Thrombotic Thrombocytopenic Purpura: The Daily PANCE Blueprint

The answer is C. Thrombotic thrombocytopenic purpura

Microangiopathic hemolytic anemia plus thrombocytopenia with normal coagulation studies is thrombotic thrombocytopenic purpura, and it is a true hematologic emergency — untreated mortality approaches 90%, and treatment drops it below 20%. The mechanism explains every number on the panel. TTP is caused by a deficiency of ADAMTS13, the protease that cleaves ultra-large von Willebrand factor multimers; most adult cases are acquired, from an autoantibody. Without that scissors, giant vWF multimers stay anchored to the endothelium and snag passing platelets, so platelet-rich microthrombi form throughout the small vessels. Platelets are consumed, which is the thrombocytopenia. Red cells are physically sheared as they force past those strands, which produces the schistocytes, the high LDH, the undetectable haptoglobin, and the indirect hyperbilirubinemia — hemolysis that is mechanical, not immune, which is exactly why the Coombs test is negative. The classic pentad is fever, microangiopathic hemolytic anemia, thrombocytopenia, neurologic changes, and renal dysfunction — but it appears in full in only a minority, and waiting for all five is a documented way to let a patient die. Thrombocytopenia plus schistocytes with no other explanation is enough to act. The normal PT, aPTT, and fibrinogen are the single most useful discriminator from DIC. Treatment is urgent plasma exchange, which both removes the autoantibody and replaces ADAMTS13, plus corticosteroids, with rituximab and caplacizumab added in many protocols. The critical don’t: do not transfuse platelets. In a platelet-consumption thrombotic state that is fuel on the fire and can precipitate further thrombosis — reserve them for life-threatening bleeding. Separating the distractors: immune thrombocytopenic purpura gives isolated thrombocytopenia in a well patient with a normal hemoglobin and no schistocytes or hemolysis; disseminated intravascular coagulation also produces schistocytes but consumes clotting factors, so the PT and aPTT are prolonged, the fibrinogen is low, and D-dimer is high, and it occurs in the setting of sepsis, trauma, malignancy, or obstetric catastrophe; autoimmune hemolytic anemia is a Coombs-positive hemolysis with spherocytes rather than schistocytes and normal platelets; and heparin-induced thrombocytopenia requires heparin exposure, drops the platelets by more than 50% around days 5 to 10, and causes thrombosis rather than a microangiopathic hemolytic picture. One more to hold alongside it: hemolytic uremic syndrome looks similar but hits children after a Shiga toxin–producing E. coli diarrheal illness, with renal failure dominating and neurologic signs minimal.