Primary Care Dermatology - Welcome to...
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Transcript of Primary Care Dermatology - Welcome to...
Primary Care Dermatology
Kara Mudd, MSPAS, PA-C
The Skin
• Accounts for ~15% of the total body weight and is the largest organ in the
human body.
• The Skin serves many functions
• Physical barrier to chemical or mechanical insults, microbes, regulates hydration
• Sensory- mechanoreceptors
• Metabolic- Vit D3 synthesis
• Immunologic protection
• Thermoregulation
Anatomy of the skin
Anatomy of the skin
• The skin is made up of three main layers
• Epidermis
• Dermis
• Subcutis/Subcutaneous layer
Anatomy of the skin
• Epidermis – made up mainly of keratinocytes (90%)
• Layers of the Epidermis- (Come Lets Get Sun burned)
• Stratum Corneum- Made up of desquamating keratinocytes.
• Stratum Lucidum (present in palms and soles)
• Stratum Granulosum- Keratinocytes secrete lipids into the extracellular space in this
layer to give the skin its water protective barrier as well as helping the skin to retain moisture
• Stratum Spinosum- desmosomes between keratinocytes hold the cells together and give this layer a “spiny” look under the microscope
• Stratum Basale- Epidermal stem cells divide here to start keratinization
Anatomy of the skin
Anatomy of the skin
• Epidermis – made up mainly of keratinocytes.
• Keratinocytes- This is the predominant cell type in the epidermis. In the basal
layer keratinocytes are referred to as basal cells. They undergo multiplication
and migrate up through the layers of the epidermis. They accumulate keratin
as they move upward through the layers and are shed through desquamation.
This cycle takes approximately 30 days.
Anatomy of the skin - Epidermis
• Melanocytes- Found among the basal layer and in hair follicles. Produce
melanin in melanosomes that protect the nucleus of neighboring
keratinocytes.
• Langerhans Cells – Antigen- presenting cells, most often in the spinous
layer. Bind and present antigens to T lymphocytes. Important in delayed-
type hypersensitivity.
• Merkel Cells- mechanoreceptors for light touch. Increased numbers in
sensitive skin.
Anatomy of the skin
• Dermal-Epidermal Junction
• Separated by the basement membrane.
• Dermal papillae and epidermal rete ridges help facilitate the stability of the
junction
• If this junction is affected it can cause blistering
Anatomy of the skin
Anatomy of the skin
• Dermis – Layer of connective tissue that supports the epidermis and binds it
to the subcutaneous tissue. Network of blood and lymphatic vessels.
Dermal vasculature has a thermoregulatory function. Also contains hair
follicles and sweat glands.
• Papillary Layer- thin contains the dermal papillae, collagen
• Reticular Layer- more dense type I collagen, elastic fibers
• Varying thickness based on area of the body. Maximum thickness 4mm.
Anatomy of the skin
• Adnexal Structures-
• Sebaceous Glands- secrete sebum, in dermis
• Hair follicle- epidermal invagination, keratin form hair shaft
• Sweat Gland
• Eccrine- widely distributed, direct opening onto skin, main role in thermoregulation
• Apocrine- connected to the hair follicle (axillae, areola, perianal, genital)
Anatomy of the skin - Pilosebaceous unit
Anatomy of the Skin- nails
• Cuticle- stratum corneum
• Nail Matrix produces nail
• Nail Plate- bound to epidermis
• Nail Bed- contains stratum basale and stratum spinousum
• Fingernails grown ~3mm/mo
• Toenails grow ~ 1mm/mo
Evaluation of the Dermatology Patient
Distribution of dermatologic diseases
Dermatology Terminology- Primary Lesions
Macule- Flat, nonpalpable, typically well circumscribed lesion <10 mm in
diameter
Dermatology Terminology- primary lesions
Papule- firm, palpable, well circumscribed <10mm diameter
Dermatology Terminology- primary lesions
Patch- flat, non palpable, >10mm diameter,
Dermatology Terminology
Nodule- raised, palpable lesion, well circumscribed >10 mm in diameter,
deeper in dermis
Dermatology Terminology
Plaque- raised flat top lesion, > 10mm, may be a group of confluent papules
Dermatology Terminology
Vesicle- elevated, well
circumscribed, containing serous
fluid, < 10mm
Bulla- well circumscribed, raised, fluid
filled, >10mm
Dermatology Terminology
Wheal- elevated, irregular shaped area of edema, transient
Dermatology Terminology
Pustule- elevated, superficial, filled with purulent fluid
Dermatology Terminology
Telangiectasia- fine capillary dilation
Dermatology Terminology
Cyst- elevated, encapsulated lesion filled with liquid or semi-solid
Dermatology Terminology
Petechiae/Purpura- extravasation of red blood cells, non blanching
Dermatology Terminology
Atrophy-thinning of skin, skin becomes paper like
Dermatology Terminology
Erosion- Loss of part of the epidermis, follows rupture of vesicle/bulla
Dermatology Terminology
Excoriation- loss of the epidermis, often with eschar
Ex: scratch, scabies
Dermatology Terminology
Fissure- linear break all the way to the dermis
Dermatology Terminology
Lichenification- thickened epidermis, well circumscribed
Dermatology Terminology
Scale- desquamation, keratinized cells
Dermatology Terminology
Scar- fibrous tissue that replaces normal skin following an injury
Dermatology Terminology
Ulcer- loss of epidermis and dermis
Dermatology Terminology
Crust- hardened serum, blood or purulent exudates
Dermatology Terminology
Verrucous- rough surface
Diagnostic Tests
• Diascopy- Using a diascope or glass slide pressed up to the skin to
evaluate for intact capillaries vs. extravasated blood.
Diagnostic Tests
• Mineral Oil scraping for mites-
Diagnostic Tests
• KOH prep- If it’s scaly scrape it
Diagnostic Tests
• Tzanck Smear-
• De-roof vesicle and put fluid
on slide, stain with methylene
blue.
• Mutinucleated giant cells are
diagnostic for herpes
infection.
• Viral culture is more practical
and used clinically.
Diagnostic Tests
• Woods Light examination-
• Loss of pigment in Vitiligo.
Depigmented skin fluoresces.
• Tinea Versicolor- yellow
• Erythrasma- corynebacteria
fluoresces coral/pink
• Pseudomonas- green
Diagnostic Tests
• Patch Testing-
Diagnostic Tests
• Biopsy
• Shave biopsy-
• Used for superficial lesions. Skin Cancers, SK’s,
nevi.
• Only removes a thin layer of tissue
• Do not use for inflammatory conditions
• Wound care: wash daily with soap and water.
Apply Vaseline and a bandage daily.
• Do NOT use for suspected Melanoma
Diagnostic Tests
• Biopsy
• Punch biopsy
• Used when the dermis or subcutaneous tissue
needs to be sampled, also could be used for
definitive removal.
• 2-10mm punch biopsies are available. 4mm is
standard.
• Needs to be closed with suture which are
removed in 7 days on face and 10 days on the
trunk or extremities.
• Wound care: wash daily with soap and water.
Apply Vaseline and a bandage daily.
Diagnostic Tests
• Biopsy
• Incisional biopsy- Deep incision to remove a larger
piece of tissue down to the subcutaneous tissue but
not the entire lesion. Often used in a widespread rash
or to take a sample of a large lesion. Closed with
subcutaneous and superficial sutures.
• Excisional biopsy- Excision to attempt to remove the
entire lesion. Could be performed in the case of a
suspected malignancy (malignant melanoma). If
margins not clear would have to go back for wider
excision.
Diagnostic Tests
• Cultures
• Viral Culture- VZV, HSVI/II
• Bacterial Culture- aerobic/anaerobic
• Fungal Culture- onychomycosis, tinea corporis etc.
Questions?
References
• Berger TG. Dermatologic Disorders. In: Papadakis MA, McPhee SJ, Rabow MW.eds. Current Medical Diagnosis & Treatment 2015. New York, NY: McGraw-Hill; 2014.
• Farmer P, Rhatigan J. Global Issues in Medicine. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015.
• Garg A, Levin NA, Bernhard JD. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolff K. eds. Fitzpatrick's Dermatology in General Medicine, 8e. New York, NY: McGraw-Hill; 2012.
• Khan SA, Bank J, Song DH, Choi EA. The Skin and Subcutaneous Tissue. In:Brunicardi F, Andersen DK, BilliarTR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. eds. Schwartz's Principles of Surgery, 10e. New York, NY: McGraw-Hill; 2014. LeBlond RF, Brown DD, Suneja M, Szot JF. The Skin and Nails. In: LeBlond RF, Brown DD, Suneja M, Szot JF. eds. DeGowin’s Diagnostic Examination, 10e. New York, NY: McGraw-Hill; 2015.
• Mescher AL. Chapter 18. Skin. In: Mescher AL. eds. Junqueira's Basic Histology: Text & Atlas, 13e. New York, NY: McGraw-Hill; 2013.
References
• Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr.. In: Usatine RP, Smith MA,
Chumley HS, Mayeaux EJ, Jr.. eds. The Color Atlas of Family Medicine, 2e. New
York, NY: McGraw-Hill; 2013.
• Wolff K, Johnson R, Saavedra AP. In: Wolff K, Johnson R, Saavedra
AP. eds. Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology, 7e. New
York, NY: McGraw-Hill; 2013.