Anisopoikilocytosis

Anisopoikilocytosis is a hematologic term describing marked variation in red blood cell (RBC) size (anisocytosis) and morphology (poikilocytosis) on a peripheral blood smear. It is a descriptive finding rather than a disease entity, and its presence indicates an underlying disruption of erythropoiesis or RBC survival.

Causes are diverse and it is commonly observed in many anemias and bone marrow disorders. Associations include iron deficiency anemia, megaloblastic anemia due to vitamin B12 or folate deficiency, sideroblastic anemia, thalassemias, and various hemolytic or dyserythropoietic conditions. Severe anemia or marked erythroid stress often exaggerates anisopoikilocytosis. Specific RBC shapes may accompany the finding, such as teardrop cells, elliptocytes, burr cells, schistocytes, target cells, or spherocytes, reflecting the underlying pathology.

Pathophysiology involves heterogeneity in erythrocyte production and destruction, along with membrane and cytoskeletal abnormalities. Factors include impaired hemoglobin synthesis, altered membrane lipids, defective cytoskeletal proteins, and ineffective erythropoiesis, all contributing to a broad spectrum of RBC sizes and shapes.

Diagnosis and clinical significance: anisopoikilocytosis is a nonspecific clue that guides further workup rather than providing a single diagnosis. Evaluation typically includes a complete blood count with reticulocyte count, iron studies, vitamin B12 and folate levels, hemoglobin electrophoresis if indicated, and liver function tests. In some cases, persistent anisopoikilocytosis prompts bone marrow examination to evaluate for myelodysplastic syndromes or leukemia.

Management focuses on treating the underlying cause. This may involve iron supplementation for deficiency, vitamin B12 or folate therapy, management of hemolysis, transfusion for symptomatic or severe anemia, and supportive care as needed.