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USMLE Step 3 - ALL > Dermatology > Flashcards

Dermatology Flashcards

1
Q

Age: 30-40s
bulllae - thin and fragile, painful NOT ITCHY
involves mouth
Nikolsky’s sign

A

Pemphigus Vulgaris

“so bad it’s vulgar”

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2
Q

Abs in Pemphigus Vulgaris

A

Abs against desmosomes (against Ags in the intercellular spaces of the epidermal cells)

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3
Q

In what conditions can you see Nikolsky’s sign

A

Pemphigus Vulgaris
Staphylococcal Scalded Skin Syndrome
Toxic Epidermal Necrolysis

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4
Q

Dx and Tx of Pemphigus Vulgaris

A

DX: bx of skin

TX: PO glucocorticosteroids

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5
Q

Age: 70-80s
bulllae - tense, thick (don’t rupture), painful, ITCHY
DOESN’T INVOLVE MOUTH
NO NIKOLSKY’S SIGN

A

Bullous Pemphigoid

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6
Q

Abs in Bullous Pemphigoid

A

Abs against hemidesmosomes (IgG and C3 deposits at dermal-epidermal junction)

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7
Q

Dx and Tx of Bullous Pemphigoid

A

DX: bx from edge of blister

TX: PO glucocorticosteroids

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8
Q

Non-healing PAINLESS blisters (increased fragility) on sun-exposed areas of the body (backs of hands and face)
Hyperpigmentation of skin
Hypertrichosis of face

A

Prophyria Cutanea Tarda

Def. in enzyme uroporphyrinogen decarboxylase = accumulation of porphyrins (in heme pathway)

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9
Q

What conditions are associated w/ Prophyria Cutanea Tarda

A

Hep C
OCPs
Alcoholism
Liver Disease

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10
Q

Dx and Tx of Prophyria Cutanea Tarda

A

DX: test for urinary uroporphyrins

TX:

  • stop alcohol, estrogen use
  • use sun protection
  • use phlebotomy
  • chloroquine to increase excretion of porphyrins
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11
Q

HSN Rxn Type I –> mediated by IgE and mast cell activation

wheals and hives
itching

A

Urticaria

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12
Q

Common causes of Urticaria

A 
MDXs
insect bites
foods 
emotions
contact w/ latex

Causes of Chronic urticaria:

  • cold
  • vibration
  • pressure on skin (dermatographism)
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13
Q

Tx of Urticaria

A 
Acute Therapy: 
H1 antihistamines (eg. diphenhydramine) 
PO steroids (if life threatening)

Chronic Therapy:
Non-sedating antihistamines (eg. loratadine)
Desensitization (if trigger can’t be avoided)

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14
Q

Milder version of urticaria
Generally due to MDXs the pt is allergic to
Maculopapular eruption that blanches w/ pressure

A

Morbiliform Rash

TX: antihistamines

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15
Q

Targetlike lesions that can be confluent
On palms and soles
NO mucous membrane involvement

Nonspecific prodrome: fever, malaise, sore throat

A

Erythema Multiforme

TX: antihistamines

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16
Q

Causes of Erythema Multiforme

A

Infxn w/ herpes simplex (MCC) or mycoplasma
Malignancy and collagen vascular disease

MDXs:

  • PNC
  • NSAIDs
  • Sulfa drugs
  • Phenytoin
  • Allopurinol
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17
Q 
Acute flu-like prodrome 
Rapid onset red macules, vesicles, bullae
Mucous membrane involvement 
< 10-15% total body surface area 
Necrosis and sloughing of epidermis
A

Stevens-Johnson Syndrome

TX:

  • admit to burn unit
  • IVIG
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18
Q

Causes of Stevens-Johnson Syndrome

A

MDXs:

  • PNC
  • NSAIDs
  • Sulfa drugs
  • Phenytoin
  • Allopurinol
  • Phenobarbital
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19
Q

30-100% total body surface area
40-50% mortality rate
Nikolsky’s sign (skin sloughs off easily)

A

Toxic Epidermal Necrolysis

DX: skin bx
Causes: MDX (vs. Staphylococcal scalded skin syndrome caused by toxin from bacteria)

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20
Q

painful, red, raised nodules on anterior surface of shins

A

Erythema Nodosum

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21
Q

Causes of Erythema Nodosum

A

secondary to recent infxns (eg. strep) or inflammatory conditions including:

  • pregnancy
  • coccidioidomycosis
  • histoplasmosis
  • sarcoidosis (get CXR)
  • UC
  • syphilis
  • hepatitis
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22
Q

Tx of Erythema Nodosum

A

Analgesics + NSAIDs

Tx underlying dx

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23
Q

scattered papules w/ some red, SCALY areas on scalp
PATCHY HAIR LOSS
lymphadenopathy and SCARRING

A

Tinea Capitis

DX: KOH prep of hair shaft

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24
Q

Tx of Tinea Capitis

A

PO antifungal

  • -> griseofulvin
  • -> terbinafine
  • -> itraconazole

Prevent by not sharing hats/combs

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25
Q

Tx for nail fugal infxn

A

PO antifungal x 6 wks (fingernails) OR x 12 wks (toe nails)

  • -> griseofulvin
  • -> terbinafine
  • -> itraconazole
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26
Q

on arms/legs

red, itchy, scaly, RING-SHAPED lesions w/ raised borders that CLEAR CENTRALLY while expanding peripherally

A

Tinea Corporis

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27
Q

Tx for Tinea Corporis

A

PO griseofulvin

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28
Q

fungal infxn of hands
seen in pts w/ pre-existing tinea pedis
red, itchy, scaly, cracking lesions

A

Tinea Manuum

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29
Q

Tx of Tinea Manuum

A

Topical antifungal (eg. miconazole)

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30
Q

HYPOPIGMENTED or light brown or pink macules often found on back, shoulders, or neck
Macules DON’T TAN (more apparent in summer/spring)

A

Tinea Versicolor (due to Malassezia furfur)

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31
Q

Dx and Tx of Tinea Versicolor

A

DX: see hyphae and spores (spaghetti and meatballs)

TX:
First line: ketoconazole 2% shampoo (selenium sulfide shampoo)
PO antifungal (if resistant to tx)

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32
Q

Tx Guidelines for Nail or Scalp Fungal Infxn

A

use PO antifungals:

  • -> griseofulvin
  • -> terbinafine (SE: hepatotoxic)
  • -> itraconazole
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33
Q

Tx Guidelines for Fungal Infxn NOT involving hair or nail

A

use topical antifungals:

  • -> terbinafine (SE: hepatotoxic)
  • -> clotrimazole
  • -> ketoconazole (SEs: hepatotoxic, gynecomastia)
  • -> miconazole
  • -> nystatin
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34
Q

Tx Guidelines for Bacterial Skin Infections (eg. impetigo, cellulitis, folliculitis)

A

use PO dicloxacillin or cephalexin
use IV oxacillin or nafcillin OR IV cefazolin

if suspecting MRSA use IV vanc (PO equivalent = clindamycin, linezolid, Bactrim, doxycycline)

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35
Q

weeping, crusting, oozing of skin

small, yellow (“honey colored”) pustules on face especially child

A

Non-Bullous Impetigo

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36
Q

Cause and Predisposing Factors to Non-Bullous Impetigo

A

CAUSE:
S. aureus or S. pyogenes (Grp A Strep)

Predisposing Factors:
pre-existing skin trauma (eg. insect bite)
atopic dermatitis (eczema)

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37
Q

Tx of Non-Bullous Impetigo

A

TOPICAL mupirocin

Severe disease = PO dicloxacillin or cephalexin

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38
Q

Cause and Sxs of Bullous Impetigo

A

CAUSE:
S. aureus ONLY

SXs:
Rapidly growing flaccid bullae w/ yellow fld

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39
Q

Tx of Bullous Impetigo

A

PO dicloxacillin or cephalexin

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40
Q

abrupt onset
skin (eg. face) is bright red, hot and raised w/ sharp borders
area is painful and hyperesthetic to touch
fever, chills, malaise (systemic sxs)

A

Erysipelas

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41
Q

Tx of Erysipelas

A 
First Line: PO dicloxacillin or cephalexin 
Severe disease (w/ systemic sxs): IV oxacillin or nafcillin OR IV cefazolin
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42
Q

Complications of all skin infxns

A

Glomerulonephritis (NOT R. fever)

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43
Q

warm, red, swollen, tender skin

A

Cellulitis

44
Q

RFs for Cellulitis

A

obesity

disruption of skin (eg. by tinea pedis –> tx foot fungus in pts w/ recurrent cellulitis)

45
Q

Difference b/w Cellulitis or DVT

A

Cellulitis has ↑ WBCs and NO risks of hypecoagulability

46
Q

Cause of Cellulitis

A

S. aureus and S. pyogenes

47
Q

Tx of Cellulitis

A 
First Line: PO dicloxacillin or cephalexin 
Severe disease (w/ systemic sxs): IV oxacillin or nafcillin OR IV cefazolin
48
Q

Tx of Folliculitis

A

Topical mupirocin

49
Q

Tx of Furuncles and Carbuncles

A

PO dicloxacillin or cephalexin

50
Q

severe, life threatening infxn
cellulitis that dissects into the fascial planes of skin
very high fever
have hx of laceration, trauma, surgical procedure (portal of entry into skin)
pain out of proportion to superficial appearance
bullae
palpable crepitus (in C. perfringes infxn)

A

Necrotizing Fasciitis

51
Q

MC organisms involved in Necrotizing Fasciitis

A

Streptococcus (Grp A Strep) and Clostridia

52
Q

Dx of Necrotizing Fasciitis

A

↑ CPK
X-ray/CT/MRI –> shows air in tissue (black circles) or necrosis
Surgical debridement = BEST Dx and Tx

53
Q

Tx of Necrotizing Fasciitis

A

Surgical debridement
Broad spectrum ABX until cx results come back
–> piperacillin/tazobactam + Vancomycin + Clindamycin

Mortality rate = 80%

54
Q

Tx for Acute Herpes

A

PO acyclovir

Acyclovir - Resistant herpes = PO Foscarnet

55
Q

Herpetic Whitlow

A

non-purulent vesicles on hands

Tx: self-limited

56
Q

Ramsay Hunt Syndrome (herpes zoster oticus)

HERPES ZOSTER = SHINGLES = REACTIVATION OF VZV (VARICELLA = HHV 3)

A

ear manifestation of reactivated zoster virus:

  • -> ear pain
  • -> vesicles in external auditory canal
  • -> I/L facial paralysis
57
Q

Tx of Ramsay Hunt Syndrome (herpes zoster oticus)

A

IV acyclovir

58
Q

Who gets Zoster (VZV) vaccine?

A

≥ 60 yoa (not for HIV pts w/ CD4 <200, pregnant pts, pts w/ immunodeficiency or on immunosuppressive therapy)

59
Q

Who gets treated for Herpes Zoster/Varicella

A

Immunocompromised child OR primary infxn in adult

60
Q

Tx for Herpes Zoster/Varicella if:

pt comes w/in 72 hrs of rash vs. pt comes > 72 hrs after rash

A

Within 72 hrs of rash –> PO acyclovir or PO valacyclovir (better than acyclovir) to PREVENT postherpetic neuralgia (NOT to prevent rash from spreading)

> 72 hrs after rash –> give pain MDX and zinc oxide cream

61
Q

Acute Herpetic Neuralgia

A

persists ≤ 30 days from rash onset

Tx: NSAIDs, analgesics

62
Q

Subacute Herpetic Neuralgia

A

persists > 30 days but resolves within 4 months of rash onset

Tx: NSAIDs, analgesics

63
Q

Postherpetic Neuralgia

A

persists > 4mo from rash onset

Tx: Gabapentin, TCAs, pregabalin

64
Q

Tx of Primary (chancre) and Secondary Syphilis

A

IM PCN (single dose)

65
Q

cutaneous warts
–> hyperkeratotic papules on soles of foot
–> thickened, enlarging papule
infxn via skin to skin contact

A

Plantar Warts (from HPV)

Dx: scrapings of hyperkeratotic debris confirm dx

66
Q

Tx of Plantar Warts

A

initial = salicyclic acid (takes 2-3 wks to notice change)

67
Q

How is Scabies transmitted and Tx?

A

Person to person contact

Tx: 5% permethrin cream

  • -> must tx all household contacts and bedding/clothes need to be washed
  • -> if can’t use topical therapy (eg. in nursing home), then use PO ivermectin
68
Q

Tx for Lice?

A

5% permethrin cream

69
Q

Tx of Lyme rash

A

PO doxycycline or amoxocillin

70
Q

Fever > 102F
SBP <90
desquamative rash (diffuse, red macular rash –> like sunburn)
vomiting
involvement of mucous membranes of eye, mouth, genitals

↑ Cr, CPK, LFTs, Bands
↓ PLT

A

Toxic Shock Syndrome

–> caused by staph via exotoxin (TSS toxin 1)

71
Q

Tx for Toxic Shock Syndrome

A 
vigorous fld resuscitation 
antistaph MDXs (eg. nafcilin)
72
Q

superficial flaccid bullae, perioral crusting then subsequent scaling and desquamation
Nikolsky’s sign
NORMAL BP (unlike TSS)
NOT full thickness split (like TEN)

A

Staphylococcal Scalded Skin Syndrome

–> mediated by toxin from Staph

73
Q

Tx of Staphylococcal Scalded Skin Syndrome

A 
Manage in burn unit
Antistaph ABXs (ABXs don't reverse disease but they kill Staph that is producing toxin)
74
Q

papule appears then get central necrosis (black in color) surrounded by edematous ring –> “black eschar or black scab”

A

Anthrax

From Bacillus anthracis (in ppl with livestock contact)

TX: ciprofloxacin or doxycycline

75
Q

Dx and Tx of Melanoma

A

DX: excisional bx

TX: excision w/ wide margins

76
Q

Ocular Melanoma

A

primary malignant tumor arising from melanocytes w/in uvea

blurry vision, progressive and painless visual field abn

77
Q

Dx of Ocular Melanoma

A

U/S of eye

MRI (for staging)

78
Q

Tx of Ocular Melanoma

A

Asymptomatic pt w/ small lesions (diameter <10mm, thickness <3mm) –> observe w/o tx; repeat exam in 3 months and every 6 months thereafter

Symptomatic pt w/ large lesions (diameter ≥ 10mm, thickness ≥3mm) –> need radiotherapy

79
Q

stuck on appearance of hyperpigmented lesions

A

Seborrheic Keratosis

–> assoc. w/ GI and lung tumors (explosive onset of multiple pruritic lesions –Lesar Trelat sign)

80
Q

Precancerous lesions on sun-exposed areas in old ppl

rough, small, red papules w/ yellow/brown scales (“sandpaper like texture”)

A

Actinic Keratoses

  • -> can regress and recur
  • -> 20% risk of SCC

TX: sunscreen, 5-FU, cryotherapy

81
Q

suspect in pt w/ chronic scar that develops into non-healing, painless, bleeding ULCER
on sun-exposed areas in old ppl

A

Squamous Cell CA

DX: Punch Bx
TX: Mohs surgery (if don’t want surgery = radiation)
–> metastatic D = chemo

82
Q

Presents like SCC but comes and goes

flesh colored lesion w/ central crater that contains keratinous material

A

Keratocanthoma

Tx: goes away on it’s own (if not, resect)

83
Q

shiny, pearly appearance w/ telengectasias and rolled edges

A

Basal Cell CA

DX: Punch Bx
TX: Mohs surgery

84
Q 
benign vascular skin tumor 
on lip/oral mucosa 
red, small papule that grows rapidly over wks or months and forms pedunculated or sessile shiny mass 
can occur after trauma
bleeds w/ minor trauma 
common in pregnant pts
A

Pyogenic Granuloma

85
Q

SCC in situ

A

Bowen’s Disease

86
Q

purple lesions on skin (including genitalia, LE, face) in pts w/ HIV and CD4 <100

A

Kaposi’s Sarcoma
(HHV 8)

Tx: antiretroviral therapy

87
Q

silvery scales on extensor surfaces that bleed when scraped off
nail pitting

A

Psoriasis (in adults)

88
Q

Tx for Psoriasis

A

1) Emollients
2) Salicyclic acid to remove collections of scaly material so other therapies can work
3) Mild - Moderate Psoriasis –> localized, topical HIGH POTENCY steroids (0.05% fluocinonide)
4) Severe Plaque Psoriasis (>10% body involved) –> UV light, methotrexate
5) Extensive psoriatic arthritis and psoriasis involving nails –> methotrexate

89
Q

Tx of Facial and Intertriginous Psoriasis

A

Topical tacrolimus

Topical, LOW POTENCY steroids (1% hydrocortisone)

90
Q

What is Guttate Psoriasis? Tx?

A

red, scaly, small teardrop shaped spots

Tx: observation

91
Q

red, itchy plaques of flexor surfaces (“itch that rashes”)
scaly rough areas of thickened skin
↑ IgE

A

Atopic Dermatitis (Eczema) –> onset before age 5

Allergic triad:

  • asthma
  • allergic rhinitis
  • eczema
92
Q

Complication of Eczema

A

superficial skin infxns due to scratching

93
Q

Tx of Eczema

A

Prevent w/ emollients
Active Disease managed w/ topical steroids (eg. triamcinolone) OR antihistamines
Tacrolimus for areas where steroids CI (eg. face, eyelids, flexor surfaces)

94
Q

umbilicated vesicles (superimposed on healing atopic dermatitis lesions)
fever
adenopathy

A

Eczema Herpeticum

–> form of primary HSV infxn (life threatening in infants)

TX: acyclovir

95
Q

dermatitis that involves palms and soles

assoc w/ redness, itching, scaling

A

Dyshidrotic Eczema

96
Q

very itchy patches of eczema on back and LEs

A

Nummular Eczema

97
Q

Dandruff on face
scaly, greasy, flaky skin on red base found on scalp, eyebrows, nasolabial folds, chest, upper back, axilla, inguinal/pubic area

A

Seborrheic Dermatitis

98
Q

Tx of Seborrheic Dermatitis

A 
LOW POTENCY steroids (hydrocortisone) 
Topical antifungal (eg. selenium sulfide, ketoconazole)

Chronic relapsing condition (so need tx every 1-2 wks)

99
Q

thickened, excoriated plaques caused by persistent scratching and rubbing
occurs in areas easy to reach (eg. arms, legs neck)
assoc w/ anxiety disorders

A

Lichen Simplex Chronicus

100
Q

itchy eruption that begins w/ herald patch then disseminates

NO palms/ sole involvement

A

Pityriasis Rosea

TX: self limited

101
Q

facial erythema w/ telengiectasias staring at nose and cheeks
recurrent facial flushing provoked by various stimuli including hot/spicy foods, alcohol, temp extremities, emotional rxns
inflammatory pustules
no comedones
ocular sxs (burning sensation, conjunctivitis, etc)

A

Rosacea

102
Q

Tx of Rosacea

A

Topical metronidazole
PO doxycycline
Severe, refractory cases = isotretinoin
Rhinophyma = laser surgery

103
Q

Tx of Comedonal Acne

A

topical retinoids +/- salicyclic glycolic acid

104
Q

Tx of Inflammatory Acne

A

Mild: topical retinoids + benzoyl peroxide
Moderate: add topical ABXs
Severe: add PO ABXs

105
Q

Tx of Nodular (Cystic) Acne

A

Moderate: topical retinoids + benzoyl peroxide + topical ABXs
Severe: add PO ABXs

106
Q

SEs of Isotretoin

A 
metabolic effects 
--> hyperglycemia, hyperTG (look out for pancreatitis) 
hepatotoxicity 
teratogen 
ocular toxicity 
bld dyscrasias 
mucocutaneous rxns

USMLE Step 3 - ALL (9 decks)

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