Pseudothrombotic Microangiopathy as a Rare Presentation of Cobalamin Deficiency.

The hematological manifestations of cobalamin (vitamin B12) deficiency may range from asymptomatic to life-threatening forms. Pseudothrombotic microangiopathy is a rare but severe presentation, characterized by the presence of hemolysis and schistocytosis, that is completely reversible after vitamin supplementation. We present a challenging diagnostic approach of a 55-year-old man who presented with high hemolytic markers, pancytopenia, and schistocytes on the peripheral smear due to acquired cobalamin deficiency. Subsequent testing revealed positive anti-intrinsic factor and anti-parietal cell antibodies consistent with pernicious anemia. Cobalamin replacement led to the resolution of microangiopathic hemolysis and clinical improvement, thereby confirming the diagnosis. This case highlights the importance of early recognition of this syndrome, which is often misdiagnosed as true microangiopathic hemolytic anemia, confounding appropriate management.