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type I HS rxn
- anaphylactic and atopic, antigen cross links igE on pre-sens. mast cells, histamine release
- drug reactions/wheal/asthma
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Type II HS Rxn
- cytotoxic, igM and IgG bind antigen on enemy cell leading to lysis by complement or phagocytosis
- AIHA, erythroblastosis fetalis, goodpasture, rheum fever
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Type III HS rxn
- immune complex: antigen ab complexes activate complement, pmns come and release lysosomal enzymes
- SLE, RA
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Serum sickness
antibodies to foreign proteins are produced in ~5 days, immune complexes form and are deposited in membrane where they fix complement and cause damage, most caused by drugs no serum
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Type 4 HS rxn
- sensitized t lympho encounter antigen and release lymphokinse leading to macrophage activation, delayed, cell mediated not antibody mediated
- Tb skin test, contact derm, transplant rejection
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SJS/TEN
- dont confuse with SSSS (kids, <6)
- Drug causes: phenytoin, carbamazepine, quinolones, cephalosporins, allopurinol, cst, nsaids
- SJS: degen of basal layer of epidermis
- TEN: full thickness eosinophilic epidermal necrosis
- SJS <10%, TEN >30%
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Bullous pemphigoid vs pemphigus vulgaris
- B.P: blisters at BM, not in mouth, neg nikolsky, >60 yo, rare mortality, less severe, rx: cst
- P.V. blisters intraepidermal, anti desmoglein Ab, +nikolsky, in mouth, 40-60, assoc with ace, penicillamine, phenobarb, penicillin
- prednisone+IvIG, rituximab
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Molluscum contagiosum
- young kids, HIV or dec cellular immunity
- Waxy papules with central umbil
- Dx by clinical, confirm by looking for inclusion/molluscum bodies
- Rx: can do local destruction via freezing etc
- Resolve spontaneously
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Ludwigs angina
- bilateral cellulitis of submental/submaxillary and sublingual spaces, results from infected tooth
- sx: dysphagia, fever, drooling, red warm mouth can lead to death from asphyx.
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SCC
- AKs are precursirm crusting and ulceration, arsenic can cause multi SCC in palmoplantar distribution
- rx: excise
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BSC
- smooth, pearly, rolled edges
- MC cancer, slow growing ,no met potential
- excision, etc.
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Bacillary angiomatosis
- baronella hensalae, mimics kaposi, must be excluded in KS patients
- Rx: erythromycin
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Mycosis fungoides
- cut T cell lymphoma
- not a fungus, slow progressive neoplastic prolif of T cells
- psoriatic appearing plaque that is palpable and possibly pruritic, likes butt
- internal organs can be involved
- sezary syn: leukemic phase
- Dx: cerebriform lymphocytes
- Rx: photothereapy
- leonine facies
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