Nonpigmenting fixed drug eruption: a new case due to betahistine.

We describe a new case of a seldom reported subset of fixed drug eruption, the nonpigmenting type. Aside from their fixed nature and their well-demarcated margins, pigmenting and non-pigmenting subsets of fixed drug eruption exhibit well-separated clinical and histological features allowing easy recognition. The precise physiopathology is currently unknown in both conditions, but a delayed hypersensitivity mechanism is likely. The nature of the inducing drugs of the nonpigmenting eruption is discussed.