Your Skin
J. C. DiGiacomo, M.D., FACS
Department of Surgery
CentraState Medical Center
Integumentary
System
The Largest of Our 11
Organ Systems.
Consists of the skin (i.e.,
the cutaneous
membrane) plus all the
appendages (or
accessory structures) of
the skin including:
– Sweat glands
(sudoriferous glands)
– Sebaceous glands
(oil glands)
– Hair
– Nails
General Functions of the
Integumentary System
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Protection from Mechanical Injury
Physical Protection of Pathogen Entry
Chemical Prevention of Pathogen Entry
Sensation
Thermoregulation
Metabolic functions
Basic Skin
Structure
Skin has 2 Main Layers:
Superficial, Avascular
EPIDERMIS
Deep, Vascular
DERMIS
Contains Blood Vessels
The Epidermis
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Keratinized Stratified
Squamous Epithelium.
Avascular.
4 Distinct Cell Types
Arranged in Distinct
Layers.
Epidermal Cell Types:
1. Keratinocytes
(structure)
2. Melanocytes
(pigment)
3. Merkel cells
(sensation)
4. Langerhans’ cells
(phagocytes - immune
defense)
Yellow Arrow Indicates The
Epidermis of Thick Skin
Keratinocytes
• Most Numerous Epidermal
Cell – Found in All Layers
of the Epidermis.
• Chief Function is
Production of Keratin – A
Tough Fibrous Protein that
Gives Strength and
Protective Ability.
• Tightly Connected to Each
Other by Desmosomes.
– Provides Continuity,
Strength, and Protection.
– Is the Reason Skin Flakes
Off in Sheets rather than
Individual Cells.
Almost All of the Epidermal Cells in
This Slide are Keratinocytes
Keratinocytes
• New Cells Are
Continuously
Made in the
Deepest Layer
Pushing the
Older Cells Up.
• As They Move
Up from the
Deepest Layer,
They Make
Keratin That
Eventually
Dominates
Their Contents.
When they reach the upper layer,
they are scale-like bags of keratin.
Melanocytes
• Spider-shaped
epithelial cells that
synthesize the
pigment melanin.
• Found in the
deepest layer of the
epidermis.
• Melanin is made and
then packaged into
membrane-bound
granules called
melanosomes.
• Granules are
transferred to the
keratinocytes in the
2 deepest layers of
the epidermis.
Arrows indicate 2
melanocytes.
Melanocytes
• Melanin granules
accumulate on
the “sunny side”
of the nucleus of
the
keratinocytes.
• Melanin granules
protect the DNA
within the
nucleus from
being damaged
by the ultraviolet
radiation from
the sun.
Skin Color
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Due to 3 pigments:
Melanin, Carotene, Hemoglobin
Only melanin is made in the
skin.
Polymer of tyrosine amino acids. Its synthesis is
catalyzed by an enzyme called tyrosinase.
Albinos lack this enzyme.
Color Ranges from yellow to reddish brown to black.
All people have the same # of melanocytes,
individual variations in skin color are due to how
much and what type of melanin is made.
Freckles and moles are local accumulations of
melanin.
Dermis
• Strong, flexible fibrous
connective tissue.
• Provides an arena for
immune cells to fight
invaders.
• Projects upward (as
dermal papillae) to
interdigitate and form a
strong connection with
the epidermis.
• Heavily invested with
blood vessels and Aid in
Temperature Regulation
• Also contains multiple
sensory receptors.
Skin Cancer
• Because of its role as our external covering, the skin
takes a tremendous amount of abuse.
• One serious disorder that can result is skin cancer.
• “Uncontrolled cell division and growth”
• There are 3 types of skin cancers:
– Basal cell carcinoma
– Squamous cell carcinoma
– Malignant melanoma
An abnormal cell develops
From abnormal cells, a
cancerous cell develops
Cancerous cells spread,
forming a tumor
Skin Cancer
• Basal cell carcinoma
– 70% of skin cancers
– Least Aggressive
– Usually cured via surgical
removal
– Consists of uncontrolled
growth of cells of the
stratum basale. They’ll
proliferate and invade the
dermis and hypodermis.
– Often occurs on sunexposed areas of face and
neck
Skin Cancer
• Squamous cell carcinoma
– Arises from keratinocytes
of stratum spinosum.
– 25% of cases.
– Good prognosis if caught
and treated early (surgical
excision or radiation).
– Can be fatal if it
metastasizes to the lymph
nodes.
Skin Cancer
• Malignant melanoma
– Least common and most
dangerous.
– Cancer of melanocytes.
– Often arises from a pre-existing
mole.
– ABCD rule for early detection:
Asymmetry (2 sides do not
match)
Border irregularity
Color (multiple)
Diameter (>6mm is bad!)
Precancerous skin lesions
•Actinic keratoses
•Dysplastic melanocytic nevi
Actinic keratoses
10% risk of malignant transformation
Hypertrophic AK’s
Treatment of AK’s
• Liquid nitrogen cryotherapy
• Topical therapies
– 5-FU (Efudex)
– Imiquimod (Aldara)
• Curettage for hypertrophic lesions
Liquid nitrogen
Cryotherapy
Residual hypopigmentation
Blister formation
Topical therapies
Efudex or Aldara
* 3-5 times per week
* 6-8 weeks
Dysplastic nevi
•Precursors for
melanoma
•Markers for
melanoma
Treatment of dysplastic nevi
• Non-melanoma skin cancers
(NMSC)
– Basal cell carcinoma
– Squamous cell carcinoma
– Keratoacanthoma
Risk factors for development of
BCC and SCC
• Fair skin (Fitzpatrick’s types I-III)
– Blue eyes
– Red hair
• Family history
– Genetic syndromes
• Chronic sun exposure
• Old age
• Arsenic, tar
Nodular BCC
• Chronic lesion
• Easy bleeding
• Pearly border
• Surface telangiectasias
• Head and neck, trunk,
Pigmented BCC
• Similar to nodular but
with black discoloration
– Melanin deposits
• Pigmented races
• Face, trunk, and scalp
Superficial BCC
• Erythematous scaly
plaque
• Slow growth
• Asymptomatic
• Trunk, extremities, face
Morpheaform BCC
• Resembles scar
• Asymptomatic and slow
growing
• Ill-defined margins
• Marked subclinical
extension
• BCC is the most
frequent skin cancer
(80%)
– BCC is 4x more frequent
than SCC
• Metastases are rare
(<1% of cases)
– Local destruction of
tissue
Treatment of BCC
• Curettage electrodessication (ED/C)
• Surgical excision
95% Cure Rate
• Traditional
• Mohs surgery
• Radiation therapy
• Topical therapy
– imiquimod
50-75% Cure Rate
Bowen’s disease
• In-situ SCC
• Arsenic, HPV 16,
radiation
Invasive SCC
• Erythematous nodule
• Indurated lesion
• Sun-exposed skin
– Men > women
• Slow growth
Invasive SCC
Keratoacanthoma
• Low grade SCC
• Rapid growth over
weeks
• Trauma, sun exposure,
HPV 11 and 16
• May progress to
invasive SCC
• SCC is locally invasive and
destructive
• Metastases in 1-3% of
cases
– To lymph nodes
– 50-73% survival
– Distant sites (lungs)
– Incurable
• Invasive
squamous cell
carcinoma
• Surgical excision
– Traditional
– Mohs surgery
• Radiation therapy
Risk factors- MM
• Fair skin, red hair, and blue eyes
• Intermittent sun exposure
– Sunburns
– Tanning beds
• Freckles and melanocytic nevi
• Family history of melanoma
Clinical types- MM
Superficial spreading melanoma
Lentigo maligna melanoma
Acral lentiginous melanoma
Nodular melanoma
ABCD of Melanoma
• Asymmetry
• Border irregularity
• Color variegation
• Diameter >6mm
Prognostic features- MM
• Good prognosis
– Breslow < 1mm
• Intermediate prognosis
– Breslow 1-4mm
• Bad prognosis
– Breslow >4mm
Treatment of MM
• Surgical excision
– In situ = 5 mm margin
– Invasive= 1-3 cm depending on Breslow’s depth