Sean Klepper M.D.
Artur Zembowicz M.D....
- Most common in children and young adults, with a slight male predominance
- Seasonal variation, with a peak in the spring and summer
- Self-limiting, but commonly recurs
- Presents as multiple, symmetrically distributed maculopapules with a predilection for the extensor surfaces of the extremities
- As the lesions progress, their centers become ischemic and bluish, resulting in the classic target lesions, and blisters sometimes form.
- Oral lesions are also frequently present.
- The lesions often heal leaving postinflammatory hyperpigmentation.
- Frequent recurrent episodes of erythema multiforme are associated with herpes simplex infection, which is the most common etiologic agent of the disease.
- Many other infectious agents, especially Mycoplasma, drugs and malignancies have also been implicated.
- An additional association, known as Rowell syndrome, is with discoid or systemic lupus erythematosus.
- Basal cell hydropic degeneration, which may be severe enough to result in the formation of subepidermal clefts or vesicles
- Apoptosis of keratinocytes, ranging from focal to diffuse epidermal involvement
- Marked superficial dermal lymphohistiocytic inflammation with lymphocytic exocytosis and satellite cell necrosis
- Intra- and intercellular epidermal edema, sometimes resulting in spongiotic vesicles