A 55-year-old woman presents with petechiae and gum bleeding. CBC reveals platelet count of 8,000/µL with normal WBC and hemoglobin. Peripheral smear shows large platelets. PT and aPTT are normal. Bone marrow shows increased megakaryocytes. Anti-platelet IgG antibodies are detected. The bleeding in this condition is primarily due to:

• A Consumption of platelets by fibrin thrombi in microvasculature
• B Opsonization of platelets by IgG leading to Fcγ receptor-mediated phagocytosis in the spleen ✓
• C Deficiency of von Willebrand factor cleaving protease ADAMTS13
• D Intrinsic platelet granule deficiency impairing aggregation

Explanation

Immune thrombocytopenic purpura (ITP) is caused by autoantibodies (predominantly IgG) directed against platelet surface glycoproteins (most commonly GPIIb-IIIa and GPIb-IX). Opsonized platelets are recognized by Fcγ receptors on splenic macrophages and undergo phagocytosis, reducing platelet lifespan to hours. Reactive megakaryocytic hyperplasia in the marrow reflects compensatory thrombopoiesis. ADAMTS13 deficiency causes TTP; microangiopathic consumption occurs in TTP/HUS; granule defects are seen in storage pool disorders.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.