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Case 224 - Discussion

Uploaded: 2011-10-18, Updated: 2011-10-18


The patient was found to have vitamin B12 deficiency.


Megaloblastic Anemia

  • The marrow in megaloblastic anemia may show prominent erythroid hyperplasia with variable degrees of granulocytic dysplasia, which may resemble acute leukemia or myelodysplastic syndrome. Clinic history and additional laboratory studies may be required to look for evidence of nutritional deficiency.

  • This case show macrocytic anemia with marked megaloblastic erythroid hyperplasia in the marrow with frequent giant bands. Megaloblastic red cells exhibit dramatic maturation differences between the nucleus and cytoplasm. 

  • Megaloblastic changes have to be differentiated from megaloblastiod changes. The nuclear chromatin is more delicate and less dysplastic than that in megaloblastiod changes.  Megaloblastoid red cells show more prominent dyssynchrony, more clumped chromatin, and much coarser chromatin strands.  The clear spaces between the dense chromatin strands (euchromatin) are more prominent in megaloblastoid nuclei. Besides showing abnormal maturation compared to the cytoplasm, megaloblastoid red cells may exhibit more ominous and distinctly neoplastic morphology; the nucleus may be enlarged, grotesquely shaped, lobulated, fragmented, or multinucleated.  The cytoplasm may be vacuolated and contain multiple Howell-Jolly bodies or exhibit coarse basophilic stippling.  If the red cell is severely dysplastic, a PAS stain may show clumped cytoplasmic positivity.  Megaloblastoid and dysplastic nucleated red cells are found in many different conditions, including DiGuglielmo’s syndrome, acute leukemias, myelodysplasia, myeloproliferative neoplasm, and congenital dyserythropoietic anemias.  Megaloblastoid change and lesser degrees of dysplasia may also develop after exposure to certain toxins, antibiotics, and antimetabolites, and with excess alcohol consumption.