Thanks to Dr. Hegarty for an excellent discussion on a case of a young woman presenting with subacute progressive B symptoms and acute jaundice found to have signs and symptoms of hemolytic anemia. Ultimately her Coombs DAT/C3 test returned positive for cold agglutinins. Luckily, her pneumonia tested positive for mycoplasma, thus reducing her risk of finding a concomitant malignancy that would otherwise be more likely if an infectious precipitant were not present. Some learning points from Dr. Hegarty:
Cold Agglutinin Hemolytic Anemia:
- IgM antibody is formed that binds to antigens on RBC membrane
- The antibodies are high avidity but low affinity, and better at lower temperatures (many variants with different thermal ranges).
- Activates Classical Complement Pathway (C1, C2/C4, etc.)
- Primarily extravascular hemolysis.
- Associated with:
- Mycoplasma pneumoniae infection*
- EBV infection
- CLL/SLL or other lymphoid malignancies
- Others: CMV, legionella, citrobacter, flu, varicella, IgM MGUS, other cancers (adenocarcinoma).
- Cold avoidance
- Rituximab-containing regimens if severe/refractory (takes a while)
- PLEX if hemolysis is severe/critically ill. (doesn’t last long)
- Not much role for steroids (they help in warm AIHA though)