"Morbilliform" (Maculopapular)

Most common drug eruption

Exanthem-like : pink/red papules and macules start on face or upper chest, can extend to limbs, variable pruritus

Onset in 7-14 days on first exposure, 1-3 on second exposure

Generally not life-threatening - does not proceed to anaphylaxis, so can be treated symptomatically

Urticaria

Wheal, hive, welt : pink, elevated severly pruitic plaque anywhere on body, often annular, caused by local edema, by definition, lasts <24 hours

If present >6 weeks, considered chronic, more in depth work up for trigger is performed

Pathophysiology : many causes - drugs, foods, infection, parasites, systemic diseases, stress

Antibody mediated hypersensitivity with antigen-IgE complex stimulating mast cells, leading to degranulation, release of proinflammatory mediators (histamine)

Dermographism

Writing on the skin produces an exaggerated wheal/flare in 2-5% of the population, sometimes associated with urticaria or systemic itching.

Fixed Drug Eruption

One or more annular or oval bruise-like patches often on the lips or genitalia, can be anywhere, resolves with hyperpigmentation, recurs at the same site with re-exposure to the drug

Pathophysiology - results from systemic drug exposure, thought to be cell mediated propagated by CD8+ T cells, meidcations taken episodically, such as pain relievers, antibiotics, laxatives are often to blame - pseudophedrine, ibuprofen, TCNs, sufas, metronidazole, barbituates, OCPs, Big Red soda

Fixed Drug Eruption

One or more annular or oval bruise-like patches often on the lips or genitalia, can be anywhere, resolves with hyperpigmentation, recurs at the same site with re-exposure to the drug

Pathophysiology - results from systemic drug exposure, thought to be cell mediated propagated by CD8+ T cells, meidcations taken episodically, such as pain relievers, antibiotics, laxatives are often to blame - pseudophedrine, ibuprofen, TCNs, sufas, metronidazole, barbituates, OCPs, Big Red soda

Erythema Multiforme

Characterized by target lesion - central dusky papule/patch with 2 or more concentric erythematous rings, usually symmetric with predilection for palms, soles, dorsal surfaces of hands, extensor surfaces of forearms and legs

EM is acute self-limited inflammatory, mild prodrome of fever, pharyngitis, cutaneous lesions that are usually asymptomatic

Etiology - Secondary to a variety of agents, most common is herpes simplex (50%); other infections - mycoplasma (most common bacteria), histoplasmosis, coccidiodes, psittacosis, influenza A; drugs - sulfonamides, NSAIDs, PCN, hydratoin derivatives, barbituates, phenolphthalein; less commonly associated with malignancy or autoimmune disorders

Diagnosis-skin biopsy to find epidermal blister, immunofluorescence helpful to distinguish from other subepidermal blisters

Cultures of skin, nose, throat, conjunctiva indicated

Erythema Multiforme

Characterized by target lesion - central dusky papule/patch with 2 or more concentric erythematous rings, usually symmetric with predilection for palms, soles, dorsal surfaces of hands, extensor surfaces of forearms and legs

EM is acute self-limited inflammatory, mild prodrome of fever, pharyngitis, cutaneous lesions that are usually asymptomatic

Etiology - Secondary to a variety of agents, most common is herpes simplex (50%); other infections - mycoplasma (most common bacteria), histoplasmosis, coccidiodes, psittacosis, influenza A; drugs - sulfonamides, NSAIDs, PCN, hydratoin derivatives, barbituates, phenolphthalein; less commonly associated with malignancy or autoimmune disorders

Diagnosis-skin biopsy to find epidermal blister, immunofluorescence helpful to distinguish from other subepidermal blisters

Cultures of skin, nose, throat, conjunctiva indicated

Stevens Johnson Syndrome (formerly Erythema Multiforme Major)

Prodrome of upper respiratory infection, fever, and painful skin

Two or more mucosal surfaces involved with vesicles, bullae, erosion and hemmorhagic crests of the conjunctiva, oral mucosa, genitalia

Severe bullous lesions are also found on the extremities and trunk but <10% of body surface area

Pathophysiology : Medications - NSAIDs, Antibiotics, anti-epileptics, occurs 7-21 days after the start of the medication

Prognosis - can be fatal, mortality rate is 1-5% for SJS, patients are usually treated in a burn unit

Stevens Johnson Syndrome (formerly Erythema Multiforme Major)

Prodrome of upper respiratory infection, fever, and painful skin

Two or more mucosal surfaces involved with vesicles, bullae, erosion and hemmorhagic crests of the conjunctiva, oral mucosa, genitalia

Severe bullous lesions are also found on the extremities and trunk but <10% of body surface area

Pathophysiology : Medications - NSAIDs, Antibiotics, anti-epileptics, occurs 7-21 days after the start of the medication

Prognosis - can be fatal, mortality rate is 1-5% for SJS, patients are usually treated in a burn unit

Toxic Epidermal Necrolysis

Prodrome of upper respiratory infection, fever, and painful skin

Two or more mucosal surfaces involved with vesicles, bullae, erosion and hemmorhagic crests of the conjunctiva, oral mucosa, genitalia

Severe bullous lesions are also found on the extremities and trunk with >30% of body surface area affected

Pathophysiology : Medications - NSAIDs, Antibiotics, anti-epileptics, occurs 7-21 days after the start of the medication

Prognosis - can be fatal, mortality rate is 25-35% for TEN, patients are usually treated in a burn unit

Toxic Epidermal Necrolysis

Prodrome of upper respiratory infection, fever, and painful skin

Two or more mucosal surfaces involved with vesicles, bullae, erosion and hemmorhagic crests of the conjunctiva, oral mucosa, genitalia

Severe bullous lesions are also found on the extremities and trunk with >30% of body surface area affected

Pathophysiology : Medications - NSAIDs, Antibiotics, anti-epileptics, occurs 7-21 days after the start of the medication

Prognosis - can be fatal, mortality rate is 25-35% for TEN, patients are usually treated in a burn unit