Lecture 1: Intro Flashcards
What are the layers of the skin?
- Epidermis
- Basement membrane
- Dermis
- Subcutaneous layer
What are the functions of the skin?
- Protection from UV through melanin
- Resist mechanical shock
- Thermoregulation
- Mediates sensation
- Protects from environment
- Affects social/sexual communication
- immune barrier to pathogenic org.
- assists in Vitamin D synthesis
- Assists in toxin excretion
- Regulates body fluid loss
How much vitamin D synthesis is performed in the skin?
10-15%
What are the categories/terms used to describe skin lesions?
- Size
- Color and descriptive terms
- Primary skin lesions
- Secondary skin lesions
- Special skin lesion
- Arrangement
- Distribution
What are primary skin lesions?
nitial lesions, not altered by trauma, manipulation or natural regression over time
What are secondary skin lesions?
How the lesions looks over time or after manipulation (ie. scratching, picking, leaking, bursting)
Define depigmented skin
- Absent of melanocytes, no melanin therefore no color
How is skin typed?
- Albino
- Caucasian
- Mediterranean
- Hispanic
- Darkly pigmented: african american
What disease causes depigmentation of the skin?
Vitilago
Define hypopigmentation
- Normal number of melanocytes, but Decreased production of Melanin
- Lighter than skin color
Define Hyperpigmented skin
- Normal # of Melanocytes but
Increased production of Melanin - Darker than skin color
What causes hypopigmented skin?
Psoriasis?
Define erythematous skin
redness of skin
Define atrophic skin, in the epidermal and dermal layers
- thinning of skin
- Epidermal - “cigarette paper”wrinkling
- Dermal/Subcutis – Depression in skin
Define lichenified skin lesions
- Focal area of thick skin
- Produced by chronic manipulation
- Accentuated skin lines – “washboard”
Define verrucous skin lesions
Hyperkeratotic or Wart Like
Define Umbilicated skin lesions
Central “belly button” like depression
What terms are used to describe primary skin lesions?
MACULE - PATCH PAPULE - PLAQUE NODULE PUSTULE - CYST VESICLE - BULLAE WHEAL
Define macule skin lesions
- Small
- Flat circumscribed skin discolorations
- Lacking surface elevation or depression
Define patch skin lesions
- Large
- Flat circumscribed skin discolorations
- Lacking surface elevation or depression
- A very large macule
Define papule skin lesions
- Elevated solid lesion
2. <5mm
Define plaque skin lesions
- Elevated solid confluence of papules
- > 5mm
- Lacking a deep component
Define nodule skin lesions
- Elevated solid lesion
- > 5mm
- A larger and deeper paple
Define pustule skin lesions
- Papule that contains
Purulent material - <5mm
- Not necessarily infected
Define cystic skin lesions
Nodule that contains
fluid or semisolid material
Define vesicular skin lesions
- Papule that contains clear fluid
- <5mm
- called hemorrhagic vesicle if filled with blood
Define bullae skin lesions
- Localized fluid collection
- A large vesicle
- > 5mm
- called hemorrhagic bullae if filled with blood
Define wheal skin lesions
- Firm edematous plaque
That is evanescent (coming and going) and pruritic - Hives
What terms are used to describe secondary skin lesions
SCALE - CRUST
EROSION - ULCER
FISSURE - EXCORIATION
SCAR
Define scale skin lesions
Thickened Stratum Corneum
secondary to keratinocyte hyperproliferation
Define crust skin lesions
Collection of cellular debris
Dried serum, blood = Scab
Define erosion skin lesions
Superficial focal loss of epidermis
Heals without scarring
Define ulcer skin lesions
Full thickness focal loss of epidermis and dermis
Heals with scarring
Define fissure skin lesions
Verticle loss of epidermis and dermis Sharply defined walls
“Cracking” skin
Define excoriation skin lesions
Linear erosion induced by scratching
Define scarring
A collection of new connective tissue
Implies dermoepidermal damage
May be hypertrophic (too much collagen-raised scar) or atrophic (too little collagen-depressed scar)
What terms are used to describe special lesions?
TELANGIECTASIAS PETECHIAE - PURPURA COMEDONES TARGET LESIONS STRIAE BURROW
Define TELANGIECTASIAS
skin lesions
Small dilated superficial blood vessels
Blanchable
Define petechiae
skin lesions
Extravasation of RBC’s into Dermis
Non-Blanchable
<5mm
Define purpura
skin lesions
Extravasation of RBC’s into Dermis
Non-Blanchable
>5mm
Can turn into ecchymosis
Define comedomes
skin lesions, open vs. closed
Folliculocentric collection of sebum and keratin
Closed Comedone = “whitehead”
Open Comedone = blackhead, due to oxidation bc exposed to air
Define target
skin lesions
Consist of three zones
Center bulls eye
Second pale zone
Third rim of erythema
Define striae
skin lesions
Irreversible atrophic violaceous linear damage to skin “stretch marks”
Secondary to Topical Steroids overuse
Cushings Syndrome or Excessive rapid growth
Define burrows
skin lesions
Elevated channel in the superficial epidermis
Produced by parasites (Scabies, Hookworm)
What terms are used to describe the characteristic arrangements of skin lesions? When are they used?
ANNULAR GYRATE DERMATOMAL LINEAR GROUPED KOEBNERIZATION Remember to use them in the “description template” just after the type of skin lesions
Define annular
skin lesions
Ring shaped
Define gyrate
skin lesions
From Latin – “to turn in a circle”
Define dermatomal
skin lesions
Follows neurocutaneous dermatomes
Define linear
skin lesions
Skin lesions in a linear configuration
Define grouped
skin lesions
Skin lesions in a grouped configuration
Define koebnerization
skin lesions
Traumatized skin produces lesions
Koebner Phenomenon occurs with only certain skin diseases (LP, LN, PSOR)
What terms are used to describe specific patterns of distribution?
Bilateral - Unilateral
Flexural - Extensor
Malar
What diagnostic techniques in dermatology?
Skin Scrapings Woods Lamp Cultures Patch Test Skin Biopsies
What are the types of skin scrapings?
KOH, Tzanck Smears, and Scabies Smears
What are the different solvents used in skin scrapings?
- KOH Stain = Potassium Hydroxide
- Tzanck Smear = Giemsa, Wrights, or Sedi stains
- Scabies Smear = Mineral Oil, KOH, Saline
What is the most sensitive in office skin scraping technique?
KOH
What is KOH skin scraping used for?
Can aid in identifying
Tinea/Candida infections
HOW IS A KOH SKIN SCRAPING DONE CORRECTLY WHEN LOOKING FOR TINEA?
Sample correct area
Tops of vesicles
Leading edge of Annular Lesions
Deep Scrapings of Nails for subungual debris
What is the Tzanck smear used for? What are the limitations?
- Standard microscopic test for rapid Dx of Herpes infection
- cannot distinguish between the types of herpes (HSV ½ or VZV)
What is the desired target of Tzanck smear?
Looking for Atypical Keratinocytes with Lg Nuclei
Multinucleated Giant Cells
HOW IS A TZANCK SMEAR DONE?
1. Sample correct area A. Scrape base of “vesicle/bulla” B. Sample only a “Fresh” lesion 2. Follow these steps A. Use #15 blade to correct area and transfer to slide B. Stain with either Giemsa, Wrights, or Sedi stain C. Coverslip D. Look for “Multinucleated Giant Cells”
What is the etiology of scabies?
Caused by a mite Sarcoptes Scabiei var. hominis
How is scabies diagnosed?
Diagnosis is made by identifying the female mite, her eggs, or fecal material under the microscope
HOW IS A SCABIES SMEAR DONE?
- Sample correct area
A. Scrape “Burrows”, vesicles, or papules
B. Have patient point with index finger to itchy area
C. Important to sample - finger webs, flexural wrists, genitalia - Follow these steps
A. Apply Mineral oil to sample area
B. Use #15 blade and vigorously scrape area
(ok to scrape til small amount of bleeding)
C. Coverslip
D. Look for Female Mite, Eggs, or Fecal Material
E. Mites also seen using KOH or Saline wet mount Preps
What is the Wood’s lamp exam?
Fluorescing affected areas with invisible
“Black Light” (long wave UV radiation)
What does the Wood’s lamp exam aid in identification of? What are the diagnostic colors of certain pathogens?
- Tinea Capitis infections (non T. Tonsurans) = yellow-green
- Tinea Versicolor – dull yellow
- Erythrasma – coral red
- Pseudomonal – green
- Vitiligo – accentuates epidermal pigment if present
What are the best methods for bacterial culture swab?
- Best yield when superficial infection
- Swab vigorously area of most inflammation
- Results in about 1 wk
What are the best methods for viral culture swab?
Keep Refrigerated
Best to sample base of fresh vesicle or bullae
Results in about 1 wk
What are the best methods for fungal culture swab?
- DTM – Turns Red if Dermatophyte is present (no ID)Results over several wks
- Sabouraud’s Dextrose Agar – Used to ID type of Dermatophyte Results over a month
What is the test of choice to differentiate between contact allergic vs. irritant dermatitis?
Patch test
Define allergic contact dermatitis
- Immunologically mediated
2. An acquired sensitivity affecting certain individuals
Define irritant contact dermatitis
- Is not immunologically mediated
2. Due more to chemical damage to skin
When are skin biopsies the best diagnostic technique?
For cutaneous neoplasms that cannont be Dx clinically
When are skin biopsies a helpful diagnostic technique?
In inflammatory skin disorders of uncertain etiology
What are skin biopsy samples used for?
H&E histology examination
Specialized studies such as Immunofluorescence, electron microscopy, cultures, special stains, PCR studies, etc.
What are the different types of skin biopsies? What are the most common types?
CURETTE BIOPSY SCISSOR BIOPSY SHAVE BIOPSY PUNCH BIOPSY INCISIONAL BIOPSY EXCISIONAL BIOPSY 2. Shave and punch
What are the in office treatment procedures for derm?
Lasers, Light Therapy, Phototherapy, and PDT
Resurfacing Procedures
Injectables