Cutaneous reaction patterns

Question 1

Erythema multiforme

Answer 1

Cuteneous hypersensitivity reaction

Causes: viral infections most common (HSV in 50%, mycoplasma, others). Drugs (NSAIDS, Sulfa drugs, Antiepileptics, Antibiotics)

Question 2

Clinical features of erythema multiforme

Answer 2

Arises after HSV lesions have crusted or resolved

Abrupt onset of target lesions

Hands, feet and other acral sites

Prodrome rare

Non- toxic

Question 3

Erythema multiforme management

Answer 3

Supportive care for mild disease : topical corticosteroids, pain management

Sever mucosal disease: prednisone can be used , ophthalmology consult for ocular involvement

Question 4

Exanthematous Drug Eruption

Answer 4

AKA morbilliform drug rash
Most common drug reaction (can occur with any drug, most common antibiotics, anticonvulsants)
Idiosyncratic delayed (type 4) immune reaction

Clinical features: multi pink macules and barely palpable papules

Starts on face and trunk then spreads to extremities
Pruritic

Fever and mucosal involvement are typically absent

Course: onset 2-14 days after starting medication, subsequent occurences have faster onset, can start even after finishing treatment (AB)

Question 5

Exanthematous Drug Eruption Treatment

Answer 5

Discontinue culprit drug if possible

Supportive care for pruritus (oral antihistamines, topical corticosteroids)

REsolution: spontaneously resolves in 1-2 weeks, can resolve even with continuation of drug

Question 6

Lab results of Exanthematous Drug Eruption

Answer 6

Complete blood count

WBC normal (eosinophils are high)
H/H and platelts normals 

Liver panel AST and ALT are high, alk phos and bilirubin are normal

BUN and creatinine normal
DRESS:
Type 4 hypersensitivity, more common in adults, later onset 2-8 weeks after drug initiation

Causes: antiepileptics, sulfonamides, minocycline, allopurinol, antiretrovirals

Question 7

Exanthematous Drug Eruption Clinical features

Answer 7

Cutaneous involvement: most commonly morbilliform other cutaneous patterns sometimes seen

Facial edema , lymphadenopathy, fever

Question 8

Clinical features of DRESS

Answer 8

Most common organs involved
Liver: elevated transaminases
Hematologic: eosinophilia, atypical lymphocytes
Kidney: mild nephritis

Less commonly involved: heart, lungs, brain , GIT

Question 9

Treatment of DRESS

Answer 9

indentify and stop the culprit drug

Mild cases treated with supportive care (topical corticosteroids, oral antihistamines)

Severe cases (systemic corticosteroids, may require hospitilaztions)

Question 10

Prognosis and course of DRESS

Answer 10

10% mortalitly
slow resolution over weeks or months
Autoimmune disease may develop later (autoimmune thyroditis, diabetes mellitus, autoimmune hemolytic)

Question 11

Urticaria

Answer 11

20% of people will have urtcaria 
Patho physiology (release of histamine, bradykinin, LT C4, PG D2, other vasoactive)

Most commonly type 1 IgE- mediated

Question 12

Causes of urticaria

Answer 12

Idiopathic
Most commonly identified cause is URI

Other causes: other infections, drug allergies, food allergies

Question 13

Clinical features of urticaria

Answer 13

Classical lesion is wheal

individual lesion last under a day
Can last up to 6 weeks

Question 14

Angioedema

Answer 14

treatment H1 antihistamines (Loratidine,certizine, fexofenadine), Sedating H1 anti histamines (diphenhydramine)

Prednisone may help sever cases

Angioedema dn anaphylaxis require emergent care

Question 15

SJS/TEN

Answer 15

hypersensitivity reaction
Causes: infections more common in kids (viral and myco)
Meds: NSAIDs, sulfa drugs, alloprinol, antiepileptics, antibiotics, antiretrovirals

Malignancy and idiopathic

Risks: female, HIV, SLE, malignancy

Prodrome: occurs 1-14 days prior to cutaneous eruption, flulike illness (fever, malaise, pharyngitis, rhinitis, cough, headache, myalgias, arthralgias, anorexia, nausea, vomiting)

Starts as painful red macules and patches, rapidly evovles into blistering and necrosis

Affects skin and mucosa, Ocular nasal oral and or genital

Question 16

SJS/TEN systemic involvement and management

Answer 16

Acute: dehydration, malnutrition, pneumonitis, GI bleeding, sepsis
Mortality: SJS: 1-3%, TEN: 25-35%

Long term complications: mucocutaneous scarring, blinding, strictures, sicca syndrome

management: requires inpatient hospital care with multidisiplinary approach, maintain fluid and electorlyte balance, discontinue drug, pain management, meds: corticosteroids, IVIG

Question 17

vasculitis

Answer 17

inflammation and destruction of blood vessels, classified by size of vessel

leukocytoclastic vasculitis: AKA hypersensitivity vasculitis
Small messel vasculitis of skin with predominantly PMNs, affects children and adults

Approximately men=females
causes: 50% are idiopathic, Upper respiratory infection Group A strep infection, hep B and C HIV, drugs (Abs and NSAIDs), autoimmune disease (Rheumatoid arthritis,SLE, IBD), malignaancy

Clinical features: palpable purpura is characteristic, systemic involvement (fever, joint paain and swelling, GI bleed, renal involvement, cardiopulmonary involvement)

Prognosis: Good if skin limited, self resolves, chronic relapsing course in some, can be potentially fatal if systemic involvement

Treatment: supportice care (analgesics, rest and elevatin) treatment for more severe cases (corticosteroids, colchicine, dapsone, immunosuppressives )

Question 18

henoch schonlein purpura

Answer 18

subtype of leukocytoclastic vasculitis
Most common in children (peak 2-11 years old)
More common in males

Hallmark shin finding=palpable purpura on butt and legs,

Systemic involvement: arthritis, and arthralgias, GI (nausea vomit and pain, GI bleed, intussusception), nephritis, Rare-testes, lung and heart brain

Skin eruption resolves over 2-4 weeks, nephritis can develop up to 6 months later, even after skin eruption has resolved

Systemic involvemnet can cause longer lasting or permanent complications

Treatment and coarse: supportive care for pruritus (oral antihistamines, topicla corticosteroisds )
NSAIDS for pain, prednisone for sever cases