Cold agglutinin disease (CAD), a sneaky condition necessary to be correctly framed

Cold agglutinin disease (CAD), a sneaky condition necessary to be correctly framed
Author: Andrea Duminuco; Giuseppe Milone; Alessandra Cupri
Category: Red Cell: Hemolytic Anemia (HA) > Autoimmune Hemolytic Anemias > Cold-active antibodies > Cold agglutinin disease (CAD)
Published Date: 03/22/2022

Here we present the case of a 37-year-old female patient with a finding of macrocytic anaemia (8.5 g/dL, MCV equal to 103 fL), not accompanied by further changes in the blood count. Laboratory tests showed an increase in LDH and a decrease in haptoglobin values. Clinically there was intermittent pain in the extremities of the body (fingers, auricles, tip of the nose). A peripheral blood smear was performed, with a regular morphological evaluation of red blood cells at small and large magnification (Figures 1A and B). At this point, a new sample was performed by placing the tube at 4 °C for an hour before serving a new peripheral smear. Morphologically, the phenomenon of self-agglutination was found, with difficulty in evaluating it due to the presence of agglutinates, polychromasia, anisocytosis and poikilocytosis (Figures 2A and B). The suspicion of cold antibody hemolytic anaemia was confirmed by detecting polyclonal cold autoantibodies, likely post-infectious diseases. In these conditions, high titers of cold agglutinins (antibodies against the erythrocyte "I" antigen) are found in about 50% of cases of infection with Mycoplasma pneumoniae, legionella, virosis. A prompt diagnosis and a correct classification of these forms of haemolytic anaemia are fundamental in guaranteeing the best treatment of this type of clinical condition, poorly responsive to conventional cortisone therapies.