This presentation provides guidelines for systematically evaluating and diagnosing unknown rashes seen in the emergency department setting. [1] The speaker outlines a structured approach involving obtaining a thorough history, performing a focused physical exam describing the rash characteristics, and utilizing diagnostic algorithms to establish a differential diagnosis based on lesion type, distribution, and associated symptoms. [2] Key considerations include differentiating potentially life-threatening conditions requiring emergent interventions from self-limiting disorders. [3] Through a systematic approach, the unknown rash can often be narrowed down to one or two likely diagnoses to guide appropriate treatment and disposition.

1. (+)Heather M. Murphy-Lavoie, MD
Assistant Residency Director and
Assistant Professor, Louisiana State
University, Section of Emergency
Medicine, New Orleans, Louisiana
Approach to the Unknown Rash
How do you approach the unknown rash? Knowing how to
identify and classify a skin lesion is an essential component
in developing a systematic and organized approach to any
lesion. The speaker will present guidelines for the proper
diagnosis of various dermatologic conditions using case
presentations to illustrate these concepts.
• Describe dermatologic conditions by the type of lesion
and the distribution area.
• Develop a systematic approach to skin lesions.
• Identify dermatologic conditions requiring emergency
interventions.
• Discuss appropriate differential diagnoses, treatments,
and dispositions for patients with dermatologic
complaints.
TH-267
Thursday, October 8, 2009
9:00 AM - 9:50 AM
Boston Convention & Exhibition Center
(+)No significant financial relationships to disclose

2. Approach To The Unknown Rash
By Heather Murphy-Lavoie, MD
I. Introduction
a. There are more than 3000 dermatologic diagnoses
b. Approximately 5% of ED visits are for a dermatologic
complaint
c. Objectives
i. Describe dermatologic conditions by the type of lesion
and the distribution area.
ii. Develop a systematic approach to skin lesions.
iii. Identify dermatologic conditions requiring emergency
interventions.
iv. Discuss appropriate differential diagnoses, treatments,
and dispositions for patients with dermatologic
complaints.
II. History
a. Age
b. Duration
c. Associated symptoms
i. Itching
ii. Fever
iii. Pain
d. Travel/Location
e. Sick Contacts
f. Past Medical History
g. Medications – new
h. Menstrual history
i. Sexual history
j. Vaccinations
III. Physical Exam
a. Vital signs
i. Hypotension
ii. Tachycardia
iii. Fever
iv. Mental Status Change
b. Distribution

3. i. Central
ii. Peripheral
iii. Flexural surfaces
iv. Intertriginous
v. Dermatomal
vi. Neurotic Excoriation
vii. Extensor surfaces
viii. Mucosal surface involvement
c. Appearance
i. Scaly/Moist
ii. Color
iii. Hyper/hypopigmented
iv. Honey Crusted
v. Umbilicated
vi. Blanching
vii. Palpable
d. Wood’s Lamp
i. Microsporum Tinea Capitus (green)
ii. Erythrasma (coral red)
IV. Algorithms
a. Erythematous
b. Maculopapular
c. Petechiae/Purpura
d. Vesiculo-bullous

4. ALGORITHM ERYTHEMATOUS RASH
ERYTHEMATOUS RASH
NIKOLSKY’S SIGN
YES
NO
FEBRILE AFEBRILE
Staph SSS TEN (adult)
(child) FEBRILE AFEBRILE
TEN (adult)
Toxic Shock (mucous Anaphylaxis
membranes) Scombroid
Kawasaki Syndrome (child, Alcohol Flush
hands)
Scarlet Fever (sand paper)
Differential Diagnosis:
Staph SSS = Staphylococcal Scaled Skin Syndrome - children, IV Penicillinase-
resistant penicillin, IV Fluids, local wound care
Toxic Shock Synd= Toxic Shock Syndrome - look for source (eg. a tampon) and
remove, IV Penicillinase-resistant penicillin, IV fluids, supportive care, hospital
admission
Kawasaki= Kawasaki’s Disease - children, mucous membranes, lymph nodes, hands
and feet, elevated platelet count, treat with immune globulin, aspirin
Scarlet Fever - children, sandpaper-like rash, strawberry tongue, tonsillitis, treat
with penicillin
TEN = Toxic Epidermal Necrolysis - adults, drug reaction- often sulfa, treatment
remove offending source, wound care, IV fluids, admit to burn center
Anaphylaxis - treat with steroids, antihistamines, H2 blockers and possibly
epinephrine for the most severe cases
Scombroid - history of eating fish recently, treat with antihistamines, usually self-
limited
Alcohol flushing - history of alcohol ingestion, prior episodes, no itching, normal
vitals, no fever, self-limited

5. ALGORITHM MACULOPAPULAR RASH
MACULOPAPULAR RASH
CENTRAL PERIPHERAL
DISTRIBUTION DISTRIBUTION
FEVER / ILL? FEVER / ILL?
YES NO YES NO
Viral Exanthem Drug Reaction TARGET LESION
Lyme Disease Pityriasis LESIONS DISTRIBUTION
(erythema migrans) (herald patch)
YES NO FLEXO EXTENSOR
Stevens-Johnson Meningococcemia Scabies Psoriasis
TEN Rocky Mountain Eczema
Erythema Multiforme Spotted Fever
Syphilis
Lyme Disease
(erythema migrans)
Viral Exanthem - Measles, Rubella, Fifths, etc, self-limiting, supportive care
Lyme Disease - Tick bite, erythema migrans, arthralgias, headache, doxycycline
Pityriasis - scaly lesions, herald patch, Christmas tree pattern, treatment includes:
UV light, moisturizing lotion, Aveeno, antihistamines
Drug Reaction - remove the drug, symptomatic treatment
Stevens-Johnson Syndrome - mucosal involvement, remove drug/treat illness,
supportive therapy, hospital admission
EM = Erythema Multiforme - treat illness/stop drug, supportive care, topical
steroids and outpatient follow-up for minor cases
Meningiococcemia - ill appearing, mental status change, lumbar puncture,
ceftriaxone, isolation, treat close contacts, hospital admission
RMSF = Rocky Mountain Spotted Fever - tick bite, endemic area, headache,
arthralgias, doxycycline
Scabies - excoriated burrows, itches worse at night, permethrin

6. ALGORITHM VESICULO-BULLOUS RASH
VESICULO-BULLOUS RASH
FEBRILE AFEBRILE
DIFFUSE LOCALIZED DIFFUSE LOCALIZED
DISTRIBUTION DISTRIBUTION DISTRIBUTION DISTRIBUTION
Varicella / Chicken Pox Necrotizing Fasciitis Bullous Pemphigus Contact Dermatitis
Small Pox Hand Foot Mouth Pemphigus Vulgaris Herpes Zoster
Disseminated GC Dyshidrotic Eczema
Purpurpa Fulminans / DIC Burns
Differential Diagnosis:
Varicella/Chicken Pox – excoriated lesions in multiple stages, starts centrally,
isolate, rare hospitalization, symptomatic treatment, antipyretics (not Aspirin)
Small Pox – all lesions in one stage, more peripheral distribution, isolate, notify
office of public health and CDC
Disseminated GC= Gonococcemia - purple vesicles, sparce, peripheral, associated
urethritis/cervicitis/septic arthritis, ceftriaxone
Purpura Fulminans/DIC = Disseminated Intervascular Coagulation - treat the
underlying cause, fresh frozen plasma, platelet transfusions, ICU admission
Necrotizing Fasciitis – surgical emergency, debridement, IV anti-streptococcal
broad spectrum antibiotic, hyperbaric oxygen therapy
Hand, Foot and Mouth Disease – children, vesicles on palms, soles and in mouth,
self-limited, symptomatic treatment
Bullous Pemphigus -chronic autoimmune blistering, elderly, usually benign,
steroids
Pemphigus Vulgaris – mucous membrane involvement, much higher mortality than
Bullous Pemphigus, steroids, admission
Zoster – acyclovir, analgesia, steroids
Contact Dermatits - symptomatic treatment, long taper of steroids for severe cases
Dyshidrotic Eczema - topical steroids

7. ALGORITHM PETECHIAL/PURPURIC RASH
PETECHIAL / PURPURIC RASH
FEBRILE & TOXIC AFEBRILE & NON-TOXIC
PALPABLE NOT PALPABLE PALPABLE NOT PALPABLE
Meningococcemia Purpurpa Fulminans / DIC Cutaneous ITP
Disseminated GC TTP Vasculitis
Endocarditis
RMSF
HSP
Differential Diagnosis:
Meningiococcemia - ill appearing, mental status change, lumbar puncture,
ceftriaxone, isolation, treat close contacts, admission
Disseminated GC= Gonococcemia - purple vesicles, sparce, peripheral, associated
urethritis/cervicitis/septic arthritis, ceftriaxone
Endocarditis – new murmur, vegetations on valves, positive blood cultures, IV
vancomycin and gentamicin pending culture results
RMSF = Rocky Mountain Spotted Fever - tick bite, endemic area, headache,
arthralgias, doxycycline
HSP = Henoch Schonlein Purpura – children, associated arthralgias, hematuria and
GI symptoms, supportive therapy
TTP= Thrombotic Thrombocytopenic Purpura - low platelet count, ICU admission,
treat underlying cause, plasmapheresis, splenectomy, selective transfusion, NO
platelets
Vasculitis – treat the underlying process if possible, may require steroids and/or
other anti-inflammatory agents
ITP – Idiopathic Thrombocytopenic Purpura - transfuse platelets if bleeding or less
than 5000/mm3 – 10000/mm3, emergent Hematology consultation

8. V. Summary
With the type of lesion, distribution, and whether or not the
patient is ill, one can narrow the diagnosis down to one or two
diagnoses in many cases.
THE VERY YOUNG THE VERY OLD
Staph SSS, Kawasaki’s disease, pemphigus vulgaris, sepsis, TEN, SJS
viral exanthem, meningococcemia
TOXIC IMMUNOSUPPRESSED
necrotizing fasciitis, meningococcemia, necrotizing fasciitis, meningococcemia,
TEN, SJS, TSS, RMSF, TTP endocarditis, herpes zoster, sepsis
DIFFUSE ERYTHEMA PETECHIAE / PURPURA
staph SSS, staph TSS, strep TSS, meningococcemia, endocarditis, TTP, ITP
TEN vasculitis, DIC, RMSF
MUCOSAL LESIONS HYPOTENSION
EM major, TEN, SJS, meningococcemia, TTP,
pemphigus vulgaris TSS, RMSF, TEN, SJS
TEN = toxic epidermal necrolysis; SJS = Stevens-Johnson Syndrome, TSS = toxic shock
syndrome, RMSF = Rocky Mountain spotted fever, SSS = scalded skin syndrome, DIC =
disseminated intravascular coagulopathy, EM = erythema multiforme, TTP= thrombotic
thrombocytopenic purpura
VI. Appendix
LESION single small RASH more extensive
diseased area involvement
MACULE circumscribed area of change PUSTULE circumscribed area
without elevation containing purulence
PAPULE solid raised lesion < 0.5 cm VESICLE circumscribed fluid-filled
area < 0.5 cm
NODULE solid raised lesion > 0.5 cm BULLA circumscribed fluid-filled
area > 0.5 cm
PLAQUE circumscribed elevated PETECHIAE small red / brown macules
confluence of papules > 0.5 cm < 0.5 cm that do not blanche

9. a. More Definitions
i. Erosion- loss of epidermis only
ii. Ulcer- extends below epidermis to involve dermis and subcutaneous
tissue
iii. Fissure- linear split in skin
iv. Excoriation- linear superficial erosions or crusts due to scratching
v. Wheal- soft smooth, raised papule, light pink (eg. Urticaria)
vi. Burrow- linear “S” shaped papule 3-5mm long
vii. Purpura- > 0.5cm does not blanch with pressure, red/purple macules
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11. UNKNOWN RASH SELF-ASSESMENT
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