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.
Bullous Pemphigoid vs. Pemphigus Vulgaris
BP: basement membrane disease - w/ no nikolsky’s sign and NO MUCOSA. usually pts >60yo, milder course and tx w/ steroids
PV: Intraepidermal disease w/ nikolsky’s sign and MUCOSA. pts 40-60yo, tx w/ steroids and IVIG.
What are considered “Aids defining illnesses?”
Asymptomatic HSV lasting longer than 1m (look for multinucleated giant cells on pathology)
Candida infections
Molluscum Contagiosum in a 25yo sexually active male?
They look like waxy umbilicatios papules (look for large inclusion bodies on pathology)
be concerned for AIDS
What to be concerned for in babies of mothers with HPV active on genitals?
Laryngeal wart transmission via aspiration
What bacteria causes Impetigo?
GAS (can cause acute strep glomerulonephritis)
SA (will cause bullous type)
Both can cause erysipelas (a cheek rash that you tx w/ PEN)
Kid comes in with a rash on his face that looks like “sunburn w/ goosebumps” - he had had URI symptoms for 3 weeks prior. What is his Dx?
He has scarlet fever. Caused by Strep Pyogenes
Tx w/ PEN
Kid comes in with small “rose spots” rash on the trunk in groups of 10-20. Also has a fever. What is the organism?
Salmonella Typhi
There can be some GI involvement.
Tx: FQ or 3rd gen Ceph. Cholecystectomy if a chronic carrier
What is the most common cause of nec fascitis?
Mixed infection (SA, ecoli, c.perf) or pure S. Pyogenes
Tx: PEN or clinda if it is strep. If anaerobic, tx w/ metro of 3rd gen ceph
What is the line of tx for acne?
- Topical tretinoin (Retin-A)
- Benzoyl Peroxide
- Abx
- Isoretonin (is a teratogen, and causes hi LFTs, Cholesterol, TGs, and depression.)
What does Tinea Versicolor look like on pathology?
spaghetti and meatballs on KOH stain
Normal yeast is the cause (malassezia furfur) and tx w/ ketoconazole or zinc shampoo
Kid comes in with scaly, pruritic eruption w/ central clearing on his trunk. Dx?
Tinea Corporis. Common in kids w/ pets or immunocompromised. Dx w/ KOH prep
Why do crab bites turn blue? Tx?
They have anticoagulant in them
Tx: Pyrethrin or Permethrin
Kid comes in with small macules in between his knuckles. Kid is dirty. Dx? Tx?
Scabies.
Tx: Permethrin 5% all over or PO Ivermectin
Dry vs Wet vs Gas Gangrene
Dry: due to atherosclerosis and insufficient blood flow
Wet: caused by bacterial infections
Gas: caused by c. perfringens - this is a medical emergency (tx w/ debridement or hyperbaric O2)
Woman comes in with violaceous, flat topped polygonal papules on her genetalia. Dx? Tx?
Lichen Planus. Associated with HPV
Tx: topical steroids/systemic steroids
Old woman w/ red patches on cheeks. Dx/Tx?
Rosacea. Tx = metro
Man comes in w/ rash that started as a herald patch and spread all over his back in a christmas tree pattern. Looks like cigarette paper. Dx/Tx?
Pityriasis Rosea. Associated w/ HHV6 or 7
Dx w/ KOH and r/o syphilis w/ RPR
Is Vitiligo due to decreased function or lack of melanocytes?
Absence of melanocytes
What chemical exposure is associated with SqCC?
Arsenic exposure
How are melanomas staged (depth vs. spread?)
Depth/thickness of invasion. Also by TNM (Tumor-node-metastasis system)
What is the most common HIV associated malignancy?
Kaposi’s sarcoma
Man comes in with what looks like psoriasis rash on his butt. He also has palpable nodes w/ brown nodules. dx? Tx? Worst fear?
Dx = Mycosis Fungoides (a cutaneous T-Cell lymphoma)
Tx: phototherapy
Worst fear: Can involve organs (liver/spleen) and also cause a LEONINE FACIES
