hematology and oncology
Megaloblastic Macrocytic Anemias
Nonmegaloblastic macrocytosis
 100 fL) anemias due to Vitamin B12 Deficiency or Macrocytosis due to excess RBC membrane occurs in patients with chronic liver disease when cholesterol esterification is defective. Macrocytosis with mean corpuscular volume of about 100 to 105 fL can occur with chronic alcohol use in the absence of folate deficiency. Mild macrocytosis can occur in Aplastic Anemia , especially as recovery occurs. Macrocytosis is also common in Nonmegaloblastic macrocytosis is suspected in patients with macrocytic anemias when testing excludes vitamin B12 deficiency or folate deficiency. The large oval RBCs (macro-ovalocytes) on peripheral smear and the increased RBC distribution width that are typical of classic megaloblastic anemia may be absent. If nonmegaloblastic macrocytosis is unexplained clinically (eg, by the presence of chronic liver disease or alcohol use) or if Myelodysplasia and Iron-Transport Deficiency Anemia is suspected, bone marrow examination and cytogenetic analysis may be done. In nonmegaloblastic macrocytosis, the marrow is not megaloblastic, but in myelodysplasia and advanced liver disease there are megaloblastoid RBC precursors with dense nuclear chromatin that differ from the usual fine fibrillar pattern in megaloblastic anemias. 