Urticaria
Module Instructions
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Urticaria: Basic Facts
Urticaria is a vascular reaction of the skin and appears as wheals surrounded by a red halo or flare. Cardinal symptom is PRURITUS As high as 15-25% of the population experience urticaria, of these 40% have urticaria, 10% have angioedema, 50% have both Angioedema is caused by swelling of subcutaneous tissue whereas urticaria is caused by swelling of the dermis Both angioedema and urticaria can result in respiratory compromise and hypotension Angioedema and/or urticaria may be the cutaneous presentation of anaphylaxis, so assessment of the respiratory and cardiovascular systems is vital!
Urticaria: Basic Facts
Urticaria can evolve over days-weeks or after a number of minutes. Individual wheals rarely last >12hrs Urticaria can be immunologic (IgE dependent, type 1 hypersensitivity or complement mediated), non-immunologic (direct or indirect mast cell degranulation), or idiopathic (more than 50% of cases)
Uticaria: Basic Facts
Urticaria can be acute or chronic, chronic urticaria lasts >6wks >50% of chronic urticaria is idiopathic. 7-17% are caused by physical stimuli such as exercise, sun, temperature changes, and pressure (the physical urticarias) Physical urticarias are confirmed by challenge test with the respective trigger. Normally the urticarial lesions resolve very quickly after the physical stimuli is removed i.e. 24hrs, so unlikely) b. erythema multiforme minor c. poison ivy/oak (causes contact dermatitis with vesicles and it is not targetoid) d. psoriasis (see psoriasis module) e. atopic dermatitis (see atopic dermatitis module)
Erythema Multiforme (EM)
Erythema multiforme minor as in this case is also know as herpes simplex-associated erythema multiforme (HAEM) Typically, the disease is self-limited and recurrent during the spring and fall in young adults
Seasonal variation is due to the fact that orolabial herpes is triggered by sunlight exposure. Therefore, sunlight triggers HSV which triggers EM.
Erythema Multiforme on Exam
The lesions begin as erythematous macules and progress to papules over 1-2 days The central area can become flat or form a vesicle Typically the areas of involvement are acral, and involvement of palms and soles is characteristic Mucous membrane involvement, especially of the oral mucosa can occur (usually involving only one mucous membrane)
CASE 4
Case 4: History
HPI: 65 yo M presents with diffuse rash and blistering and crusting of the lips. He has had a cough last week and has had a fever for the past 3 days. PMH: none All: none Meds: started on bactrim for presumed pneumonia last week FH: non-remarkable SH: non-remarkable ROS: +fever, +fatigue
Case 4: Exam Gen: toxic appearing, +lymphadenopathy Skin: diffuse purpuric macules coalescing into patches, some with central blistering localized to chest, arms and palms. Hemorrhagic crusting of the lips
Case 4: Question 1
What is the most likely diagnosis? a. erythema multiforme minor b. Stevens-Johnson syndrome c. disseminated HSV d. bullous pemphigoid
Case 4: Question 1 Answer: b What is the most likely diagnosis? a. erythema multiforme minor (we would have expected more acral involvement and less mucous membrane involvement) b. Stevens-Johnson syndrome c. disseminated HSV (would expect more grouped vesicles on the body) d. bullous pemphigoid (would not expect such an acute, severe presentation)
Stevens-Johnson Syndrome
Steven Johnson’s Syndrome primarily affects at least 2 MM and involves 30% BSA involvement 10-30% BSA involvement is considered SJS/TEN overlap
Stevens-Johnson Syndrome
Typically have an accompanying fever and possibly prodromal URI Distribution is more diffuse and lesions are more confluent than in erythema multiforme minor. Lesions begin on the face and trunk and often appear as purpuric macules with central blistering 2+ mucous membranes are involved
Stevens-Johnson Syndrome
In adults, typically caused by medications including sulfonamides, antibiotics, NSAIDs, allopurinol, and anticonvulsants In children, Mycoplasma pneumoniae is also a common cause Radiation therapy of malignancy may also trigger SJS
Complications
Most common complication of EM/SJS is VISUAL LOSS due to corneal scarring from the MM involvement TEN is associated with significant mortality (515%)
Factors associated with worse outcome are age, how long offending medication is continued, HIV status, and BSA of involvement
Treatment in EM Minor EM minor is often self-limited in children and resolves within 2-6 weeks In herpes associated cases, antivirals can be used as prophylactically and will prevent recurrence in 50% of cases
Treatment in SJS
In SJS, secondary infection is a possibility given skin loss and therefore antibiotics should be given In cases of >10-30% skin involvement, the patient should be placed in a burn unit and IVIg is considered In severe cases, biopsy is ALWAYS done to confirm the diagnosis and it is the only dermatologic condition where a frozen section is done
END OF MODULE
