Cutaneous drug reactions imitating dermatoses]

Cutaneous adverse drug reactions are frequent and present with heterogenous clinical manifestations. Increasingly, case reports describe drug reactions which mimic dermatoses, although exact data on prevalence are missing. Psoriasiform, lichenoid and pityriasiform exanthems are most frequent. The differentiation of these variants from the respective authentic dermatoses is difficult and only a few clinical and histological criteria are helpful. Other dermatoses like lupus erythematosus or bullous autoimmune dermatoses (pemphigus vulgaris, bullous pemphigoid) can be induced by drugs as well. These drug-triggered variations are classified as distinct subclasses of the respective dermatosis. Exact history and evaluation of the clinical course are essential for the diagnosis of drug reactions mimicking dermatoses and present an important challenge for the clinician. A clear-cut differentiation between the genuine dermatosis and its drug-driven simulator is not always possible.