Author: Dr Ian Coulson, Dermatologist, United Kingdom (2023)
Edited by the DermNet content department
This 25-year-old man has got round, brown, scaly patches over his chest. It has been diagnosed as a fungal infection but has not responded to oral terbinafine for two weeks.
The superficial brown scaly patches are highly suggestive of a yeast infection called pityriasis versicolor — it is due to a yeast called Malassezia and not a dermatophyte fungus.
The best way to confirm the diagnosis is by taking skin scrapings. The yeast pseudohyphae and spores are said to resemble spaghetti and meatballs when looked at using a potassium hydroxide wet preparation on microscopy.
Unfortunately it does not respond to oral terbinafine, which is highly active against dermatophyte fungi but not the causative yeast.
It can be treated by using topical azole shampoos or creams, or a short course of oral itraconazole.
See: Pityriasis versicolor.
