In the current work we demonstrate that CD22, a sialic acid-binding lectin previously exclusively described in B cells, is expressed in malignant T cell lines derived from skin lesions of MF patients (MAC-1, MAC-2A, MyLa2059 and PB2B) and in situ in lesional skin from CTCL patients. The gene discussed is CD22; the disease is primary cutaneous T-cell non-Hodgkin lymphoma.