A 70-year-old woman with known CLL develops sudden worsening anemia with a positive direct Coombs test. Her lymphocyte count was stable at 40,000/µL for 2 years. The most likely pathomechanism of her new anemia is:

• A Bone marrow infiltration causing erythroid aplasia
• B Microangiopathic hemolytic anemia from DIC
• C Cold agglutinin disease mediated by IgM from the neoplastic clone
• D Warm autoimmune hemolytic anemia driven by IgG autoantibodies from the neoplastic clone ✓

Explanation

CLL is the hematologic malignancy most commonly associated with warm autoimmune hemolytic anemia (WAIHA), in which the neoplastic B-cell clone produces IgG autoantibodies directed against RBC surface antigens (typically Rh antigens). The direct Coombs test (DAT) detects IgG and/or complement on the RBC surface. Cold agglutinin disease (IgM-mediated) is more characteristic of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. DIC-associated microangiopathy would show schistocytes and coagulation abnormalities.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.