Dupilumab therapy in Sézary syndrome misdiagnosed as atopic dermatitis: A case report

Dear Editor, A 48-year-old Japanese woman with generalized erythroderma and intense pruritus was referred to our clinic. She had suffered from severe atopic dermatitis (AD) since infancy, which had developed into erythroderma within the last 2 years. She had no medical history of cyclosporin therapy but had received three injections of dupilumab following the diagnosis of AD, 2 months before her first visit. However, the therapy was not effective for the skin symptoms at all. Physical examination showed severe exfoliative erythroderma with superficial lymph node swelling (Fig. 1a–c). Laboratory studies revealed a white blood cell count of 13 880/lL with 11% S ezary cells (Fig. 1d); results for the human T-cell leukemia virus type 1 antibody were negative. Flow cytometric analysis revealed that her blood CD4/8 ratio was 3.6, whereas Southern blot analysis from peripheral blood showed clonal rearrangement of T-cell receptor genes. Histological examination revealed marked acanthosis with exocytosis of atypical lymphoid cells forming Pautrier’s microabscess (Fig. 1e). Most atypical cells in the skin were immunohistochemically CD4-positive T cells (Fig. 1f). Biopsy specimens from the inguinal lymph node showed large, atypical lymphoid cells with preserved lymph node