Atlas of Bone Marrow pathology: Megaloblastic Anemia

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+ Bone Marrow Pathology

Megaloblastic Anemia

Introduction

Anemia which arises from abnormal DNA synthesis caused by vitamin B12 or folate deficiencis. This leads to abnormal nuclear maturation of the hematopoietic cells and ineffective erythropoiesis. The anemia caused by B12 deficiency is also called pernicious anemia (apart from anemia, other symptoms such as atrophic glossitis, atrophic gastritis and neurologic disorders are often present).

Clinical signs

macrocytic normochromic anemia
pernicious anemia: also atrophic glossitis, atrophic gastritis, neurologic disorders

Histology

Peripheral blood: normochromic macrocytic anemia, often pancytopenia, significant anisocytosis, poikilocytosis, polychromasia is absent, neutrophilic hypersegmentation, Howell-Jolly bodies, nuclei-containing erythrocytes, basophilic stippling.
Bone marrow: hypercellular with inreased erythropoiesis, which usually dominates (M:E ratio is lower than 1:1). There is an erythropietic left shift and more immature cells are present — proerythroblasts and basophilic erythroblasts, which contain abnormally large nuclei with finer chromatin. Megakaryocytes are usually larger with hyperlobated nuclei. Mature granulopoietic cells contain hypersegmented nuclei. Giant metamyelocytes are also present.

Pictures

Megaloblastic anemia, bone marrow: Megaloblastic anemia, bone marrow, HE 100x (72608)