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Pathology - Erythema multiforme
Definition: An inflammatory dermatosis characterized by unique targetoid lesions clinically and an interface reaction pattern histologically.
Epidemiology: • Fairly prevalent. • Primarily impacts the youth, encompassing youngsters.
Etiology • The majority of cases are associated with current or prior infections of the herpes simplex virus (HSV), which may not always be clinically evident. • Additional infectious organisms, such as Mycoplasma, have been implicated. • Pharmaceuticals are also acknowledged as a causative factor. Pathogenesis • Believed to signify a delayed-type hypersensitivity response to HSV antigens conveyed to the skin via circulating lymphocytes.
Presentation: Discrete circular erythematous patches, measuring 1–2 cm, with central darkening that may form blisters, referred to as 'target' lesions. • The majority of instances pertain to the extremities. • Mild oral involvement is prevalent.
Histopathology • Biopsies reveal interface dermatitis typified by a superficial lymphohistiocytic inflammatory infiltrate, substantial basal cell vacuolar degeneration, and keratinocyte death. • Instances of significant basal cell destruction may lead to subepidermal clefting and blister formation.
Prognosis: Most instances are self-limiting; however, recurring episodes are prevalent.
Definition: An inflammatory dermatosis characterized by unique targetoid lesions clinically and an interface reaction pattern histologically.
Epidemiology: • Fairly prevalent. • Primarily impacts the youth, encompassing youngsters.
Etiology • The majority of cases are associated with current or prior infections of the herpes simplex virus (HSV), which may not always be clinically evident. • Additional infectious organisms, such as Mycoplasma, have been implicated. • Pharmaceuticals are also acknowledged as a causative factor. Pathogenesis • Believed to signify a delayed-type hypersensitivity response to HSV antigens conveyed to the skin via circulating lymphocytes.
Presentation: Discrete circular erythematous patches, measuring 1–2 cm, with central darkening that may form blisters, referred to as 'target' lesions. • The majority of instances pertain to the extremities. • Mild oral involvement is prevalent.
Histopathology • Biopsies reveal interface dermatitis typified by a superficial lymphohistiocytic inflammatory infiltrate, substantial basal cell vacuolar degeneration, and keratinocyte death. • Instances of significant basal cell destruction may lead to subepidermal clefting and blister formation.
Prognosis: Most instances are self-limiting; however, recurring episodes are prevalent.
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