Human Papilloma Virus Type 94–Associated Flat Warts Developing Repeatedly During Tofacitinib Treatment: A Case Report and Review

Flat warts are typically caused by human papillomavirus (HPV) type 3 or 10, while HPV 94 is rarely detected. The warts on a 76-year-old Japanese male with rheumatoid arthritis (RA) appeared after 8 months of tofacitinib treatment but disappeared upon switching to filgotinib. However, the warts reappeared when tofacitinib was resumed. Histopathological and DNA sequencing confirmed HPV 94. While Janus kinase (JAK) inhibitors are known to increase viral reactivation risks, including herpes zoster, this case highlights a possible link between tofacitinib and HPV 94-related flat warts. Tofacitinib may suppress IL-15 signaling, weakening antiviral immunity and promoting HPV reactivation. Although HPV-specific immunity in RA- and tofacitinib-treated patients remains unclear, this case provides new insights into JAK inhibitor-related viral reactivation, particularly for HPV 94-associated flat warts.