Introduction to Dermatology

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Introduction to Dermatology

• By
• Stacey Singer-Leshinsky R-PAC

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What is?

• Dermatology?
• Dermatologist?

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Functions of the Skin

• Sensation-
• Immune function-
• Thermoregulation-
• Cutaneous absorption

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Functions of the Skin

• Excretion
• Vitamin D synthesis-
• UV light for 10-15 minutes.

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Skin AnatomyLayers

• Epidermis- outermost, no blood vessels or blood
  supply.
• Dermis- vascular layer/sensation. Strength and
  elasticity to skin.
• Hypodermis or subcutaneous layer.

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Skin AnatomyEpidermis-5 Layers

• Stratum corneum-
• Stratum lucidum-
• palms and soles of feet only.

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Skin AnatomyEpidermis-5 Layers

• Stratum granulosum-
• Most differentiated layer.

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Skin AnatomyEpidermis-5 Layers

• Stratum spinosum-
• Has desmosomes (spiny projections and so
  spinosum).

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Skin AnatomyEpidermis-5 Layers californians like
girls in string bikinis)

• Stratum basale-
• deepest layer of the epidermis.
• Consists of a single layer of keratinocytes.

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Skin AnatomyEpidermis-Cell Types

• Melanocytes-
• Produce melanin. Not many melanocytes in soles
  or palms.
• Albinos lack tyrosinase
• Cancer of a melanocyte known as melanoma

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Skin AnatomyEpidermis-Cell Types

• Keratinocytes
• Produce keratin
• Immunology role-
• Protection and water proofing
• Merkels cells- Free nerve endings attached to
  epidermal cells.

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Skin AnatomyEpidermis-Cell Types

• Langerhans cells
• Found in epidermal layers with keratinocytes
• Involved in cell-mediated hypersensitivity,
  antigen processing and recognition, stimulation
  of immune competent cells and graft rejection.

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Skin AnatomyEpidermis-Cell Types

• Parakeratosis-Retention of nuclei in stratum
  corneum.
• Spongiosis-Intercellular edema of the epidermis.
  

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Skin AnatomyBasement membrane(Basal lamina)

• Selectively filters molecules moving between two
  layers.
• Immunoglobulin and complement deposition in skin
  disease.

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Skin AnatomyDermis

• Thickest skin layer/connective tissue layer.
• Composed of collagen, blood vessels, nerves, hair
  follicles, and sweat glands

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Skin AnatomySubcutaneous Tissue

• Eccrine glands and deep hair follicles extend to
  this layer
• Insulator/shock absorber/stores energy as
  calories

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Skin AnatomyAppendages-Hair

• Hair follicle associated with sebaceous gland to
  form pilosebaceous unit.
• Growth is cyclic
• Anagen phase-
• Catagen-
• Telogen phase-

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Skin AnatomyAppendages-Hair

• Hair loss due to

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Skin AnatomyAppendages-Nails

• Hardened keratinized plates

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Skin AnatomyAppendages-Glands

• Sebaceous- Entire skin surface except palms,
  soles, sides of feet. Secrete sebum

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Skin AnatomyAppendages-Glands

• Sweat glands-
• Eccrine-Originate in dermis and open on skin
  surface.
• Apocrine- Large, deep in dermal layer. Open
  through a hair follicle. Mostly in axillae and
  groin.

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Common Skin LesionsEqual to plane of the Skin

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Common Skin LesionsEqual to plane of the Skin
Telangiectasia-
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Common Skin LesionsEqual to plane of the Skin
Petechiae-
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Common Skin LesionsEqual to plane of the Skin
Purpura or ecchymosis
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Common Skin LesionsEqual to plane of the Skin
Sclerosis
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Common Skin LesionsEqual to plane of the Skin
Lichenification
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Common Skin LesionsEqual to plane of the Skin
Acanthosis
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Common Skin LesionsAbove the plane of the Skin
Actinic Keratosis
Hyperkeratosis
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Common Skin LesionsAbove the plane of the Skin.
Corn
Callus
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Common Skin LesionsAbove the plane of the Skin

papule
Nodule
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Common Skin LesionsAbove the plane of the Skin
Wheal
Plaque
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Common Skin LesionsAbove the plane of the Skin

• Vesicle-
• Blister-
• Bulla-

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Common Skin LesionsAbove the plane of the Skin
Pustule- Cyst-
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Common Skin LesionsAbove the plane of the Skin
Tumor
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Common Skin LesionsAbove the plane of the Skin
Verruca
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Common Skin LesionsAbove the plane of the Skin

Scale/crust Desquamation
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Common Skin LesionsAbove the plane of the Skin

Exudate
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Common Skin LesionsAbove the plane of the Skin

Comedone
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Common Skin LesionsBelow the plane of the Skin

Excoriation
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Common Skin LesionsBelow the plane of the Skin
Ulcer
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Common Skin LesionsBelow the plane of the Skin
Fissure
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Common Skin LesionsBelow the plane of the Skin
Excoriation
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Common Skin LesionsBelow the plane of the Skin
Eschar
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Disorders of Pigmentation and Melanocytes
Blanched

• Vitiligo

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Disorders of Pigmentation and Melanocytes

• Albinism

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Disorders of Pigmentation and Melanocytes

• Melasma

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Disorders of Pigmentation and Melanocytes

• Lentigo-
• Due to melanocyte proliferation.
• Can be due to hypermelanosis, Addisons disease,
  Hemochromatosis, Acanthosis nigricans
• Hydroquinone may temporarily bleach the spots
  Inhibit synthesis of pigment

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Common Skin LesionsBased on Color- Erythema
Erythema
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Common Skin LesionsBased on Color- Blue

• Cyanosis

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Common Skin LesionsBased on Color- yellow

• Jaundice

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Approach to patient

• Distinguish normal vs. abnormal
• Appropriate differential diagnosis
• Pros and Cons of dermatology
•  

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Approach to the PatientHistory-Lesions

• Acute vs. chronic illness
• Onset
• Subjective symptoms
• Location, distribution, spread or change in
  lesions

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Approach to PatientPhysical Exam

• Observe four points
• Palpate
• Systemic examination including lymphadenopathy,
  organomegaly, arthralgia, and neurological changes

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Approach to PatientPhysical Exam

• Rash-
• Lesion-

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Physical ExamShape of the Lesion

• Round
• Oval
• Polygonal
• Annular
• Serpiginous
• Umbilicated

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Physical ExamArrangement of lesions

• Grouped herpetiform, arciform, annulra,
  reticulated, linear,

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Physical ExamArrangement of lesions
Disseminated-
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Physical ExamArrangement of lesions
Demarcated Discrete
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Physical ExamArrangement of lesions
Diffuse-
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Physical ExamDistribution of lesions

• Extent
• Pattern
• Any characteristic patterns such as seen in acne,
  chicken pox.

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Special Signs and tests Darier sign

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Special Signs and tests Auspitz Sign

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Special Signs and tests Nikolsky sign

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Special Signs and tests Diascopy

• Diascopy-
• Blanching indicates intact capillaries known as
  erythema.
• If no blanching capillaries are not intact, known
  as purpura.

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Special Signs and tests Koebner phenomenon

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Diagnostic TechniquesWood Light Exam
Hair green fluorescence in tinea capitis Skin
erythrasma coral red fluorescence Hypomelanosis
decrease in intensity
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Diagnostic TechniquesAcetowhitening
Acetowhitening-
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Diagnostic Techniques Patch test

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Diagnostic TechniquesMicroscopic Examination

• KOH preparation
• For bacteria gram stain
• For virus Tzanck smear
• For spirochetes
• Cultures bacterial, viral, parasitic, mycologic

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Diagnostic techniquesBiopsy

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Review 1

• Name the five layers of the epidermis
• What enzyme is lacking in albinos? What does this
  enzyme produce?
• Which cells are known as touch receptors?
• What is the function of the basement membrane?
• Which layer is composed of fat, connective tissue
  and blood vessels?

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Review 2

• List two types of sweat glands and state their
  difference.
• Describe a macule
• What is Telangiectasia?
• Describe lichenification
• Describe a papule
• Describe a nodule

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Review 3Describe this
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Review 4What is this?
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Review 5What is this?
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Review 6What is this due to?
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Review 7What is this?
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Review 8What is this?
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Review 9

• How would you describe this lesion?
• What is the diagnosis?

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Review 10

• Describe this lesion
• What is your diagnosis?

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Review 11

• What is this?

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Review 12

• How would you describe these lesions?

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Review 13

• How would you describe this lesion?

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Review 14

• What is this sign? What does it mean?

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Review 15

• Filled with pus this is known as
• Filled with fluid this is known as
• If this is embedded in the skin and filled with
  fluid it is known as
• If it is solid it is known as

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Review 16

• what sign is positive?

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Review 17

• What sign is positive?

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Review 18

• How would you define these markings?