Cold agglutinin disease.

Development of the Coombs test has led to rapid progress in the recognition of various autoimmune hemolytic anemias. Cold agglutinin disease, a relatively rare disorder, occurs in idiopathic and secondary forms, the latter often in association with diseases that alter the immune status. The higher the titer of cold agglutinin, the greater is the thermal range of its activity. One of the characteristic clinical manifestations of the disease is striking cyanosis in acral areas on exposure to cold, which abates quickly on warming. This parallels the accelerated hemolysis at cold temperatures, which is reversible as heat is applied. In some patients, however, the disease is covert and is discovered only incidentally. The report of such a case is included.