SHM Converge Scientific Abstract ePoster Gallery-B12 Deficiency as a Rare Cause of Pancytopenia, Hemolytic Anemia, and Pseudo-Thrombotic Microangiopathy

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This case describes a 40-year-old woman admitted with fever and severe pancytopenia, including macrocytic anemia, neutropenia, and thrombocytopenia. Her labs also showed evidence of hemolysis, with schistocytes on peripheral smear and elevated markers consistent with microangiopathic hemolytic anemia, raising concern for thrombotic thrombocytopenic purpura (TTP), leukemia, or autoimmune hemolysis.<br /><br />However, several findings pointed toward vitamin B12 deficiency instead. The smear showed hypersegmented neutrophils, which are classic for B12 deficiency. Additional workup confirmed a low B12 level and elevated methylmalonic acid, supporting the diagnosis. Autoimmune hemolytic anemia was considered unlikely because the Coombs test was negative. Leukemia was also unlikely due to the absence of blasts, normal flow cytometry, and rapid improvement in neutrophil count after treatment. TTP was less likely because the patient had neutropenia rather than the expected isolated thrombocytopenia, and she had pancytopenia documented two months before admission.<br /><br />The case highlights that severe B12 deficiency can rarely cause hemolytic anemia with schistocytes, mimicking thrombotic microangiopathy or even acute leukemia. This can lead to diagnostic confusion because the peripheral smear may resemble a more dangerous hematologic emergency.<br /><br />The patient was treated empirically with intramuscular vitamin B12, which led to improvement in lactate dehydrogenase and ANC. She was discharged on oral B12 supplementation. At one-month follow-up, her fatigue had resolved and her blood counts had nearly normalized.<br /><br />Overall, this case emphasizes the importance of considering B12 deficiency in patients with pancytopenia and schistocytes, especially when hypersegmented neutrophils are present on smear.

Asset Subtitle

Nikhil Shamapant

Meta Tag

Author List John M. Cunningham, Lila Steinberg, Nikhil Shamapant

Category Clinical Vignettes

Concept Vitamin B12 Deficiency

Concept Pancytopenia

Concept Pseudo-thrombotic Microangiopathy

Concept Schistocytes

Concept Hypersegmented Neutrophils

Distinguished Non-Finalist

Presenter Organization University of Colorado

Presenting Author Nikhil Shamapant

Track Adult

Keywords

vitamin B12 deficiency

pancytopenia

schistocytes

macrocytic anemia

hypersegmented neutrophils

microangiopathic hemolytic anemia

thrombotic thrombocytopenic purpura

neutropenia

methylmalonic acid

intramuscular vitamin B12

Vitamin B12 Deficiency

Pancytopenia

Pseudo-thrombotic Microangiopathy

Schistocytes

Hypersegmented Neutrophils