Introduction: Although vitamin B12 deficiency is a well-known cause of hematological and neuropsychiatric illness, the presentation of combined severe pancytopenia, demyelination and prominent psychiatric impairment is rare.
Case presentation: We present a case of a previously healthy 55-year-old East African man with severe vitamin B12 deficiency (serum vitamin B12 22pmol/L) secondary to pernicious anemia. He had a severe hypoproliferative megaloblastic anemia with hemolysis (hemoglobin 61g/L, mean corpuscular volume 99fL, reticulocytes 0.8%, haptoglobin undetectable), leukopenia (2.7×109/L), thrombocytopenia (96×109/L), ataxia with central demyelination, and megaloblastic madness. The patient's anemia, myelopathy and psychiatric condition responded well to parenteral vitamin B12 replacement therapy, with significant improvement seen within weeks.
Conclusion: Hematological manifestations of vitamin B12 deficiency are typically inversely correlated with the presence and severity of neuropsychiatric impairment. Although uncommon, a presentation with severe hematological and neuropsychiatric disease can occur, as illustrated by this case. Its presence may help guide diagnosis as well as provide clinically important prognostic information.