Acquired Thrombotic Thrombocytopenic Purpura in a Patient with Pernicious Anemia.

Introduction. Acquired thrombotic thrombocytopenic purpura (TTP) has been associated with different autoimmune disorders. However, its association with pernicious anemia is rarely reported. Case Report. A 46-year-old male presented with blood in sputum and urine for one day. The vitals were stable. The physical examination was significant for icterus. Lab tests' results revealed leukocytosis, macrocytic anemia, severe thrombocytopenia, renal dysfunction, and unconjugated hyperbilirubinemia. He had an elevated LDH, low haptoglobin levels with many schistocytes, nucleated RBCs, and reticulocytes on peripheral smear. Low ADAMTS13 activity (<10%) with elevated ADAMTS13 antibody clinched the diagnosis of severe acquired TTP, and plasmapheresis was started. There was an initial improvement in his hematological markers, which were however not sustained on discontinuation of plasmapheresis. For his refractory TTP, he was resumed on daily plasmapheresis and Rituximab was started. Furthermore, the initial serum Vitamin B12 and reticulocyte index were low in the presence of anti-intrinsic factor antibody. So with the concomitant diagnosis of pernicious anemia, Vitamin B12 was supplemented. The rest of the immunological workups were negative. Subsequently, his symptoms resolved and his hematological parameters improved. Discussion. While pernicious anemia can masquerade as TTP, an actual association between the two can also occur and needs further evaluation and characterization.