Can be caused by drugs (nonsteroidal
antiinflammatory drugs (e.g., ibuprofen, naproxen, valdecoxib, oxaprozin),
sulfonamides, penicillins, cephalosporins, erythromycin, tuberculostatics,
salicylates, pyrazolones, carbamazepine, phenobarbital, phenytoin), viral
(e.g., adenovirus, herpes simplex virus, Epstein-Barr virus,
cytomegalovirus, hepatitis A and B virus, measles virus, varicella virus,
mumps virus, influenza virus, coxsackie virus B5), bacterial (e.g., Proteus
species, Salmonella species, Mycobacterium species, Brucella species,
Corynebacterium diphtheriae), fungal (e.g., histoplasmosis), parasitic
(e.g., coccidiosis) or mycoplasma infections, endocrine factors, neoplasms,
collagen diseases, sarcoidosis, and physical factors. However, of all the
possible causative factors, only drugs, herpes simplex, and mycoplasma have
been implicated without doubt. The disease is speculated to be caused mainly
by a cell-mediated hypersensitivity reaction to a drug or another type of
antigen. Humoral involvement with the presence of IgM and C3 are part of the
immunologic reaction. These immune complexes are found in the vasculature
and at the dermal-epidermal junction and cause vasculitis and skin lesions.