7-months-old infant was admitted to the hospital for progression of lethargy, pallor and hypotonia. Pancytopenia with normocytic anemia, elevation of lactatdehydrogenase were diagnosed.
Aspiration of bone marrow was hypercellular, revealed hypersegmented neutrophils and megaloblastoid cells. Severe deficiency of vitamin B12 and sideropenia were confirmed.
After parenteral vitamin B12 administration quick improvement of clinical status and hematopoiesis was observed.