Two cases of primary cold agglutinin disease associated with megaloblastic anemia

Area of Science:

• Hematology
• Immunology
• Internal Medicine

Background:

• Primary cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia.
• Megaloblastic anemia is often caused by vitamin B12 deficiency.
• The simultaneous occurrence of primary CAD and megaloblastic anemia is not well-documented.

Purpose of the Study:

• To report two cases of primary CAD associated with megaloblastic anemia in elderly Japanese patients.
• To discuss the potential pathophysiological link between these two hematological conditions.
• To raise clinical awareness regarding the possible co-occurrence of autoimmune hemolytic anemia and megaloblastic anemia.

Main Methods:

• Case report of two elderly male patients.
• Diagnosis of primary CAD based on high cold agglutinin titers and monoclonal IgM-kappa.
• Diagnosis of megaloblastic anemia confirmed by vitamin B12 deficiency.

Main Results:

• Both patients presented with primary CAD and vitamin B12 deficiency megaloblastic anemia.
• High cold agglutinin titers and monoclonal IgM-kappa were observed.
• One patient responded to rituximab, and both received vitamin B12 supplementation.

Conclusions:

• The association of primary CAD and megaloblastic anemia, while potentially incidental, may be linked to autoimmune mechanisms.
• Autoantibodies in CAD could target gastric parietal cells or intrinsic factor, leading to vitamin B12 malabsorption.
• Clinicians should consider screening for megaloblastic anemia in patients diagnosed with primary CAD.