Erythema multiforme

Erythema multiforme (EM) is an acute and self-limited type IV hypersensitivity reaction. A large number of triggers have been identified including infections and drugs. The strongest association is seen with herpes infections. The localized version of EM is called EM minor. EM major and Stevens-Johnson syndrome (SJS) are considered severe forms of the same illness. It can affect almost any age group but the incidence is highest in young adults and children.

Clinical features:
About half of all patients have some prodrome symptoms like fever, cough, vomiting, bowel disturbance. EM minor does not involve mucosa which may be involved in EM major and SJS. Some of the lesions are characteristically target shaped. Lesions starts as small erythematous macules that grow to a size of about 2 cm over 1-2 days. Another lesions (a papule or a vesicle) develops in the center giving the target like appearance. The periphery may change color to become purple or violet colored.

Other than HSV the following infections have been associated with EM: Adenovirus, Coxsackievirus, Borreliosis, Bartonella, Coccidioidomycosis, Diphtheria, CMV, Echoviruses, Enterovirus, Epstein-Barr virus, Hepatitis viruses, Influenza virus, Measles, Mumps, Parvovirus B19, Legionella, Neisseria, Mycobacteria, Pneumococci, Proteus, Pseudomonas, Salmonella, Staphylococcus, Treponema, Francisella, Vibrio, Yersinia, Mycoplasma, Trichomonas and Toxoplasma.

Drugs associated with EM include: Penicillins, vancomycin, tetracyclines, cephalosporins, ciprofloxacin, erythromycin, sulfonamides, trimethoprim-sulfamethoxazole, anticonvulsants, aspirin, NSAIDS, anti-tuberculosis drugs, albendazole, allopurinol, corticosteroids, fluconazole, griseofulvin, hydralazine, indinavir, nevirapine, methotrexate, nifedipine and nystatin.

Tattoos, collagen vascular diseases and cancers can also trigger EM.

Treatment:
-Removal/treatment of the trigger if it can be identified.
-Local skin and mucosal care.
-Topical steroids are not helpful in most but can be tried.