Cold agglutinin disease after chicken pox. An uncommon complication of a common disease.

Chicken pox, although common, is rarely associated with autoimmune hemolytic anemia. Reported here is the case of an 8-year-old boy who was found to have cold agglutinin disease and severe anemia several days after he contracted chicken pox. The cold agglutinin appeared to be a polyclonal immunoglobulin M antibody with anti-Pr specificity. To our knowledge, this is the fifth reported case of autoimmune hemolytic anemia and the second reported case of cold agglutinin disease with anti-Pr specificity to be associated with chicken pox.