Dermatology Flashcards
DDx of atopic dermatitis
seborrheic dermatitis, scabies, psoriasis, nutritional deficiencies (zinc), immunodeficiency, cutaneous lymphoma
Which bacteria/viruses can cause superinfection of eczema?
Staph aureus, group A strep, candida, viral (HSV, coxsackie, molluscum)
First-line treatment of atopic dermatitis?
- Bathing 1X per day 5-10 min with lukewarm water (frequency unclear). No oils
- Pat dry, apply steroids then vaseline. Atarax 2-3 times per day for itch
Hydrocortisone 1% ointment
Betamethasone valerate 0.05% ointment for the body
Treatment of scabies?
5% permethrin overnight + repeat 1 week later, treat household contacts, sheets
Apply to entire body in kids < 2 (neck down in kids and adults)
< 8 weeks old: precipitated sulfur in petroleum
Which organism causes “hot tub folliculitis”?
Pseudomonas
Which organism causes furunculosis? Treatment?
MRSA
Tx with I&D, (antibiotics are controversial). Recurrence is common, may need decolonization for MRSA with chlorhexidine washes or intranasal mupirocin
Which organism causes bullous impetigo?
Staph aureus
What is Nikolsky sign? What conditions is it seen in?
skin peeling when rubbed
Seen in SSSS, SJS/TEN
Treatment of SSSS?
Tx with oxacillin or beta lactamase-resistant abx (can use cefazolin), add clindamycin for toxin (+vanco if very unwell for MRSA)
List 5 bacteria that cause soft tissue infection in exposure to water? Which organism causes a bullous infection?
Aeromonas species Edwardsiella tarda Erysipelothrix rhusiopathiae Vibrio vulnificus *BULLOUS Mycobacterium marinum
Which organisms cause tinea capitis?
microsporum canis and trichophyton tonsurans
Treatment of kerion?
terbinafine/griseofulvin and steroids
DDx of hair loss
Tinea capitis/ kerion
Alopecia arreata (no inflammation or scale, hair loss)
Trichotillomania (hairs of different lengths, irregular pattern)
DDx of vesiculobullous rash
- Acquired: Bullous arthropod bites, scabies, drug reaction, friction blisters, burns, dyshidrotic eczema, vasculitis (KD, HSP), frost bite, acropustulosis of infancy
- Congenital: epidermolysis bulla, incontinetia pigmenti, mastocytosis
- Autoimmune: linear IgA disease (chronic bullous disease of childhood), bullous pemphoigoid, SLE, dermatitis herpetiform
DDx of blistering rash
- SJS, TEN, SSSS, VZV, disseminated herpes zoster infection (can also see pneumonia, encephalitis, hepatitis), disseminated HSV infection, sweet syndrome, bullous SLE
- Other generalized blistering disorders: bullous impetigo, bullous pemphigoid, epidermolysis bullosa
List 5 types of drug eruptions
- Urticaria
- “Simple drug reaction” - morbilliform
- Drug hypersensitivity reaction/ DRESS
- Pustular: AGEP (acute generalized exanthematous pustulosis)
- Vesiculobullous - fixed drug eruption, erythema multiforme,. SJS/TEN
Work-up for suspected DRESS
Check echo, eosinophilia, renal/ liver function, thyroid function
Causes of erythema multiforme
- infectious triggers – HSV1/2, mycoplasma
- medications – sulfonamides, abx, antiepileptics
Clinical characteristics and treatment of erythema multiforme?
target lesions (3 zones), often distal extremities. Bullous lesions can rupture. Mucous membrane involvement (1/2 cases), lesions themselves are fixed. Systemic symptoms of fever, malaise, arthralgias are present. Self-limited, lasts 2-3 weeks, stop any offending meds, can treat HSV with acyclovir, antihistamines
Clinical features of SJS/TEN?
SJS < 10%, TEN > 30%
Fever + systemic symptoms – then bullous rash, rupture and desquamation + necrosis.
Nikolsky sign = areas of skin sheer off with gentle pressure.
Involvement of 2+ mucous membranes (oral, ocular, urethral, genital), ocular involvement, scarring. Usually 1-3 weeks after medication.
Treatment of SJS/TEN?
Stop offending meds, wound care – petroleum gauze, analgesia, nutrition, watch for infection. Can use IVIG
How to differentiate EM vs. SJS/TEN vs. SSSS
- Classic targets in EM
- SJS/TEN usually starts on face and trunk, EM on extremities
- EM can involve mucous membranes, but 2+ involved in SJS/TEN
- SSSS affects superficial skin (not full thickness), and no oral mucosal involvement
Manifestations of neonatal lupus
Annular, red, scaly patches. anti-Ro, anti-La. Skin and cardiac (third degree AV block), hematologic (thrombocytopenia, anemia, neutropenia)