Oral manifestations of erythema multiforme.

Erythema multiforme is a reactive mucocutaneous disorder in a disease spectrum that comprises a self-limited, mild, exanthematic, cutaneous variant with minimal oral involvement (EM minor) to a progressive, fulminating, severe variant with extensive mucocutaneous epithelial necrosis (SJS and TEN). Significant differences exist among EM minor, EM major, SJS, and TEN with regards to severity and clinical expression; however, all variants share two common features: typical or less typical cutaneous target lesions and satellite-cell or more widespread necrosis of the epithelium. These features are considered to be sequelae of a cytotoxic immunologic attack on keratinocytes expressing non-self-antigens. These antigens are primarily microbial (viruses) or drugs and in rare instances histocompatibility antigens [5]. Although the precise pathogenesis is unknown, there is a tendency to consider EM both minor and major as part of one spectrum that is most often triggered by viral infections, and SJS and TEN as a separate one most often elicited by drugs with EM major and SJS representing a bridge in the continuum of EM. The oral manifestations of the spectrum of EM range from tender superficial erythematous and hyperkeratotic plaques to painful deep hemorrhagic bullae and erosions. Other mucosal surfaces including ocular, nasal, pharyngeal, laryngeal, upper respiratory, and anogenital may be involved. Scarring sequelae from ocular and pharyngeal involvement cause morbidity. The oral EM variant is an underrecognized form of EM. Most patients have chronic or recurrent oral lesions only, but one third have oral and lip lesions and one quarter have oral, lip, and skin lesions. This variant is a reaction pattern similar to EM minor, EM major, SJS, and TEN. The diagnosis of oral EM is one of exclusion. Careful clinical evaluation for other chronic mucocutaneous diseases, such as pemphigus, paraneoplastic pemphigus, mucous membrane pemphigoid, and lichen planus, is a necessary component of the diagnosis. The value of a biopsy specimen studied by both routine histopathologic and immunopathologic methods is fundamental to excluding the other causes for this variant of EM.