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DERMATOLOGY (Hypersensitivity Dermatitis eczema psoriasis (psoriasis…

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        Clinical Case
        
        Notes:
        
        note that
      - *Posion Ivy Dermatitis
        
        Case presentation:
        
        Notes:
        
        note that Poison Ivy Dermatitis is a type 4 hypersensitivity reaction
        --> think that it usually takes a few days for poison ivy dermatitis to actually appear
- - - - Clinical cases
        
        Clinical case
        
        Case presentation:
        
        Notes:
        
        3 major bacteria that can cause skin diseases are:
        --> staph aereus
        --> Group A strept. (strep pyogenes)
        --> pseudamonas Aeruginosa
        
        key differential between these 3 and what defines impetigo is whether the rash on the skin is erythematous and whether there is yellow honey crust over the rash
        --> staph aereus or Group A strept.
        
        pseudamonas Aeruginosa causes things like hot tub folliculitis and ecthyma gangrenosum
        --> key is that pseudamonas aeruginosa does NOT have yellow honey crust with it
        
        note that staph. epidermidis is a normal skin flora bacteria so NEVER causes skin disease.
        --> it can however cause opportunistic infections and things like artificial heart valve infections and UTIs from catheders
  - - - Clinical cases
        
        Clinical Case
        
        Clinical Case
        
        Notes:
        
        note that
        
        Appearance and presentation:
        
        scales and crusting
        
        erythamatous plaques
        
        highly pruritic due to delayed = type 4 hypersensitivity Rxn to the feces and eggs
        
        HIV patients
        
        Scabies internal organs, eggs and spine can be seen on histopathology
        
        HIV and Crusted Scabies:
        
        since HIV patients are immunosupressed, they CANNOT mount a delayed = type 4 hypersensitivity Rxn to the feces and eggs
        
        thus they don't get the pruritic rash that normal people get
        --> but they get millions of mites proliferating and the infection gets out of control if not treated
        
        HIV Scabies are highly CRUSTED --> seen on left
        
        Treatment
        
        topical permethrin
        --> block voltage gated Na+ channels in invertebrates
        
        oral ivermectin
        --> block voltage gated Cl- channels in invertebrates
        --> more serioous infections like in HIV, to be used in addition to permethrin
        
        think SCABIES like SALT
        --> blocking SALT from the mites (Na and Cl channels)
        --> you also need to PERMANENTLY THIN the epidermis layer (where they burrow)
        = Permethrin
- - - - common maculopapular rashes in Kids
        
        VZV for instance
- - - - *Acne
        
        Clinical Cases
        
        Clinical Case
        
        Clinical Case
        
        Notes:
        
        note that
        
        Puberty Androgen Surge:
        
        note always consider in young athletic men that they may be taking anabolic steroids that cause acne
        
        DHT = dihydrotestosterone is one of the main factors that can increase acne
        --> increase follicular proliferation and
        --> excessive sebum production
        
        Clinical Cases
        
        Clinical Case
        
        Clinical Case
        
        Notes:
        
        note that
        
        Tx of acne
        
        retinoic acid = vitamin A
        
        abx =
        
        goal of acne treatment =
        
        Clinical Cases
        
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        Clinical Case
        
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        Xeroderma Pigmentosum
        
        see dermatology
        
        Xeroderma Pigmentosum example
        
        Clinical Case
        
        Notes:
        
        note that although Xeroderma pigmentosum itself is not a malignancy, it normally leads to cancer by age 5
        
        xeroderma pigmentosum is autosomal recessive
        
        due to genetic defect in excision repair
        
        they present with normal skin at birth, but after their first sun exposure thy burn very easy
        
        they then develop hypo and hyper pigmented areas of skin due to UV damage
        
        after 5 years of age they usually get melanoma, SSC or BCC malignancies
        
        Xeroderma Pigmentosum example 2
        
        Clinical Case
        
        Notes:
        
        note that Xeroderma pigmentosum is a genetic defect in DNA repair enzymes
        
        they are succeptible to UV damage to DNA and cannot repair this
        
        UV damage to DNA causes T-dimers = Thymine dimers
        --> where adjacent thymine attach to each other
        
        T-dimers are repaired by ENDONUCLEASE enzymes
        --> think the T-dimers are inside = endo the DNA chain and only need to be openned and repaired at that specific place
        --> Endonuclease
        
        they are then replaced with new bases = DNA POL
        
        zipped back up = DNA ligase = ligase glue