Mogamulizumab‐associated rash (MAR) is one of the most common adverse events (AE) of the anti‐C‐C chemokine receptor type 4 (CCR4) antibody mogamulizumab, which is approved as a second‐line therapy for the treatment of mycosis fungoides (MF) and Sézary syndrome (SS).1 Here, CCR4 is linked to mycosis fungoides.