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Drug Eruptions

»	A patient presents to your office with a 10-page typed out medical history. She states that she is “allergic” to twenty different medicines. Is she likely to have drug allergies or drug intolerances to most of these drugs?
»	Name some nonimmunologic drug reactions.
»	What is the most common manifestation of an adverse drug reaction?
»	How does a cutaneous drug eruption typically present?
»	How should a suspected drug reaction be evaluated?
»	Which commonly used drugs are most likely to produce a cutaneous reaction?
»	Can preexisting diseases enhance the chance of getting a maculopapular skin eruption when using amoxicillin or ampicillin?
»	What infectious disease increases the chance of a cutaneous adverse reaction to trimethoprim-sulfamethoxazole?
»	Which feared drug eruption results in sloughing of the entire skin surface and mucous membranes?
»	Why do some patients get toxic epidermal necrolysis?
»	What is the difference between erythema multiforme major, Stevens-Johnson syndrome, and toxic epidermal necrolysis?
»	What drugs are typically associated with Stevens-Johnson syndrome?
»	Which type of drug reaction can result in a quick death?
»	What class of drugs is the most common cause of anaphylaxis?
»	Name the drugs most likely to induce urticaria.
»	How is drug-induced urticaria mediated?
»	A 45-year-old white man comes to the emergency room with large areas of nonpitting edema over the face, eyelids, neck, tongue, and mucous membranes, which developed 6 hours ago. Ten days earlier, he started a new drug for hypertension. What is the most likely cause of his reaction?
»	A patient is evaluated for a several-day history of fever, malaise, urticaria, arthralgias, lymphadenopathy, and a peculiar erythema along the sides of his palms and soles. He has been started on several new medications in the last few weeks. What is the most likely diagnosis?
»	A man complains of a recurrent burning eruption on his penis. He develops a single blister over the glans penis that heals over 1 to 2 weeks with hyperpigmentation. This same pattern has happened on three occasions in the last 2 years. What does he have?
»	How does drug-induced lupus erythematosus (LE) differ from idiopathic systemic lupus erythematosus (SLE)?
»	What drugs are usually associated with drug-induced LE?
»	Which drug is usually associated with erythema nodosum?
»	What drugs are associated with lichenoid drug eruptions?
»	Name the drugs most likely to produce cutaneous hyperpigmentation and discoloration.
»	What drugs can produce subepidermal bullae and erosions on the dorsum of the hands?
»	Name two drugs that commonly exacerbate porphyria cutanea tarda.
»	A 30-year-old white woman is evaluated with a new case of “acne.” Over the last few days, she has suddenly developed erythematous follicular papules and pustules over her upper trunk. She was admitted 3 weeks earlier with an acute exacerbation of SLE that is now improving. What is the most likely diagnosis?
»	A middle-aged man who is a dialysis patient presents to your clinic with a “woody” appearance to his legs. He had an MRI with gadolinum-containing contrast a few months prior. What might he be suffering from?
»	Describe a typical presentation of warfarin necrosis.
»	Name and describe the two types of photoinduced drug eruptions.
»	What drugs commonly cause phototoxic drug reactions?
»	What drugs commonly cause photoallergic drug reactions?
»	What is AGEP? How does it present?
»	You have been treating a patient for severe, scarring acne with an oral medication for the last three months. Her acne looks great but now she is starting to lose hair. What drug are you most likely using?

What is the difference between erythema multiforme major, Stevens-Johnson syndrome, and toxic epidermal necrolysis?

This is a critical and important question that is difficult to answer because this nosological nightmare continues to be controversial. The short version of these distinctions is as follows:

Erythema multiforme major is best defined as presentation with targetoid skin lesions that are typical of erythema multiforme, with a more severe variant that is more likely to demonstrate oral lesions, fever, and systemic symptoms. While this variant can be drug-induced, it is more commonly induced by infections such as herpes simplex and Mycoplasma. Some dermatologists consider this to be in the spectrum of Stevens-Johnson syndrome. Microscopically, the keratinocytes are being damaged by lymphocytes (satellite cell necrosis).
Stevens-Johnson syndrome is most commonly defined as presentation with widespread targetoid lesions that are a flat and atypical when compared to the more defined lesions of erythema multiforme. Lesions are also more frequently purpuric. As in the case of erythema multiforme major, the patients may have fever and systemic symptoms. In contrast to erythema multiforme major, the lesions are more likely to become confluent and develop large areas of blisters and detachment of the epidermis. While some cases are idiopathic or induced by infections, the majority are drug induced. Histologically, the findings are identical to erythema multiforme in that the keratinocytes demonstrates satellite cell necrosis. Some dermatologists arbitrarily define this condition as affecting less than 30% of the body surface, and some authorities even recognize a Stevens-Johnson syndrome/toxic epidermal necrosis overlap syndrome.
Toxic epidermal necrosis is best defined as a blistering disorder with extensive detachment of the skin that is almost always drug induced, although there are exceptions. Many of the drugs that produce classic Stevens-Johnson syndrome also produced toxic epidermal necrolysis. Targetoid lesions are not usually present but if present are atypical. Microscopically, biopsies are cell poor and cells usually appear to become necrotic without evidence of satellite cell necrosis, suggesting a soluble factor. Some dermatologists arbitrarily differentiate this from Stevens-Johnson syndrome if more than 30% of the cutaneous surface is involved, although many dermatologists feel that toxic epidermal necrolysis and Stevens-Johnson syndrome represent a spectrum of disease.