Cutaneous Reaction Patterns

Question 1

What is Urticaria? What kind of hypersensitivity reaction is it?

Answer 1

aka hives

• pink edematous papules and plaques that occur on the skin
• migratory lesions and individual lesions last <24 hrs but urticaria may last longer
• Caused by IgE mediated immediate hypersensitivity (type I)

Question 2

Most cases of Urticaria are ______ but the most common identifie cause is _______. What is the treatment?

Answer 2

Most cases of urticaria are idiopathic, but most common identified cause is upper respiratory infection, drugs cause 10%

treat w antihistamines

Nonsedating (loratadine, cetirizine, fexofenadine)

Sedating (diphenhydramine, hydroxyzine)

Question 3

What is the most common cutaneous drug eruption?

Answer 3

Exanthematous drug eruption also called morbilliform drug dreaction (remember morbilliform rash means maculopapular like measles)

Question 4

What kind of hypersensitivity reaction is an Exanthematous Drug Eruption? What is the process of reaction development?

Answer 4

• Delayed Type IV hypersensitivity
• Monomorphic macules and thin papules start on the face and trunk, then spread to the extremities.
• lesions are pruritic an low-grade fever may be present, but reaction is limited to skin

Question 5

What is the onset for an Exanthematous Drug Reaction? What is treatment?

Answer 5

• onset is 2-14 days after drug initiation, even if the drug has already been discontinued.
• resolves in 1-2 weeks, even with continuation of culprit drug if necessary. treatment is supportive for pruritus with topical corticosteroids and oral antihistamines.

Question 6

Do you need to discontinue the drug to treat an Exanthematous Drug Reaction?

Answer 6

No

Question 7

What is seen with a Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)?

Answer 7

• cutaneous eruption resembles exanthematous drug reaction, but involves fever, facial edema, enlarged lymph nodes, and arthralgias.
• eosinophilia can occur but not always
• liver involvement via elevation of hepatic enzymes
• myocarditis, pneumonitis, nephritis, thyroiditis, brain involvement

Question 8

What is the most common location of systemic involvemnt in DRESS

Answer 8

Liver!!

Question 9

Do you need to discontinue the causal drug in a DRESS reaction?

Answer 9

fatal in 10% of cases, so prompt recognition and discontinuation of suspected drug cause is imperative. treat with corticosteroids

Question 10

What is seen during Erythema Multiforme?

Answer 10

• Target lesions characterized by 3 or more color zones and dusky red or purple center.
• arise abruptly on acral areas: hands, feet, elbows, and knees and last up to 2 weeks
• involement of ocular, oral and genital mucosa sometimes seen

Question 11

Wat causes most cases of EM?

Answer 11

Infectious triggers (Herpes Simplex Virus) are responsible for 90% and drugs cause 10%

Question 12

How do you treat EM?

Answer 12

self-resolves in a few weeks, symptomatic treatment for pruritis and pain is suficient, and systemic corticosteroids may be considered for severe disease

Question 13

What precedes Stevens-Johnson syndrome (SJS), Toxic Epidermal Necrolysis (TEN) and SJS/TEN?

Answer 13

a prodrome of fever, mailaise and upper respiratory symptoms before the onset of cutaneous lesions

Question 14

What happens after the prodrome in SJS/TEN?

Answer 14

• painful red patches evolve rapidly into bullae and areas of necrosis.
• epidermal detachment
• any mucosal surface includin oral, conjuctiva, genital and GI mucosae may be involved

Question 15

WHat is the difference in epidermal detachment between SJS, TEN and SJS/TEN?

Answer 15

SJS: <10% of body surface area

SJS/TEN: 10-30% detachment

TEN: over 30% body surface involvement

Question 16

What are the most common drugs implicated?

Answer 16

allopurinol, NSAIDS, sulf drugs, anticonvulsants (lamotrigene, carbamazepine, phenobarbital, phenytoin) and antibiotics

Question 17

How do we treat SJS/TEN?

Answer 17

mortality rate for severe TEN is 35% usually from sepsis. so you need to discontinue the drug PROMPTLY. suportive multidisciplinary care for these sick patients is important, while the use of IV immunoglobin is controversial

Question 18

What is Vasculitis?

Answer 18

inflammation and destruction of blood vessels, either arteries or veins.

Question 19

What is Leukocytoclastic Vasculitis? (LCV)

Answer 19

• histologic diagnosis associated with multiple clinical presentations
• term given to small vessel vasculitis of skin when neutrophils are predominant inflammatory cell seen on biopsy
  *

Question 20

What are the common causes of LCV?

Answer 20

• 50% are idiopathic
• infections (upper respiratory, group A strep, hepatitis B, C, HIV) and drug hypersensitivites (most commonly antibiotics)

Question 21

What is the hallmark for LCV?

Answer 21

• palpable purpura typically on the legs
• urticarial lesions may be found but are fixed for over 24 hours
• other possible findings include: nodules, ulceration, and livedo reticularis (purple, lacy, net-like pattern)

Question 22

What is Henoch-Schonlein Purpura? (HSP) How do you treat it?

Answer 22

• small vessel vasculitis that predominately affects children
• palpable purpura on the skin, especially on the buttocks and lower extremities are the main physical finding
• arthritis, abdominal pain, GI bleeding and nephritis may be present in some cases
• self-limited and resolves over the course of 2-4 weeks

Question 23

What are common triggers of HSP?

Answer 23

• infections, typically group A streptococcal infection and other upper respiratory infections

Question 24

What is seen on biopsy for HSP?

Answer 24

a leukocytoclastic vasculitis is seen on biopsy, but IgA immune complexes are a more specific finding when direct immunoflueorescence is performed