (e.g., seen in urticaria)
• Transient (hours to days)
65. Primary skin lesions: Tuberculum
• formations that do not have a cavity, they lie in the
dermis and vary in size from 5 to 10 mm in
diameter. The skin surface above the tubercle has a
specific color and relief, and after healing, a scar or
an area of skin thinning is formed. If left untreated,
the tubercle may turn into other morphological
elements of the rash, up to ulcers.
• The tubercles are observed in Leprosy, tuberculosis
of the skin, leishmaniasis, tertiary syphilis, etc.
69. Primary lesions
• appear as a direct result of a
disease process
1. Macule
2. Papule
3. Nodule
4. Vesicle
5. Bulla
6. Wheal
7. Pustule
8. Tuberculum
Secondary lesions
• may develop from primary
lesions or result from external
trauma
1. Scale
2. Crust
3. Fissure
4. Ulcer
5. Erosion
6. Excoriation
7. lichenification
8. Vegetation
9. Scar
10. Secondary spot
70. Secondary skin lesions: Secondary
spot
• PIGMENTATION DEPIGMENTATION (PD) - this is a
result of the accumulation or disappearance of the
pigment (melanin), PD may be also as the result of
haemosiderin deposition in the skin when blood
vessels was damaged.
• PD can be formed in place of any
morphological element.
88. Secondary skin lesions:
Excoriation (scratch marks)
• Abrasion produced by mechanical force, usually
involving the epidermis (but may reach the outer
layer of the dermis)
92. Secondary skin lesions: Scar
• Composed of new connective tissue that has
replaced lost substance
• An overgrowth of scar tissue manifests as a keloid
(thickened, raised tissue that grows beyond the
borders of the scar and shows no regression).
96. Secondary skin lesions:
lichenification
• An area of rough, thickened epidermis inducted by
rubbing or scratching, the skin lines are
accentuated so that the surface looks like a wash
board (eg, chronic eczema and lichen simplex)
99. Secondary skin lesions: Vegetation
• is soft growing (proliferation), resembling to cocks
combs or cauliflower. Vegetation is the result of the
proliferation of papilla dermis with thickening
spongious layer (between-nipple epidermal
outgrowths).
• Vegetation are formed on the surface of erosions
and papules, especially located in areas of high
friction, sweating, prone to trauma.
• Vegetation may be primary - sharp-point
condyloms
103. Dermatopathology
5
Histopathologic
finding
Characteristics Examples of associated
conditions
Acantholysis Separation of epidermal cells due to
dissolution of intercellular bridges of the
stratum spinosum (e.g., desmosomes)
Pemphigus vulgaris
Acanthosis Epidermal hyperplasia of the stratum
spinosum
Acanthosis nigricans
Psoriasis
Vacuole
dystrophy
Intracellular edema of keratinocytes
with formation of vacuoles in the
cytoplasm of the stratum spinosum and
granulosum
Systemic lupus
erythematosus
Herpes sipmlex
Balloon
dystrophy
Sharply expressed edema of the
epidermis, having both intercellular and
intracellular character
Herpes simplex
Herpes zoster
104. Dermatopathology.
5
Histopathologic
finding
Characteristics Examples of associated
conditions
Hypergranulosis Thickening of the stratum granulosum Lichen planus
Hyperkeratosis Thickening of the stratum corneum Psoriasis
Calluses
Parakeratosis Retention of nuclei in the stratum
corneum
Psoriasis
Actinic keratosis
Spongiosis Intraepidermal and intercellular edema Eczematous dermatitis
Dyskeratosis Premature keratinization of the stratum
granulosum
Squamous cell carcinoma
Papillomatosis The projection of dermal papillae above
the surface of the skin, resulting in an
irregular undulating configuration of the
epidermis
Often combined with
acanthosis
