Dermatologic Flashcards
What is required to diagnosis cellulitis?
It’s a clinical diagnosis. Cultures not required because often negative. Should see warmth, swelling, tenderness, erythema in a rapidly-demarkated but rapidly growing area. +/- lymphatic streaking, +/- fever and chills
What is the #1 cause of cellulitis?
staph aureus or group A strep
What is treatment of cellulitis based on?
Largely based on the risk of MRSA infection
What does the skin look like in allergic contact dermatitis? What are differences between this and cellulitis?
Skin: itchy, red, edematous, weepy, crusted, +/- vesicles or bullae
Differences:
- Allergic contact dermatitis is itchy and cellulitis is not
- Cellulitis somestimes has fever, allergic contact dermatitis pretty much never does
How can you distinguish venous stasis dermatitis from cellulitis?
Venous stasis is bilateral, no fever/leukocytosis, and often has hyperpigmentation due to hemosidern deposition.
Also, venous stasis dermatitis usually is painless
Recurrent itchy, red rash on the eyebrows and cheeks. No fever. Diagnosis?
Seborrheic dermatitis. Classically affects the scalp and face because those places have a lot of sebaceous glands. Especially likes eyebrows, eyelids, external auditory canals, nasolabial folds, cheeks.
How do you treat seborrheic dermatitis?
Low potency steroids
Ketoconazole cream
Shampoos with tar, ketoconazole, selenium (scalp)
How is rosacea different from seborrheic dermatitis?
- Rosacea is usually really the cheeks and nose… seborrheic dermatitis can be these areas but also likes eyelids, forehead, ears
- Rosacea has telangectasias, pusutles, papules and seborrheic dermatitis is mostly greasy scales and crusts that itch
BIGGEST DIFFERENCE: Rosacea has pustules
How do you distinguish between rosacea in its early stages (no pustules yet, just facial erythema) and SLE rash?
SLE rash usually spares the nasolabial folds and chin, rosacea does not
What does dermatomyositis look like?
Heliotrope rash: Purple-dusky-red around the eyes
Gottron papules: Elevated, scaly, purple papules and plaques over bony prominences and especially the hands
Also shawl-shaped rash around the shoulders
Groin rash for >1 yr (not itchy) with concomittant scaling on sides of feet. Diagnosis?
Tinea cruris. Definition is that it involves the groin, pubic region, inner thighs
What does tinea cruris look like?
“active” (red) border with central clearing. Localized to genital area (groin, inner thighs)
What does genital candida look like?
Often involves scrotum (unlike tinea cruris). Starts out as pustules then becomes confluent patch with satellite lesions
What can cause SJS?
- Antibiotics (especially TMP/SMX)
- Antiepileptics (like lamictal)
- Allopurinolq
What is erythema multiforme?
Targetoid lesions often involving skin and mucus membranes. 90% associated with infectious (usually HSV), but sometimes drugs or idiopathic. Involves the palms. Often get red papules, vesicles, bullae.
What is erythema migrans?
Hallmark of early lyme disease. Centrifugally spreading ring of erythema that looks like a bulls eye. Starts 3-30 days after tick bite. Usually on the armpit, back of knee, groin, belt line
How do you distinguish erythema multiforme (rash usually associated with HSV) from erythema migrans (rash usually associated with lyme disease)?
- Size (lyme disease/migrans is usually big)
2. Location (lyme disease/migrans usually doesnt involves palms or mucus membranes)
How does RMSF present?
fine, pink, BLANCHING macules and papules on the wrists and ankles that spread both inwards (to torso) and outwards (to palms and soles)
What rashes are associated with strep infection?
- Erythema nodosum (also seen with IBD. On shins)
- Psoriasis flares
- Cellulitis
- Dactylutis
How do you treat shingles (herpes zoster)?
Oral famciclovir *memory: Think of a FAMILY getting shingles
Can also use acyclovir or valcyclovir
How soon do you have to give acyclovir/valcyclovir/famciclovir in order for it to be helpful for shingles?
Within 72 hours of onset of rash
If you do this, it will decrease postherpetic neuralgia, decrease pain, AND accelerate healing
Are steroids used in the treatment of shingles?
Yes. Help accelerate healing, decrease pain, decrease insomina, etc.
But the MAIN treatment is acyclovir/valcyclovir/famcyclovir (oral). Mostly because steroids do NOT improve postherpetic neuralgia
When would you use IV acyclovir instead of oral famciclovir or valacyclovir for treatment of shingles?
- Severe herpes zoster ophthalmicus
- CNS symptoms
Which medications make acne worse?
steroids (testosterone, danazol) corticosteroids isoniazid lithium phenytoin
How do you treat noninflammatory acne (blackheads)?
benzoyl peroxide
salicylic acid
acelaic acid
retinoids
How do you treat mild inflammatory acne (white heads, few papules and pustules)?
topical comedolytic agents
topical antibiotic
When is oral antibiotics first line for acne?
severe inflammatory acne; cystic and pusutlar lesions are extensive
When is isotretinoin first line for acne?
Never. Only indicated for those unresponsive to oral antibiotics.
What are side effects of isotretinoin?
hyperTG
pseudotumor cerebri
decreased BMD
depression and psychosis
What defines acute vs chronic urticaria?
Lasting less vs. more than 24 hours
What % of patients with RMSF have the blanching macules on the wrists?
90%
12 yr old boy back from summer camp with linear rash with excoriations- tx?
Topical steroids. Treat for poison ivy.
How to treat tinea capitis?
Oral griseofulvin
Which fungal infections usually require oral (not topical) antifungal treatment?
scalp infections (tinea capitis) and nail infection (onychomycosis)
What is acral lentiginous melanoma?
Acral lentiginous melanoma is seen more often in dark-skinned people, and typically appears on the palms and soles of feet, including under the nails.
