Dermatology

Question 1

Bullous pemphigoid

Answer 1

antibodies to hemidesmosomes (connect basal keratinocytes to basement membrane in basal layer of epidermis)

Question 2

Pemphigus vulgaris

Answer 2

antibodies to desmosomes (connect keratinocytes to each other in epidermis)

Question 3

Xeroderma pigmentosum

Answer 3

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

Question 4

Hypohidrotic ectodermal dysplasia

Answer 4

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

Question 5

What are the 3 layers of the skin and their resident cells?

Answer 5

Epidermis - keratinocytes, melanocytes, Langerhans cells, Merkel cells
Dermis - fibroblasts, collagen, elastic, blood vessels, nerve endings
Subcutis - fat, blood vessels, fibrous septae

Question 6

What are the 4 layers of the Epidermis and their resident cells/materials?

Answer 6

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

Question 7

Melanocytes

Answer 7

melanin (pigment) -producing dendritic cells derived from neural crest; located among the basal cells in the epidermis, about 1MC:10KCs

Question 8

Langerhans cells

Answer 8

Dendritic cells (APCs) in mid-epidermis; they recognize antigens, phagocytose, process, and present to LCs in regional lymph nodes

Question 9

Merkel cells

Answer 9

epidermal cells associated with light touch sensation

Question 10

Apocrine vs. Eccrine sweat glands

Answer 10

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)

Question 11

Epidermolysis Bullosa Simplex

Answer 11

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

Question 12

Psoriasis

Answer 12

• 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

Question 13

Toxic epidermal necrolysis

Answer 13

often drug-induced, acute (dermatologic emergency) necrosis and sloughing of the epidermis

Question 14

Atopic dermatitis

Answer 14

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

Question 15

Tx algorithm for acne

Answer 15

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

Question 16

Tx for Rosacea

Answer 16

Topical:
Metronidazole, Azelaic acid, Sodium sulfacetamide w/ sulfur
Systemic:
Oral Tetracyclines
Other options for tx: IPL, Laser, Surgery

Question 17

Tx for perioroficial dermatitis

Answer 17

Discontinue all topical steroids
Mild: Topical Abx
Severe: Oral Abx - may require topical NSAID

Question 18

Folliculitis

Answer 18

Causes: bacterial- S. aureus, Streptococcus, Pseudomonas
fungal- Pityrosporum orbiculare
mite- Demodex folliculorum

Tx: Abx soap/wash
Top. Abx
Top. antifungal

Question 19

Hidradenitis Suppurativa

Answer 19

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

Question 20

Herpes Simplex Virus

Answer 20

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

Question 21

Herpes Zoster Virus (VZV [varicella zoster virus])

Answer 21

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

Question 22

Molluscum Contagiosum

Answer 22

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

Question 23

Warts

Answer 23

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

Question 24

HPV vaccine

Answer 24

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.

Question 25

List the 5 genera that cause fungal/yeast skin infections.

Answer 25

Dermatophytes:
Trychophyton (#1 cause)
Microsporum
Epidermophyton

Yeasts:
Tinea versicolor
Candidiasis

Question 26

Tinea capitis

Answer 26

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

Question 27

Tinea corporis

Answer 27

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

Question 28

Tinea mannum

Answer 28

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

Question 29

Tinea Cruris

Answer 29

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

Question 30

Tinea pedis

Answer 30

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)

Question 31

Tinea unguinum

Answer 31

Nail infection
Old men
RF’s: IS’d, diabetes, HIV, poor circulation, trauma, dystrophy
Proximal nail affected: HIV

Question 32

Chronic paronychia

Answer 32

nasty ass nails for a long time. Tx w/ topical ketoconazole if mild, oral fluconazole if severe.

Question 33

Trachyonychia

Answer 33

20 nasty ass nails

idiopathic, lichen planus, psoriasis, other

Question 34

Beau’s lines

Answer 34

Beau be stressin, she gets depressions in her nails

Question 35

Line of deformity midline down length of nail.

Answer 35

Quit picking at your cuticles

Question 36

Tx for nail fungal problems

Answer 36

Topicals not effective
Penlac (Afx nail lacquer)

Systemic: Griseofulvin, Lamisil

Question 37

Tinea versicolor

Answer 37

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

Question 38

Candidiasis

Answer 38

Intertriginous, paronychia, angular cheilitis (painful, erythematous fissures, pustules)
Tx- antiyeast cream, decrease moisture