Cutaneous drug reactions

Question 1

Most common types of cutaneous drug reactions

Answer 1

1. Maculopapular
2. Urticarial
3. and fixed drug eruptions

Question 2

Most common time frame for onset of drug eruption

Answer 2

Usually within 1-2 weeks of starting drug

Question 3

Maculopapular drug eruptions

Answer 3

Difficult to distinguish from viral exanthems, often pruritic, start on trunk and spread out symmetrically (hands and soles usually spared)

Question 4

Ampicillin drug rashes

Answer 4

Two types: 1) Urticarial and 2) Maculopapular. Okay to give ampicillin/other penicillins to patients with history of maculopapular rash but NOT urticarial

Question 5

MCC of urticarial drug eruptions

Answer 5

Aspirin, penicillin, and blood products

Question 6

MCC of morbilliform drug eruptions

Answer 6

Ampicillin, amoxicillin, Bactrim, and allopurinol

Question 7

Three mechanisms of drug-induced urticaria

Answer 7

1. Anaphylactic and accelerated reactions
2. Nonimmunologic histamine release
3. Serum sickness

Question 8

MCC of anaphylactic/accelerated reactions

Answer 8

Penicillins. Can investigate vis skin testing. Only 5% cross reactivity between patient allergic to penicillins and cephalosporins. Rxn within minutes to hours

Question 9

Serum sickness drug rxn timeline

Answer 9

Usually see urticaria 4-21 days after drug ingestion. Get systemic signs.

Question 10

NonIgE Induced urticaria

Answer 10

Common with aspirin and NSAIDs. Urticaria frequently appears on face first and spreads caudally. Antihistamines not as effective in treating

Question 11

Nonimmunologic histamine releasers

Answer 11

Things that make you itch via mast cells releasing histamine: opioids, lobster, polymyxin B, strawberries

Question 12

DRESS Syndrome Etiology

Answer 12

MCC of mortality is fulminant hepatitis
Onset 2-6 weeks after drug administration
MCC are anti-convulsants and sulfmonamides (Dapson, sulfasalazine)

Question 13

DRESS syndrome clinical presentation

Answer 13

Begins with pruritus and fever followed by morbilliform rash

Question 14

Erythema Multiforme and TEN

Answer 14

Reactions occur on skin and mucous membranes. EM usually presents with targetoid lesion with central duskiness (can also see it in association with mycoplasma or herpes infxn)
MCC death in TEN is fluid loss
MCC are sulfonamides, NSAIDs, and anticonvulsants

Question 15

Acute generalized exanthematous pustulosis (AGEP)

Answer 15

Occurs acutely after drug administration, multiple non-follicular sterile pustules
MCC are CCBs, NSAIDs, anti-convulsants, beta-lactam and macrolide antibiotics
Must rule out generalized pustular psoriasis

Question 16

Other patterns of drug eruptions

Answer 16

Acneiform (think oral steroids/abuse of anabolic steroids as possible causes)
Eczema (variant known as baboon syndrome)
Photosensitive (phototoxicity vs. photoallergy)
Small vessel necrotizing vasculitis
Lymphomatoid

Question 17

Fixed Drug eruption

Answer 17

Single/multiple Red plaques or blisters that recur at same site with each exposure (~ around 2 hrs with refractory period)

Question 18

Specific common fixed drug eruptions

Answer 18

Tetracyclines and co-trimazole (lesions on glans penis)

Pseudoephedrine (non-pigmented lesion)

Question 19

Tx of fixed drug eruption

Answer 19

Topical steroids

Question 20

Blistering drug reactions

Answer 20

MCC are NSAIDs

Can look like linear IgA dermatosis, pemphigus/BP, or pseudoporphyria

Question 21

Exfoliative erythroderma

Answer 21

Can be seen not only with drug rxns but also CTCL, PRP, and psoriasis

Question 22

Lichenoid drug reaction

Answer 22

Look like generalized lichen planus and latent period between drug administration and reaction is between 3 weeks and 3 years
MCC are gold and antimalarials

Question 23

Lupus like Drug eruption MCC

Answer 23

Hydralazine, procainamide, isoniazid, methyldopa, quinidine, minocycline, and chlorpromazine.
Association with anti-TNF drug also reported

Question 24

Clinical presentation of drug induced lupus

Answer 24

Milder sx but still see arthralgias, fever, malaise, etc
Cutaneous signs much less common than in SLE although there is an SCLE variant
Rxn is dose related

Question 25

Lab w/u in drug induced lupus

Answer 25

Classically ANA and anti-histone positive

Typically negative for dsDNA

Question 26

Management of drug induced lupus

Answer 26

D/C medication and should resolve within weeks to months

Question 27

Chemotherapy induced acral erythema

Answer 27

MCC methotrexate, cytarabine, doxorubicin, 5-FU, and bleomycin
Dose dependent reaction

Question 28

Cutaneous complications of chemo

Answer 28

Stomatitis, alopecia, onychodystrophy, chemical cellulitis, phlebitis, palmoplantar erythema, and hyperpigmentation

Question 29

Interstitial granulomatous drug rxn

Answer 29

Tender, erythematous to violaceous plaque with predilction for skin folds