Case Presentation: 62 y.o. Male with a family history of leukemia and a personal history of diabetes, and hypertension presented with 3 months of SOB, fatigue, and weakness. He noted his symptoms worsened with physical activity, but denied any leg swelling, orthopnea, PND, or chest pain. Denied any history of rectal bleeding, drinking, or recent viral illness. He recently had a colonoscopy performed, which was negative for malignancy. On presentation vitals were stable and physical exam was negative for any focal neurological weakness, lymphadenopathy, or petechial hemorrhages. Initial labs showed pancytopenia and a clinical picture compatible with a severe hematological problem. The white blood count was 2.6 K/uL, hemoglobin 7.6 g/dL, and platelets 88 UK/uL. The LDH was 2170 IU/L, haptoglobin <8.0 mg/dL, the absolute reticulocyte count was 1.7 and reticulocyte index was 0.8. Further biochemical investigations revealed an MCV of 105 fl, RDW of 25.8, Vitamin B-12 level 107 pg/ml, homocysteine 65 umol/L, methylmalonic acid level of 5 umol/L, and a normal folate at 10 ng/ml. Further workup of vitamin B12 deficiency revealed positive antibodies against intrinsic factor. Hematology evaluated the patient and placed the patient on intramuscular vitamin B12 replacement. A month after vitamin B12 supplementation, there was effective response to therapy in all cell lines.
Discussion: Current literature reports that vitamin B12 deficiency affects 16% of the population or 48 million Americans (1) It is the most common nutritional deficiency in the United States, affecting all ages, races, and both sexes (2). Despite this, B12 is often overlooked in health care in favor of a more recognized and more expensive to treat diagnosis. It is important to know that B12 deficiency can initially present in a variety of ways including hematological disorders. For instance, B12 deficiency can manifest as pancytopenia and is a known reversible cause of bone marrow failure that can be mistaken for acute leukemia, as was an initial concern in this case given the family history of leukemia and severity of pancytopenia. Vitamin B12 is necessary for synthesis of DNA precursors in all cell lines. Lack of vitamin B12 impairs DNA formation resulting in impaired division and enlargement of RBC’s leading to megablastic anemia, and if severe enough like in this case lead to pancytopenia. There have been several published case reports where patients have been given the preliminary diagnosis of acute leukemia, and later reversed only after subsequent flow cytometry and cytogenetic studies showed no apparent abnormalities. These workups can be expensive and ultimately unnecessary
Conclusions: B12 deficiency may mimic a variety of serious conditions including hematological, conditions. Clinicians should be aware that B12 could cause pancytopenia because it is easily diagnosed and inexpensive to treat. Early diagnosis can prevent extensive and expensive clinical workups that are not necessary
References:
1. Allen, L. H. “How Common Is Vitamin B-12 Deficiency?” American Journal of Clinical Nutrition (2009). Print.
2. Pacholok, Sally M., and Jeffrey J. Stuart. Could It Be B12? an Epidemic of Misdiagnoses. 2nd ed. Fresno, Calif.: Quill Driver, 2011. Print.