A Case of Oral Candidiasis Caused by Candida dubliniensis During Treatment of Humanized Monoclonal Antibody to Interleukin-17A.

We report the case of a 77-year-old woman who had been diagnosed with psoriasis vulgaris at another hospital at age 33 and treated with various therapies since then. At 61 years old, she was diagnosed with psoriatic arthritis with phalangitis, swelling of both hands, and sacroiliac arthritis, and was treated with oral immunotherapy. At age 76, treatment with a humanized monoclonal antibody to interleukin-17A (ixekizumab) was started due to increased pain associated with her hand inflammation. After ten months of this treatment, she visited our hospital with the complaint of tongue pain and white fungi on the tongue surface. Direct KOH examination of the fungi showed pseudomycelia and spores, and fungal culture (CHROMagar®Candida) showed green and dark green wet colonies. Sequencing of the D1D2 region of ribosomal RNA gene of the nuclear DNA of fungi from the colony identified Candida dubliniensis. She was treated with amphotericin B gargle (Fungizone®syrup) for two weeks, and the lesion improved. Since then, the patient has been treated with ixekizumab with no recurrence of oral candidiasis.