Case Report: Cutaneous T-cell lymphoma associated with biologic therapy: three cases and a literature review.

Cutaneous T-cell lymphoma (CTCL) often presents with early-stage clinical features indistinguishable from atopic dermatitis (AD), posing significant diagnostic challenges. Recent studies have highlighted cases where patients initially diagnosed with AD and treated with biologic agents were subsequently reclassified as having CTCL, though the nature of this relationship remains poorly understood. In this report, we present two cases of mycosis fungoides and one case of Sézary syndrome (SS), all initially diagnosed as AD and treated with biologic agents, including dupilumab. Furthermore, we conducted a literature review exploring potential associations between AD, biologic agents, and CTCL. Our objective is to improve clinicians' ability to differentiate between AD and CTCL and to provide evidence supporting a possible association between biologic treatments and CTCL. Our findings highlight the need for heightened clinical vigilance and the routine use of skin biopsy in refractory eczematous presentations.