-IBIS-1.5.0-
tx
cutaneous system
erythema multiforme
diagnoses

definition and etiology

definition: sudden inflammatory eruption of symmetrical, erythematous, edematous, bullous or other type of skin or mucous membrane lesions, usually from systemic causes

etiology: The most common cause is viral, but there is no identified cause in over 50% of cases. Known factors implicated include drugs (e.g. penicillin, barbiturates, antipyretics, sulfonamides, polio vaccines, although almost any drug can cause the reaction in a sensitive patient); infectious organisms (e.g. mycoplasma pneumonia, herpes simplex, coxsackie, histoplasmosis); and food allergies. It appears to be a hypersensitivity reaction, although the exact mechanism is unknown. Tissue damage at the site of the lesions is from release of highly reactive oxygen intermediates by polymorphonuclear leukocytes. The condition is seen most often in children and young adults. It is worse in the spring and fall, when it tends to occur spontaneously and last for 2-4 weeks.

signs and symptoms

signs and symptoms: onset is sudden; lesions are symmetrical
• areas most often involved include:
» extensor surface of extremities, dorsa of feet, face, lips, mouth, penis: 50% of lesions
» dorsum of the hand: usually the first area lesions appear
» lungs: 30%
» eyes: 91%
• lesions are edematous and reddened; target lesions (annular lesions of concentric circles with a central purpural area) are characteristic; may appear as bullae,
macules, papules, purpura, or urticaria
• systemic symptoms are often present: fever, arthralgia, malaise
• itching is variable among patients
• Stevens-Johnson Syndrome: severe form recognized by bullae on the oral mucosa, pharynx, conjunctiva and anogenital areas; skin ulcers may form and, if the eyes are involved, blindness may result after several days; condition can be fatal and is a medical emergency

lab findings:
• may see increased WBCs
• may see eosinophilia

course and prognosis

If the cause is found and removed, the prognosis is excellent. Minor cases often do not need medical care, but severe cases, especially with the presentation of bullae, may require hospital care. Corneal involvement requires intensive treatment under an ophthalmologist's supervision.

differential diagnosis

• other skin diseases


footnotes