A 32-year-old woman reported to the clinician with “her face” as shown in the picture below. On physical examination, she appears pale and has slightly yellow sclerae and an enlarged spleen. Blood tests reveal severe anemia and mild, mostly unconjugated, hyperbilirubinemia. Coombs test is positive at 37 C but negative at 0-4 C. This patient developed anemia because of?
A. Bone marrow aplasia.
B. IgG directed against red blood cells.
C. IgM directed against red blood cells.
D. Renal failure.
The rashes on face as shown in the picture above mimics butterfly rash which is most commonly seen in cases of SLE.
Since the Coombs test is positive at warm temperature (37 C), the antibody is a warm agglutinin.
Warm agglutinins are virtually always of IgG type and may be triggered by a variety of disorders, including lymphomas, drugs, and autoimmune diseases such as SLE. IgG-coated red cells are then sequestered by the spleen, where hemolysis occurs, thus explaining splenomegaly.
By contrast, cold agglutinins are IgM and can be demonstrated by Coombs test at cold temperature (0-4 C).
Cold agglutinins are usually triggered by Mycoplasma pneumoniae infection or lymphomas.