[Chronic cold agglutinin disease accompanied with an increase of CD20+/CD5+ cells; a case report].

A 61-year-old male complained of acrocyanosis and dark urine when exposing to cold temperatures. This had continued for several years. His physical examinations showed neither lymphadenopathy nor hepatosplenomegaly. Laboratory findings were as follows; RBC 305 x 10(4)/microliters, Hb 10.3 g/dl, reticulocytes 4.32%, platelets 27.3 x 10(4)/microliters, WBC 7,400/microliters with 50% lymphocytes, and a high cold agglutinin titer (2,048-fold) with anti-I specificity. Bone marrow smear preparations showed erythroid hyperplasia and increase of lymphocytes (52%). Immunophenotypic analysis showed an increase of CD20+/B-lymphocytes in peripheral blood (32.6%) and in bone marrow, and 94% of these cells co-expressed CD5. Most B-lymphocytes expressed surface IgM-lambda, suggesting a monoclonal proliferation of B-lymphocytes. At this point we diagnosed cold agglutinin disease (CAD) because there was no evidence of lymphoma, and the absolute number of peripheral blood lymphocytes was lower than the criteria of chronic lymphocytic leukemia (CLL) proposed by the International Workshop (1989). However, there still remains the possibility of the transitional form between "idiopathic" CAD and B-CLL or lymphoma.