CD200 Breaks the Diagnostic Dilemma between Atypical CLL and Other CLPNS

Chronic lymphocytic leukemia (CLL) is characterized by a monoclonal lymphocytosis of small mature-appearing CD5+, CD23+ B lymphocytes. CLL cells arise from the bone marrow. Two subtypes of CLL are morphologically described in the FAB classification including typical and atypical forms, however, no strict morphologic or immunophenotypic criterion is mentioned in the WHO classification. It is further difficult to differentiate atypical CLL from other chronic lympho-proliferative neoplasms (CLPN). Hereby we present a case of a 51 year old male of atypical CLL and the utility of the marker CD200 in the differentiation of aCLL from other CLPNs.