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.