Abstract Cutaneous T-cell lymphomas (CTCL) comprise a group of diseases characterized by the accumulation of malignant T cells within the skin. Sezary syndrome represents an aggressive form of CTCL, in which the skin is diffusely affected and the peripheral blood is involved. It is characterized by the triad of generalized erythroderma, lymphadenopathy, and neoplastic T cells (Sezary cells) in the skin, lymph nodes, and peripheral blood. Leonine facies is rare and corresponds to the morphologic manifestation of diffuse dermal infiltration of the face. It can occur in cutaneous T-cell lymphomas that progress during years without therapy. We present the case of a 54-year-old man with Sezary syndrome presenting with leonine facies, unresponsive to conventional therapies; he exhibited a promising response to subcutaneous low-dose alemtuzumab. A 54-year-old male was observed in our department because of a four-year history of generalized pruritus and cutaneous lesions on the face. On physical examination he showed generalized erythroderma, lichenification, diffuse alopecia, madarosis, and diffuse infiltration of facial skin, particularly on the eyebrows and ears, giving the appearance of a leonine facies The full blood count revealed 18.59x10 9 /L leukocytes, 7.81 x10 9 /L neutrophils, 1.39 x10 9 /L lymphocytes, hemoglobin 15.2 g/dL, and platelets 395 x10 9 /L, with 45.5 percent of atypical lymphocytes. Biochemistry studies were relevant for high LDH (430 UI/L) and high β2-microglobulin (2341 ng/mL) levels. Thoracic, abdominal and pelvic CT scans were unremarkable and the bone marrow biopsy revealed invasion of atypical lymphocytic cells. Flow cytometry and molecular biology studies confirmed the presence of the phenotypically abnormal monoclonal CD4+ T cells in the peripheral blood and bone marrow. The diagnosis of Sezary syndrome (SS) (T4NxM0B2) was made. The patient started combined systemic chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) accomplishing four cycles with no response. A regimen of low dose subcutaneous (sc) alemtuzumab was then introduced, beginning with 3 mg in the first day, followed by 10 mg three times a week for twelve weeks. There was a transient interruption of the treatment at the fourth week, with a duration of six weeks, for asymptomatic reactivation of cytomegalovirus. We observed a marked reduction o
