Rapid reversal of hyperpigmentation in pityriasis versicolor upon short-term topical cycloserine application.

The clinical phenomena of pityriasis versicolor (PV), a common Malassezia-associated skin disease, such as hyperpigmentation, depigmentation and fluorescence of the lesions may at least partly be explained by the generation of Trp-derived indole pigments through the action of transaminase 1 (TAM 1). Cycloserine, a TAM inhibitor, was able to completely inhibit pigment production in M. furfur in vitro in a dose-dependent manner. Application of a 0.2-mol l(-1) aqueous cycloserine solution b.i.d. for 5 days in three patients with hyperpigmented PV resulted in complete healing within 3-5 days without side-effects. Topically applied TAM inhibitors may therefore represent a new therapeutic principle for prophylaxis and therapy of PV, thus underlining the importance of the TAM pathway for the pathogenesis of the disease.