Abstract
Vitamin B12 deficiency in children can cause megaloblastic anemia, poor growth, and increased chances of infections. It is an important reversible cause of bone marrow suppression which at the time of presentation can mimic hematological malignancy. Therefore, it should be considered as a differential diagnosis in cases suspected of acute leukemia. We report a case of 14 months old child who had atypical presentation of vitamin B12 deficiency. He had chronic fever, decreased feeding and increased paleness for one year. Pancytopenia with severe anemia was present along with 19% reactive/atypical cells in peripheral blood smear suggesting acute leukemia. However, bone marrow aspiration and biopsy showed features of megaloblastic anemia. Vitamin B12 level measured was very low and treatment with cyanocobalamin caused drastic improvement in the child's condition.