Histopathological study in some drug eruptions

Drug eruptions are cutaneous adverse reactions due to drug administration. One drug can cause numerous patterns of drug eruptions. The same pattern of drug eruption can be caused by drugs with different chemical structures. Only fixed drug eruption is characteristic while the other manifestations can mimic various kinds of skin diseases. The pathogenesis of drug eruption may be an immunological and non immunological process or both. The diagnosis of drug eruption requires much effort in taking a complete history, dechalleng and rechallenge tests. Skin tests are useful in only some types of drug eruption. Laboratory tests for the diagnosis of drug eruption are available only for research purposes. In some cases, the histologic findings may be diagnostic. Avoidance of a suspected drug and substitution of non-cross reacting medication is a standard approach to the management of drug reaction.