[Atypical Sézary syndrome in a young subject].

Sézary syndrome accounts for 5% of cutaneous T-cell lymphomas, with mean age of onset of 60 years. Erythroderma associated with palmoplantar keratoderma and lymphadenopathy is the usual clinical presentation, but the disease has potentially confusing polymorphic clinical features.We report the case of a 27-year-old patient with no notable disease history, presenting generalized non-pruritic dermatosis for 3 months, with erythema and papules, and follicular distribution, localized to the limbs, the trunk and the face. Palmoplantar keratoderma was associated with acral edema. The clinical presentation was initially evocative of pityriasis rubra pilaris. Laboratory tests showed hyperlymphocytosis with Sézary cells in the blood. A diagnosis of grade IVA Sézary syndrome was made based on the skin biopsy results and the PET scan. Screening for KIR3DL2 on T-cells in blood was positive. Extracorporeal photochemotherapy was initiated but cutaneous relapse occurred, leading to combined treatment with bexarotene, which proved ineffictive. Despite numerous chemotherapies (cyclophosphamide, doxorubicin, vincristine, etoposide and prednisone, then dexamethasone, oxaliplatin and cytarabine, associated with brentuximab, vedotin, and, ultimately, clofarabine and endoxan), the patient died after 9 months.Our case illustrates an atypical clinical presentation of cutaneous lymphoma in a young patient. With a fatal outcome in 9 months despite 5 different lines of treatment, our case highlights the aggressive nature of Sézary syndrome as well as the difficulties involved in treating this disease.A diagnosis of Sézary syndrome must be considered in the event of atypical dermatosis in patients of all ages. The presence of lymphomatous clonal cells and Sézary cells in the blood, immunophenotyping of lymphocytes in blood and marrow, and a second reading of the cutaneous biopsy results enabled us to make a diagnosis of Sezary syndrome.