CD25 expression is seen in Chronic lymphocytic leukemia (CLL), Hairy cell leukemia (HCL) & Hodgkin lymphoma. In cases of transformation of CLL/HCL into Diffuse large B-cell lymphoma (DLBCL) and gray zone lymphoma between DLBCL & Hodgkin lymphoma, CD25 expression can be used as a prognostic marker. CD25 positive DLBCL patients generally show a poor response to chemotherapy.