(499) Severe Pancytopenia and Subarachnoid Hemorrhage: A Rare Case of Vitamin B12 Deficiency

Introduction: Although Vitamin B12 deficiency is a well-known nutritional deficiency, its clinical presentation can be atypical, creating diagnostic challenges. Early identification and treatment of Vitamin B12 deficiency is crucial to prevent serious hematological and neurological complications. We present a case of Vitamin B12 deficiency manifesting as severe pancytopenia leading to subarachnoid hemorrhage.

Description: A 54-year-old Nepali-speaking female presented with bilateral foot pain for one month and acute worsening headaches. She denied nausea, vomiting, visual changes, weakness, daily medications, including blood thinners, and gastric surgery. She reported eating a regular diet, including meat. She was hemodynamically stable, alert but not oriented, and had a mild antalgic gait. Labs with repeat revealed severe pancytopenia, profound macrocytosis, and a few hypersegmented neutrophils on peripheral blood smear with hemoglobin 2.4 g/dL, hematocrit 7.5%, mean corpuscular volume 150.0 fL, white blood count 0.91 K/uL, platelet < 3 K/uL requiring packed red blood cells, platelets, and cryoprecipitate transfusions. CT head showed trace acute left frontal lobe subarachnoid hemorrhage, with no recommended neurosurgical intervention. Bone marrow biopsy and flow cytometry were both negative. Hemolysis markers were positive with elevated lactate dehydrogenase and low haptoglobin. Hepatitis markers, HIV, EBV, and CMV were negative. Vitamin B12 was < 150 pg/mL, folic acid was 2.2 ng/mL, and intrinsic factor antibody was positive, indicating pernicious anemia. She was treated with Vitamin B12 intramuscular injections and folate supplementation with marked improvement in pancytopenia.

Discussion: This case emphasizes diverse features of vitamin B12 deficiency, ranging from mild symptoms to severe conditions, and highlights the importance of early recognition and management, particularly when social determinants of health, including language barriers, exist. Clinicians should maintain a high index of suspicion and consider Vitamin B12 deficiency in the differential diagnosis of patients with pancytopenia, especially after excluding bone marrow pathology, to prevent potentially life-threatening outcomes. Treatment with B12 supplementation allows for rapid recovery in this disease state.