Massive hemolysis, a rare manifestation of Mycoplasma pneumoniae infection, is due to cold agglutinins (IgM antibodies) that appear seven to ten days after the infection in around 50% to 70% of cases. Hyperleukocytosis, suggestive of bacterial or neoplastic etiologies, is also an uncommon event. We report here on the case of a 67-year-old man with Mycoplasma pneumoniae pneumonia who presented with severe anemia and leukemoid reaction as diagnosed by the bedside cold agglutinin test and measurement of anti-mycoplasma antibodies. After beginning appropriate treatment, the anemia improved significantly and the leukocyte count reduced from 56100 /mm³ to close to normal level.
Mycoplasma pneumoniae; hemolytic anemia; leukocytosis