Dermatology - Bright Red Rashes

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===Bright Red Rashes===
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*There are five primary players in bright red rashes:
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**Urticaria
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**Erythema multiforme
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**Morbilliform eruptions
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**Lupus erythematosus
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**Dermatomyositis
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====General tendencies====
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*In general, vascular reactions to insult can be described by color, topography, and time course:
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**Color: redness = erythema, results from excessive blood flow
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**Topography: raised lesions result from edmea
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**Time course: a reaction can be described as dynamic = evanescent
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***Note that evanescent means "soon passing out of sight or memory"
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*These three classic vascular reactions ('''erythema, edema, and evanescent''') best describe urticaria, erythema multiforme, and morbilliform reactions
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====Urticaria====
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*Urticaria is an '''allergic reaction''' that results in a bright red rash.
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*Urticaria is colloquially known as "hives"
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**The offending '''antigen is usually from a virus, a food, or a drug'''
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**Physical factors can also induce urticaria (think "SPACE"): sun exposure, pressure, aquagenic, cold, exercise
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*Pathogenesis of urticaria:
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**Induction of immune response results in a dilated (erythema), leaky (edema) vascular state that can be readily changed (evanescent)
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**Urticaria's EEE state is '''primarily driven by histamine''' acting on small dermal vessels
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**'''Purpura can result if''' immune complexes damage endothelium to the extent that '''RBCs escape into the tissue'''
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***Purpura generally lasts more than 24 hours at a single location
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*The rash of urticaria is often described as being '''annular'''.
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*http://www.urticare.com/site/urticare/images/basic_theme/back.gif
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*http://images.paraorkut.com/img/health/images/u/urticaria-1944.jpg
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*http://images.ddccdn.com/enc/images/images/en/hives-urticaria-close-up-1651.jpg
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*http://www.rash-pictures.com/images/4/488.jpg
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====Erythema Multiforme====
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*Erythema multiforme is an '''allergic reaction''' that results in a bright red rash.
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**Note that both urticaria and EM are allergic reactions.
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*Erythema multiforme is distinct from urticaria by its '''immune complexes''' and its '''apoptotic cytotoxic T cells'''.
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*Erythema multiforme is classified as minor and major based on how severe the manifestation.
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**'''EM minor is usually caused by herpes simplex virus''', especially when EM is recurrent.
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**'''EM major is usually caused by drugs'''
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*EM Major has several named causes / syndromes: '''Stevens-Johnson syndrome''' and '''Toxic Epidermal Necrolysis'''
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**Both SJS and TEN are (usually) allergic reactions to drugs that result in necrolysis of keratinocytes of the lower epidermis.
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**Some consider TEN a more severe form or SJS.
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*EM presentation:
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**Target lesions on palsm
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**Oral mucosal involvement
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**http://medicalimages.allrefer.com/large/erythema-multiforme-target-lesions-on-the-palm.jpg
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**http://im.unboundmedicine.com/medicine/ub/image?na=app:16010:ch18_8.bmp
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**http://www.ebmedicine.net/media_library/aboutUs/Erythema%20Multiforme%20Pediactric%20Emergency%20Medicine%20Practice.JPG
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**http://www.dermatopedia.com/wp-content/themes/dermatopedia/dermimages/4774_Erythema_Multiforme.jpg
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**http://www.dermweb.com/hairnailsmucousmembranes/graphics/jpegs/Untitled-8a.jpg
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**http://www.acponline.org/graphics/bioterro/e_minor.jpg
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*Stevens-Johnson Syndrome images:
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**SJS presents with '''widespread "targetoid" lesions'''
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***Note that these targetoid lesions are different than the target lesions in classical EM presentation
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**http://missinglink.ucsf.edu/lm/DermatologyGlossary/img/Dermatology%20Glossary/Glossary%20Clinical%20Images/Stevens_Johnson-28.jpg
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**http://www.nursinghomesabuseblog.com/uploads/image/Picture%2023.png
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**http://rad.usuhs.mil/derm/lecture_notes/Images/Stevens_Johnson.JPG
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**http://img.medscape.com/fullsize/migrated/565/823/edm565823.fig2.jpg
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**http://www.joeway.co.uk/images/stevenjohnsons2.jpg
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=====Target lesions versus Targe''toid'' lesions=====
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*Target lesions:
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**Have '''concentric circles''', especially when there are three concentric circles
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**Have central duskiness or a central blister
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**Have a relatively wide pale circle in between
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**Have an outer, thin, moderately erythematous circle
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**http://www.aic.cuhk.edu.hk/web8/0024_erythema_multiforme.JPG
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**http://dermgunner.com/wp-content/uploads/2010/09/target_lesions_of_erythema_multiforme.jpg
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**http://images.medicinenet.com/images/image_collection/skin/erythema-multiforme-minor.jpg
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**http://drugster.info/img/ail/2957_2979_1.JPG
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**http://drugster.info/img/ail/2957_2979_3.jpg
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**http://www.meddean.luc.edu/lumen/MedEd/medicine/dermatology/melton/erthmul1.jpg
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*Targetoid lesions:
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**Suggest zonality '''but don't have 3 distinct concentric circles'''
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**http://upload.wikimedia.org/wikipedia/commons/thumb/6/68/EMminor09.JPG/230px-EMminor09.JPG
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**http://dermnetnz.org/reactions/img/ermulti1-s.jpg
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**http://dermatology.cdlib.org/1508/articles/2008102101/1.jpg
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====Morbilliform Reactions====
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*Morbilliform reaction is '''through to be a T-cell mediated hypersensitivity''' to drugs or pathogens.
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*Etiology can be drugs or pathogens
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**Many different drugs (including antibiotics) can cause morbilliform reactions
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**Many pathogens can cause morbilliform reactions; usually enterovirus or group A streptococcus
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*One diagnosis the etiology by culturing the "company" kept by the rash
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*Morbilliform reaction manifests same symptoms regardless of causative agent
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*Morbilliform reaction is '''less evanescent''' than multifomre erythema and urticaria
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*Morbilliform reaction is characterized by '''truncal predominance'''
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**Recall that urticaria could show up anywhere and multiform erythema usually involved the oral mucosa and palms of the hands
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*Morbilliform is marked by its '''maculopapular rash'''
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**Recall that a [http://editthis.info/iusmicm/Dermatology_-_Introduction#Macule_.2F_Patch macule] is NOT raised but is discolored and that a [http://editthis.info/iusmicm/Dermatology_-_Introduction#Papule_.2F_Plaque papule] IS raised but not necessarily discolored.
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***http://www.aafp.org/afp/20000815/804_f1.jpg
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***http://eso-cdn.bestpractice.bmj.com/best-practice/images/bp/en-gb/774-2_default.jpg
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=====Viral Exanthems=====
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*Most viral exanthems manifest as ''morbilliform reactions'' ('''except for varicella''').
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**Recall that an exanthem is a skin eruption secondary to systemic disease.
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**Recall that varicella is a viral infection with herpes.
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*Recall the viral agents that cause the classic pediatric exanthems:
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**'''These all cause MORBILLIFORM reactions'''
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**Rubeola (Measles, paramyxovirus infection): cough, coryza, conjunctivitis, koplik spots
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***Rubeola is a systemic infection by paramyxovirus of the genus Morbillivirus
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**Rubella (German Measles, rubella virus infection): 3 day progression, progresses toward cephalocaudal poles
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**Roseola (Roseola Infantum, roseola virus infection): fever, followed with '''rash when "defervesce"'''
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**Mononucleosis: fever, fatigue, (f)pharyngitis, adenopathy, liver / spleen involvement
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**Fifth disease (Erythema infectiosum): slapped cheeks, fishnet erythema, recurrence
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***An example of "multiple stages" seen in many viral exanthems
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*Viral exanthums are characterized by: "dew drop on rose petal" formation, umbilicated vesicles, and multiple stages:
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**http://dermnetnz.org/img/umbilicated-s.jpg
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**http://www.elsevierimages.com/images/vpv/000/000/037/37056-0550x0475.jpg
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**http://203.64.79.70/DERMATOLOGY/fac/img0023.jpg
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====Lupus Erythematous====
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*Lupus erythematous is an autoimmine disease
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*There are three types of lupus: systemic (SLE), discoid (DLE), and subacute cutaneous (SCLE)
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**Systemic and subacute cutaneous can be '''induced by drugs'''
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*'''All three types of SLE are considered ''idiopathic'''''.
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**A genetic predisposition has been demonstrated.
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*SLE (systemic lupus erythematous) requires 4 of 11 ARA criteria be met.
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*DLE (discoid lupus erythematous) is '''primarily cutaneous''' in manifestation.
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*SCLE (subacute cutaneous lupus erythematous); subacute means it is not quite acute or chronic.
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*Pathogenesis of lupus eyrthmatous is though to be '''UV radiation induced'' and involves formation of '''immune complexes'''.
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=====Systemic lupus erythematous=====
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Lupus Erythematosus Background Information
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Defining the spectrum •
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SLE (systemic lupus erythematosus) 4 of 11 ARA criteria
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DLE (discoid lupus erythematosus) primarily cutaneous
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SCLE (subacute cutaneous lupus erythematosus)  Etiology
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Most are idiopathic … genetic susceptibility
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Some are drug-induced (SLE or SCLE)  Pathogenesis
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UV radiation-induced, immune complex disorder
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Systemic Lupus Erythematosus ARA Diagnostic Criteria
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Skin and mucosal criteria  (DUMP)  Discoid lupus  Ulcers (oropharyngeal, usually no pain)  Malar rash  Photosensitivity 
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Systemic criteria  (minimal role of laboratory testing)  Arthritis  CNS (seizures, psychosis)  Serositis (pleural, pericardial)
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  Laboratory abnormalities  Antinuclear antibodies Other serologic tests (dsDNA, anti-Sm)  Hematologic (CBC)  Renal (UA, 24-hour
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urine protein) 
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Lupus Erythematosus – Clinical Features SLE with malar rash, photosensitivity
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Lupus Erythematosus – Clinical Features  SLE with photosensitivity, spillover to unexposed sites
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Lupus Erythematosus – Clinical Features DLE with scarring alopecia, erythema suggesting still active
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Lupus Erythematosus – Clinical Features DLE with erythema, edema, crusting, conchal bowl involvement; with scarring as end
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result
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11
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Dermatomyositis Background Information
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Defining the spectrum •
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Polymyositis (no skin features)
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Dermatomyositis (skin + muscle) both adult and juvenile  Etiology
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Most are idiopathic … genetic susceptibility
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A very small subset are drug-induced  Pathogenesis
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Definite role of UV radiation in disease induction
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Complement membrane attack complex (MAC) has role
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Dermatomyositis Diagnostic Criteria
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Bohan & Peters criteria for diagnosis of dermatomyositis •
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Characteristic skin features
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Proximal muscle weakness  (usually painless)
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Muscle enzyme abnormalties  (CPK, aldolase)
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Characteristic EMG abnormalities
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Muscle biopsy    … currently MRI commonly used to dx muscle disease  **Each of these steps has some degree of limitation; in
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addition, do not need all 5 dx criteria to make diagnosis 
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Dermatomyositis – Clinical Features Heliotrope rash on upper eyelids
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Dermatomyositis – Clinical Features Photosensitivity, tendency towards poikiloderma, “spillover”
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What is “Poikiloderma” ?
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Hyperpigmentation Hypopigmentation Telangiectasias Atrophy  Most commonly seen with … Dermatomyositis UV radiation damage
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Ionizing radiation damage
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Dermatomyositis – Clinical Features Gottron’s papules, periungual telangiectasias
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Dermatomyositis – Clinical Features Gottron’s papules over IP joints, sparing between “knuckles”
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Diagnosis of Cutaneous Drug Reactions Background Information
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Key realities •
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Virtually any inflammatory cutaneous reaction pattern can be drug-induced at times
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Seldom does the clinical appearance alone point to a drug etiology (without aid of additional clinical information)  Higher risk
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drug reaction patterns can either cause …
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Fatal outcome (even if only remotely possible)
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Significant, irreversible morbidity 
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Diagnosis of Cutaneous Drug Reactions Higher Risk Drug Reaction Patterns
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Urticaria / Anaphylaxis  Erythema multiforme major  Stevens-Johnson syndrome  Toxic epidermal necrolysis  Morbilliform reactions
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with “hypersensitivity syndrome”  Vasculitis  … and the rest are relatively low risk (vast majority of rxn)
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Diagnosis of Cutaneous Drug Reactions An Algorithm
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Challenge •
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Timing of drug administration
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Literature reputation
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Personal experience  (… the least important component) Dechallenge
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Response to drug cessation
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Optional – not if essential drug; no help if rxn irreversible Rechallenge
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Gives highest level of certainty of algorithm steps
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Optional – not if higher risk pattern, not if alternative Rx Exclusion  (of non-drug causes of same pattern) 
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  It does not get any better than this …
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  Thank you for  your interest !!
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Current revision as of 08:16, 28 February 2013

R5Wral Say, you got a nice article.Much thanks again.

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