Dermatology Flashcards
Erythema Toxicum Neonatorium
1-3 after delivery - looks like eczema - red papules, pustules and vesicles w/ red halos. Eosinophils are present in the pustules or vesicles. Goes away in 1-2 weeks on its own.
Type 1 Hypersensitivity
Anaphylactic and atopic. - Ag cross-links IgE on mast cells and basophils and histamine is released triggering PREFORMED ABs.
This is real fast.
Type 2 Hypersensitivity
Cytotoxic. - IgM and IgG bind to Ag enemy cells and the enemy cells then get lysed by COMPLEMENT (MAC) or PHAGOCYTOSIS
ex: autoimmune hemolytic anemia, goodpastures, rheumatic fever
Type 3 Hypersensitivity
Immune complex mediated - Ag-Ab-Comp, which attract PMNs to come kill by releasing enzymes.
ex: glomerulonephritis, vasculitis, SLE, RA, serum sickness, arthus reaction
Type 4 Hypersensitivity
Delayed (T cell mediated) - T-cells sense Ags and release lymphokines and kill via Macrophage activation. NOT TRANSFERABLE BY SERUM AS THIS IS NOT AB MEDIATED
ex: TB skin tests, transplant rejections, contact dermatitis
An infant with a hx of eczema treated with CTSDs is brought in fora new onset of rash and fever. Physical exam shows grouped vesicles involving eczematous areas of extremities and face. What to do?
This is an emergency. It is eczema herpeticum. HSV can spread systemically to the brain
Tx: start IV acyclovir
What bacterial and viral infections are people with eczema (atopic dermatitis) more susceptible to?
bacteria - S.A.
viral - HSV or Molluscum
What disease does Pityrosporum ovale cause?
seborrheic dermatitis
Adult with seborrheic dermatitis…
think HIV
How long does it take for a medication to cause a derm reaction?
7 days. So if the pt starts a new drug and gets a rash 2 days later, its probably not the drugs fault.
Erythema Multiforme
Cutaneous reaction that starts as red macules and turn into pale centered TARGETS. Often triggered by HSV (lips,) drugs, or mycoplasmal infections. The mucous membranes, palms and soles can all be affected. can lead to TENS or SJS
Tx: antipuritics, if major you should treat them like burns. steroids do nothing.
which is worse, TEN or SJS?
SJS, it involves >30% BSA, and TEN only involves
PATHOLOGY of SJS and TEN:
SJS: degeneration of basal layer of epidermis
TEN: Full thickness eosinophilic epidermal necrosis
Erythema Nodosum
Inflammation of SQ fat tissue caused by strep, coccioioides, yersinia, TB, or drugs (sulfa, ABs, OCPs) or sarcoid, crohns, UC, behcets
Painful red nodules in pretibial area, have joint pain. MAY HAVE FALSE +VDRL (sle pts)
Dermatitis Herpetiformis (DH)
Is not caused by herpes, it is what celiac pts get. It has pruritic papules and vesicles on the elbows, knees, butt, neck, scalp.
Tx: dapsone, quit gluten.