Mixed diagnoses – 10 cases (4 of 11)

The patient presents with numerous, slightly scaly hypopigmented patches on her trunk and proximal upper limbs, characteristic of pityriasis versicolor (sometimes incorrectly called tinea versicolor), a yeast infection. Previously classified as M. furfur, there are seven lipophilic species of Malassezia, which are normal human saprophytic yeasts but may become pathogenic in their mycelial form. Pityriasis versicolor is most often due to M. globosa. It results in mild inflammation (pink) and hyper- (brown) or hypo- (white) pigmentation with a bran-like scale.

Mild or localised pityriasis versicolor may clear with repeated applications of a topical imidazole cream, lotion or spray (especially ketoconazole cream/shampoo). However, it is more effective to use an oral imidazole (ketoconazole, fluconazole or itraconazole) for extensive infections. There are various regimes of intermittent or continuous therapy; it may be helpful to 'sweat' the medication through the skin by exercising an hour after ingestion. Relapses are common, so once monthly single-day prophylaxis is helpful. Oral imidazoles should not be used in pregnancy. Pityriasis versicolor does not respond to oral griseofulvin or terbinafine.