A 71-year-old man presented with erythroderma and multiple nodular skin lesions over the face, scalp, upper limbs and trunk. The facial skin was thickened, producing the rare 'leonine facies' appearance. Investigations revealed the presence of atypical lymphoid cells in the peripheral blood, bone marrow and skin. The atypical lymphoid cells in the peripheral blood and bone marrow were positive for helper T-cell antigens (CD4, CD2, CD5 and CD7) on immunophenotyping by flow cytometry. The histopathology of skin showed dermal infiltration by atypical small lymphocytes with epidermotropism. These cells were positive for helper T-lymphocyte antigens on immunohistochemistry. A diagnosis of Sézary syndrome was made based on clinical, peripheral blood and immunophenotypical findings.