Hypersegmented PMNs are a classic finding in which type of anemia?

• A. Megaloblastic anemia
• B. Iron deficiency anemia
• C. Aplastic anemia
• D. Hemolytic anemia

Answer: (A)

Hypersegmented PMNs point to defective DNA synthesis seen in megaloblastic anemia, most often from vitamin B12 or folate deficiency. When DNA synthesis is impaired, neutrophil precursors in the bone marrow don’t mature properly, producing megalo­blasts and neutrophils with an increased number of nuclear lobes. Neutrophils normally have a few lobes, but in megaloblastic states they frequently have five or more, which is why this finding is classic for this type of anemia.

This helps distinguish it from other anemias. Iron deficiency anemia is typically microcytic and does not show hypersegmented neutrophils; aplastic anemia involves bone marrow failure with pancytopenia and lacks this specific neutrophil change; hemolytic anemia features increased destruction with reticulocytosis rather than hypersegmented neutrophils.