Case Report: Severe mixed autoimmune hemolytic anemia associated with acute cytomegalovirus infection in an immunocompetent adult.

Background: Cytomegalovirus (CMV)-associated hemolytic anemia (HA) is rare in immunocompetent hosts and may present with heterogeneous serologic phenotypes, including direct antiglobulin test (DAT)-negative hemolysis, warm autoimmune hemolytic anemia (AIHA), cold antibody-mediated AIHA, and rarely mixed AIHA. Because mixed AIHA requires evidence of both warm autoantibodies and clinically significant cold autoantibody activity, this phenotype may be underrecognized without comprehensive immunohematologic testing. Case presentation: We report a case of CMV-associated HA that was diagnosed as mixed AIHA by comprehensive immunohematologic assessment and successfully managed with combination therapy. A 59-year-old immunocompetent man presented with a 7-day history of fever, sore throat, and fatigue. Initial evaluation revealed marked hepatocellular and cholestatic liver injury, positive CMV IgM with negative CMV IgG, and serum CMV DNA of 2.28 × 10 Conclusions: CMV-associated HA may rarely present as severe mixed AIHA in immunocompetent adults. In severe or atypical cases, comprehensive immunohematologic evaluation beyond routine DAT, including extended DAT, cold agglutinin titration, and thermal amplitude testing, is essential for accurate subtyping. In severe cases, early integrated therapy targeting both CMV replication and immune-mediated hemolysis may be required.