Cycloserine-induced lichenoid drug eruption.

A 65-year-old male patient who has taken antituberculous drugs including cycloserine for 8 months showed multiple pruritic, violaceous, flat-topped papules and plaques on his back which had developed 5 months into therapy. Histopathologic findings were consistent with lichenoid drug eruption. Patch test with the drugs revealed a strongly positive reaction to cycloserine only. Four months after discontinuation of oral cycloserine, pruritus resolved and the lesions subsided without any new lesions. Cycloserine is one of the antituberculous drugs. Skin manifestations resulting from its administration are reported to be rare, but to our knowledge, this is the first case report of lichenoid drug eruption from its use.