Dermatology Flashcards
Bullous pemphigoid
antibodies to hemidesmosomes (connect basal keratinocytes to basement membrane in basal layer of epidermis)
Pemphigus vulgaris
antibodies to desmosomes (connect keratinocytes to each other in epidermis)
Xeroderma pigmentosum
AR genetic disorder in which the pt has ineffective DNA repair mechanisms; results in several base cell carcinomas, malignant melanomas, and squamous cell carcinomas in XP pts who are exposed to sunlight
Hypohidrotic ectodermal dysplasia
thermoregulation disorder:
mutation in EDAR gene (protein for proper interaction btw developing ectoderm and mesoderm) results in an inability to regulate temperature, so these pts overheat easily, and also have abnormal hair follicles, sweat glands, and teeth
What are the 3 layers of the skin and their resident cells?
Epidermis - keratinocytes, melanocytes, Langerhans cells, Merkel cells
Dermis - fibroblasts, collagen, elastic, blood vessels, nerve endings
Subcutis - fat, blood vessels, fibrous septae
What are the 4 layers of the Epidermis and their resident cells/materials?
BOTTOM - stratum basale/basal layer, stem cells that give rise to new KCs
Next up - stratum spinosum, where the cells differentiate and appear spiny because of the visible desmosomes connecting the KC to each other; also has lamellar (lipid) granules for barrier function
Almost to the top - stratum granulosum, where the cells appear granular because they are synthesizing the IC keratohyaline granules; also here the lamellar granules are secreted into the ECM for water barrier
TOP - stratum corneum, where the cells are flat and function as the barrier-most layer where keratins and filaggrins create protective layer and keep water in the cells
Melanocytes
melanin (pigment) -producing dendritic cells derived from neural crest; located among the basal cells in the epidermis, about 1MC:10KCs
Langerhans cells
Dendritic cells (APCs) in mid-epidermis; they recognize antigens, phagocytose, process, and present to LCs in regional lymph nodes
Merkel cells
epidermal cells associated with light touch sensation
Apocrine vs. Eccrine sweat glands
Apocrine glands are associated with hair follicles, component of the pilosebaceous unit
Eccrine glands are the “true” sweat glands that open directly onto the skin (not associated with hair follicle)
Epidermolysis Bullosa Simplex
genetic mutation in keratin 5 or 14; causes blistering and basal KC fragility, so the KCs break off when they should be attached by keratins to the hemidesmosome plate
Psoriasis
- long-lasting autoimmune disease characterized by patches of abnormal skin that are typically red, itchy, and scaly.
- etiology unknown but believed to be based in genetics, chronic infections, HIV, or drug-induced
- highly associated with metabolic syndrome, CVD, and obesity
Toxic epidermal necrolysis
often drug-induced, acute (dermatologic emergency) necrosis and sloughing of the epidermis
Atopic dermatitis
inflammatory condition of the skin that results in itchy, red, swollen, and cracked skin; cause is not known but believed to involve genetics, immune system dysfunction, environmental exposures, and difficulties with the permeability of the skin
Tx algorithm for acne
Mild comedonal: Top. retinoid
Mild inflammatory/mixed: Top. retinoid + top. abx
Moderate inflammatory/mixed: top. retinoid + top. abx + oral abx
Severe inflammatory/refractory to treatment:
minimal scarring: top. retinoid + top. abx + oral abx
scarring/multiple tx failures: Isotretinoin
Topical combos: Tretinoin + clindamycin
Adapalene + benzoyl peroxide
Tx for Rosacea
Topical:
Metronidazole, Azelaic acid, Sodium sulfacetamide w/ sulfur
Systemic:
Oral Tetracyclines
Other options for tx: IPL, Laser, Surgery
Tx for perioroficial dermatitis
Discontinue all topical steroids
Mild: Topical Abx
Severe: Oral Abx - may require topical NSAID
Folliculitis
Causes: bacterial- S. aureus, Streptococcus, Pseudomonas
fungal- Pityrosporum orbiculare
mite- Demodex folliculorum
Tx: Abx soap/wash
Top. Abx
Top. antifungal
Hidradenitis Suppurativa
Suppurative abscesses found in the axilla/inframammary folds and pannus of fat women who smoke.
Gaping holes in skin that leak nastiness.
Treat mild cases w/ topical or oral Abx
Treat moderate/severe cases with IL steroids, TNF-a inihibitors, surgery
Herpes Simplex Virus
Primary, latent, recurrent
HSV-1 = Above waist herp (85% seropositive)
HSV-2= below waist herp (25% seropositive)
dsDNA
Direct contact (3-7 day incubation before prim. infection)
Latent inf. travels to ganglia via sensory nerves.
Viral shedding in saliva/genital secretions
Prim. infection: burning, tingling, pain, fever, malaise, LAD
Recurrent inf.: tends to be milder
Triggers of flare: fever, sun exposure, stress (?)
Clinical pres: clusters of monomorphic vesicles, “punched out” erosions & crusted papules
Confirm Dx w/ Tzanck smear - look for multinucleated giant cells. Also viral culture & PCR.
Tx: mild- topical antiviral severe- oral or IV antiviral
Herpes Zoster Virus (VZV [varicella zoster virus])
Cause shingles- reactivation of latent infection
Up to 30% lifetime risk of shingles. More common after 60yo & immunosuppressed pts
dsDNA
Hangs out (latent) in dorsal root ganglia
Triggers: trauma, stress, fever, radiation, immunosuppression
Clinical: Prodrome- pain, itching, burning
Grouped vesicles over a dermatome
Trunk most common
Lesions at tip of nose (V1) - Hutchinson’s sign (nasociliary branch) could lead to blindness
V2/3- facial palsy, ertigo, deafness
Rash resolves 3-5 wks
Postherpetic neuralgia in 5-20% over 40yo
Confirm Dx w/ Tzanck smear, viral culture, PCR
Tx w/ oral antivirals within 72 hrs
Vaccine Zostavax for pts
Molluscum Contagiosum
Cutaneous infection caused by Pox virus
dsDNA
generally skin-skin contact. can autoinoculate, fomite.
resolves spontaneously
pink-skin colored, dome-shaped, waxy papules
+/- central umbilication
May cause mulluscum dermatitis (itchy rash)
Can occur anywhere on body
Can be confused for acne or folliculitis (look for comedones)
Tx- nothing really works well.
live with it.
curettage
cryotherapy
cantharidin (topical vesicant) 90% clearance after 2 appl.
Immunomodulators (Imiquimod- stim. TH1 cells to fight infection, cimetidine- blocks H2 receptor of T-cell repressor cells)
Retinoids, keratolytics
Warts
HPV
Take time to Tx
dsDNA
more than 100 serotypes
Appear anywhere
Benign, involute, can be painful
Can be oncogenic (16, 18, 31, 33)
Trans: contact, autoinoculation, fomite (don’t share towels w/ warty ppl)
2/3 resolve within 2 yrs w/o tx
Verrucae vulgaris- common wart
Verrucae plantaris- foot wart (pts hate these)
Verrucae plana- flat wart (face) shaving spreads
Condylomata acuminata- anogenital warts
Clue to Dx- parring reveals black dots
No good Tx. By all means, put some duct tape on your butthole.
But…immunomodulators & destructive methods may be implemented by physician
HPV vaccine
Gardasil (protects against serotypes 6, 16, 18, 11)
Cervarix (protects against 16 & 18)
preventing infection reduces risk of cervical cancer and mouth/throat cancers in males & females.
List the 5 genera that cause fungal/yeast skin infections.
Dermatophytes:
Trychophyton (#1 cause)
Microsporum
Epidermophyton
Yeasts:
Tinea versicolor
Candidiasis
Tinea capitis
Scalp “ringworm”
Most common in children (boys)
>90% caused by Trichophyton
acquired from cats & combs. fucking disgusting.
Clinical: patchy alopecia, scaling, dandruff, hair breakage, pustules (may be 2ndary bact’l inf.), KERION - (very inflammed, perm. hair loss).
Posterior cervical, ub-occipital LAD
Confirm Dx: Scraping (micro), Fungal culture
KOH breaks down skin cells so you can better visualize fungus on slide from scraping.
DDx: seborrheic dermatitis, psoriasis, alopecia areata (no lesion)
Tx- systemic antifungals (Griseofulvin) Microsporum may require higher dose (that’s why culture is important)
Antifungal shampoo 2-3x week
Terbinafine- inhibits ergosterol synth. x6 wks
Use of systemic azoles limited to infants
Tinea corporis
Superficial fungal infection of skin
Contact w/ infected person/animal
Clinical- 1 or more well defined annular scaly, erythematous plaques w/ central clearing and a scaly, vesicular, papular, or pustular border.
Majocchi’s Granuloma- granulomatous folliculitis. deeper infection of follicles
Dx- history/physical, KOH, fungal culture
DDx: Nummular atopic dermatitis (not annular, very itchy),
psoriasis (silver/white scale), granuloma annulare (no scale, raised rubbery rim)
Tx- topical Afx
Systemic Afx for IC’d, Majocchi’s, tinea faciei
Don’t use topical steroid/Afx combinations- bad side fx
Tinea mannum
Fungal infection of hands Males Dry scaly hands Dx- KOH, fungal culture DDx- other dermatitis, psoriasis Tx- Dorsum of hand: topical Afx Palm- oral Afx
Tinea Cruris
Skin of groin
“jock itch”
Men
Risk factors: Obesity, heat, humidity
Pruritic, penis/scrotum not affected
DDx- candidiasis, Erythrasma (bacterial), psoriasis
Tx- topical Afx. Oral Afx if severe, refractory to tx
Tinea pedis
Athlete’s foot
Males
Itchy, scale on soles, btwn toes. Moccasin- fine, dry scale over soles.
Vesiculobullous- vesicles, bullae on soles (esp. insteps)
Dx- KOH, fungal culture
DDx- contact dermatitis, dishydrotic eczema (tapioca vesicles)
Tinea unguinum
Nail infection
Old men
RF’s: IS’d, diabetes, HIV, poor circulation, trauma, dystrophy
Proximal nail affected: HIV
Chronic paronychia
nasty ass nails for a long time. Tx w/ topical ketoconazole if mild, oral fluconazole if severe.
Trachyonychia
20 nasty ass nails
idiopathic, lichen planus, psoriasis, other
Beau’s lines
Beau be stressin, she gets depressions in her nails
Line of deformity midline down length of nail.
Quit picking at your cuticles
Tx for nail fungal problems
Topicals not effective
Penlac (Afx nail lacquer)
Systemic: Griseofulvin, Lamisil
Tinea versicolor
Common superficial fungus of skin
Normal skin flora
Causes skin hyper/hypopigmentation due to azeliac acid production
Clinical: multiple scaling/oval papules
Dx- KOH (look for spaghetti & meatballs)
DDx- Pityriasis alba (face color fades slightly)
Tx- topical shampoo
Severe- ketoconazole, fluconazole
Candidiasis
Intertriginous, paronychia, angular cheilitis (painful, erythematous fissures, pustules)
Tx- antiyeast cream, decrease moisture
