1 - Diagnosis Flashcards
Slide 3
Anatomy review
Functions of epidermis
Barrier to pathogens
Water regulation
Thinnest epidermis
0.3mm (eyelids)
Thickest epidermis
3mm (back)
What are the 5 layers of
- Basal - constantly dividing keratinocytes (melanocytes located here)
- Spinosum - keratinocytes connected by desmosomes (Langerhans cells located here)
- Granulosum - keratinocytes lose nuclei and continue to flatten, appear granular
- Lucidum - appear lucent, very thin, in thickest skin area
- Corneum - consists of dead cells, primary barrier function
Recommended approach to skin disease:
History
Physical (distribution, primary lesion, secondary and/or special lesions)
DDx
Tests
Brief Hx should include
Duration, rate of onset, location, sxs
FHx
Allergies
Occupation
Previous w/u and Txt?
Meds
PMH
Sexual contact(s)
Examining the lesion
Distribution pattern and extent of the eruption by having pt disrobe
Examine carefully (hands lens, magnification, good lightning)
Check for secondary and special lesions
Make sure to include in your PE:
Mucous membranes
Genital and anal regions
Hair
Nails
Peripheral lymph nodes
Describe the lesion:
Number
Size (cm)
Color
Primary lesions, secondary lesions, special lesions
Distribution
Slide 12
Good example of how to be super descriptive and wow your derm preceptor
Intertriginous means:
Under a skin fold (i.e. under-boob)
Most skin diseases begin with:
A basic lesion that if referred to as a primary lesions
ID’ing the primary lesion is critical
Allows for the formulation of DDx
Examples of primary lesions
Macule
Papule
Plaque
Nodule
Pustule
Vesicle
Bulla
Wheal
What is a macule?
Circumscribed, flat discoloration
What is a patch?
Some refer to a macule that is greater than 1cm as a “patch”
What is a papule?
An elevated solid lesions up to 0.5cm in diameter; color varies
May become confluent and form plaques
What is a plaque?
A circumscribed, elevated, superficial, solid lesion more than 0.5cm in diamteter
Often formed by the confluence of papules
What is a nodule?
A circumscribed, elevated, solid lesions more than 0.5cm in diameter
A large nodule is referred to as a tumor
What is a pustule?
A circumscribed collection of leukocytes and free fluid that varies in size
What is a vesicle?
A circumscribed collection of free fluid up to 0.5cm in diameter
What is a bulla?
A circumscribed collection of free fluid more than 0.5cm in diameter
What is a wheal?
Hive
A firm, edematous plaque resulting from infiltration of the dermis with fluid
Wheals are transient and may last only a few hours
Secondary lesions
Develop during the process of skin dz
Or are created by scratching or infection
Ex. Scale, crust, erosion, ulcer, fissure, atrophy, scar
Scales
Excess dead epidermal cells that are produced by abnormal keratinization and shedding
Crust
A collection of dried serum and cellular debris
A scab
Erosion
A focal loss of epidermis
Erosions do NOT penetrate below the dermoepidermal junction and therefore heal without scarring
Ulcer
A focal loss of epidermis AND dermis
Heal with scarring
Fissure
A linear loss of epidermis and dermis with sharply defined, nearly vertical walls
Atrophy
A depression in the skin resulting from thinning of the epidermis or dermis
Scar
Abnormal formation of connective tissue implying dermal damage
After injury or surgery, scars are initially thick and pink but with time become white and atrophic
Examples of special skin lesions
Excoriation
Comedone
Milia
Cyst
Burrow
Lichenification
Telagniectasia
Petechiae
Purpura
Excoriation
An erosion caused by scratching
Often linear
Comedone
A plug of sebaceous and keratinous material lodged in the opening of a hair follicle
The follicular orifice may be dilated (blackhead) or narrowed (whitehead)
Milia
A small, superficial keratin cyst with no visible opening
Common in newborns
Cyst
A circumscribed lesion with a wall and a lumen
Lumen may contain fluid or solid matter
Burrow
A narrow, elevated, tortuous channel produced by a parasite
Lichenification
An area of thickened epidermis induced by scratching
The skin lines are accentuated so that the surface looks like a washboard
Telangiectasia
Dilated superficial blood vessels
Petechiae
A circumscribed deposit of blood LESS than 0.5cm
Purpura
A circumscribed deposit of blood GREATER than 0.5cm
Tests
Biopsy (shave, punch, excisional)
KOH (fungus)
Skin scraping (scabies)
Gram stain
Cx (fungal, bacterial)
Cytology (Tzanck prep for herpes)
Wood’s lamp (fungal, bacterial)
Patch testing (allergies)
Blood (RPR/VDRL, CBC, ESR, HIV)
Dermoscopy (pigmented lesions, R/O MM)
Don’t prescribe meds unless you:
Have an actual diagnosis established
Experimentation is tempting, and then if that fails refer to derm…don’t do it.
What are the four main treatment categories?
Topical
Systemic
Surgical
Phototherapy
We dont have a diagnosis for your rash
So were gonna rub some money on it and see what happens
