A 30-year-old woman has thrombocytopenia, microangiopathic hemolytic anemia (schistocytes), fever, neurological symptoms, and renal impairment. The pathological mechanism involves:

• A IgG antibody-mediated platelet destruction by splenic macrophages
• B Deficiency of ADAMTS13 causing ultra-large vWF multimers, platelet microthrombi in small vessels ✓
• C Factor VIII deficiency causing failure of intrinsic coagulation
• D Complement-mediated destruction of platelets and RBCs

Explanation

This is the pentad of thrombotic thrombocytopenic purpura (TTP). ADAMTS13 is the metalloprotease that cleaves ultra-large vWF multimers secreted by endothelial cells; its deficiency (autoimmune or hereditary) allows accumulation of unusually large vWF multimers that spontaneously capture and activate platelets, forming microthrombi in capillaries and arterioles. The resulting shear forces fragment RBCs into schistocytes. Treatment is plasma exchange to replenish ADAMTS13.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.