Cold agglutinin syndrome (CAS) is a rare subset of autoimmune hemolytic anemia (AIHA) and can be classified as either primary or secondary. Secondary cold agglutinin disease has been associated with both viral and bacterial pathogens with the most common bacterial pathogen being
Mycoplasma pneumoniae
.
Legionella
pneumonia is a well-known causative agent for community-acquired pneumonia that can lead to a severe disease requiring hospitalization that is rarely associated with AIHA. We highlight the importance of recognizing
Legionella
pneumonia as a causative pathogen for CAS.