macroovalocyten

Macroovalocytes are abnormally large, oval-shaped red blood cells observed on peripheral blood smear. They are a form of macrocyte characterized by an elongated, oval morphology rather than the usual round, biconcave disc. They are typically noted in the setting of macrocytosis, with mean corpuscular volume often elevated (commonly >110 fL).

The appearance of macroovalocytes is most closely linked to megaloblastic anemias, which arise from impaired DNA synthesis in erythroid precursors. Deficiencies of vitamin B12 or folate disrupt nuclear maturation, causing asynchronous development of nucleus and cytoplasm. The resulting large erythrocyte precursors are released into circulation, where the mature red cells can appear oversized and oval. Reticulocytosis and other factors can contribute to overall macrocytosis, but the oval shape is a characteristic feature of macroovalocytosis in megaloblastic states.

Common causes include vitamin B12 deficiency (e.g., pernicious anemia, malabsorption) and folate deficiency (e.g., inadequate intake or malabsorption). Macroovalocytes can also be observed in rarer conditions such as certain congenital dyserythropoietic anemias and other drugs that induce megaloblastic changes. They are not specific to a single disorder and may be absent in some cases of megaloblastic anemia or present in other forms of macrocytosis.

Diagnostic relevance centers on morphological clues from the smear combined with clinical and laboratory data. Macroovalocytes support a diagnosis of megaloblastic anemia but must be interpreted alongside hypersegmented neutrophils and vitamin B12/folate measurements. Management focuses on correcting the underlying deficiency, after which red blood cell morphology and indices typically improve.