A rare case of white piedra caused by Candida orthopsilosis

White piedra (WP) is a fungal infection that affects hair shafts, resulting in the formation of soft nodules that can be white, gray, or brown. While it was initially believed to be caused by Trichosporon beigelii, genetic analysis has reclassified Trichosporon inkin, T. ovoides, and T. cutaneum, as the primary causative agents of WP. In this report, we present a rare documented case of WP caused by Candida orthopsilosis, as a member of Candida parapsilosis complex, occurring without presence of Trichosporon in a temperate region in northern Iran.

A 3-year-old girl visited a dermatology clinic with complaints of hair knots in the occipital area, particularly around the ears, that were difficult to remove. These symptoms have persisted for two months. The patient has no history of gym classes or kindergarten attendance and was not taking any specific medications. No other areas of her body were affected, and none of her family members reported experiencing any symptoms. Fungal isolates were identified using PCR-RFLP and confirmed by sequencing. Antifungal susceptibility testing of the isolates was conducted based on CLSI M27-S3 guidelines.

We suggest that C. orthopsilosis can cause WP independently of Trichosporon species, particularly in temperate regions. Future studies should establish a clear relationship between the yeast responsible for WP and its geographic location. This case could increase awareness among dermatologists and laboratory physicians, emphasizing that the growth of Candida species should not be dismissed as contaminant.