ABSTRACT
Dupilumab, a human monoclonal antibody targeting the interleukin-4 receptor α, has exhibited rapid and remarkable therapeutic efficacy in numerous clinical trials focusing on moderate-to-severe atopic dermatitis and prurigo nodularis. Nonetheless, instances of mycosis fungoides have been reported in patients undergoing dupilumab treatment for atopic dermatitis. We present two cases: a 36-year-old woman and a 64-year-old man who presented to our dermatology clinic with erythematous papules and plaques. Following skin biopsy, both patients were diagnosed with chronic eczematous dermatitis with prurigo. Erythematous plaques notably increased after 9 months and 1 month of dupilumab treatment, respectively. Subsequent biopsies confirmed histopathological markers consistent with mycosis fungoides. The first patient underwent chemotherapy for lymph node metastasis, while the second received oral acitretin, narrow-band ultraviolet B, and topical corticosteroids.