Severe vitamin B12 deficiency presenting with blast- like atypical lymphoid cells and transient HPLC studies in an infant with suspected goldenhar syndrome: a diagnostic challenge

Severe vitamin B12 deficiency in infancy is uncommon and may produce profound hematological abnormalities. Rarely, marked hematogone proliferation can mimic acute leukemia because of atypical lymphoid cells in peripheral blood. An 8-month-old exclusively breastfed male presented with recurrent severe anemia, regurgitation, and lethargy. Hemoglobin was 4.8 g/dL, with macrocytosis, low corrected reticulocyte count, and markedly reduced serum vitamin B12 (