A 30-year-old woman presents with purpura, microangiopathic hemolytic anemia, thrombocytopenia, fever, and neurological symptoms. Peripheral smear shows schistocytes. ADAMTS13 activity is less than 5%. The diagnosis is:

• A Hemolytic uremic syndrome (HUS)
• B Disseminated intravascular coagulation (DIC)
• C Evans syndrome
• D Thrombotic thrombocytopenic purpura (TTP) ✓

Explanation

TTP is caused by deficiency (acquired or congenital) of ADAMTS13, the metalloprotease that cleaves ultra-large von Willebrand factor (vWF) multimers. Without ADAMTS13, large vWF multimers accumulate on endothelial surfaces, causing platelet microthrombi, microangiopathic hemolytic anemia (schistocytes), and thrombocytopenia. HUS typically follows Shiga toxin-producing E. coli infection and predominantly causes renal failure; DIC shows prolonged PT/aPTT and reduced fibrinogen; Evans syndrome is combined autoimmune hemolytic anemia and thrombocytopenia.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.