2: Red Blood Cells- Abnormal RBC Morphology — Read

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2.1: Poikilocytosis
This page covers poikilocytosis, marked by abnormal red blood cell shapes in blood smears. It connects variations in morphology to specific clinical conditions, such as hemolytic anemias, thalassemia, myelofibrosis, and hereditary pyropoikilocytosis. The text emphasizes that while normal morphology was discussed earlier, understanding these abnormalities is crucial for diagnosing associated diseases, with promises for deeper insights into specific morphologies in future sections.
2.2: Acanthocytes (Spur Cells)
This page covers acanthocytes, abnormal red blood cells with spiky projections formed due to membrane defects affecting cholesterol and lipid balance. Their rigid structure can arise from hereditary or acquired conditions. Acanthocyte presence is linked to several clinical issues, such as abetalipoproteinemia, LCAT deficiency, liver disease, post-splenectomy, and pyruvate kinase deficiency. The page also includes references to related research and clinical implications.
2.3: Agglutination
This page covers the agglutination of red blood cells, marked by irregular clusters, differentiating it from Rouleaux formation. It results from antibody-antigen interactions and can be reversed by warming to 37°C. Auto-agglutination occurs when a patient’s RBC antigens respond with antibodies. Related medical conditions include Cold Hemagglutinin Disease, Paroxysmal Cold Hemoglobinuria, and Cold Autoimmune Hemolytic Anemia, with saline being ineffective in reversing agglutination.
2.4: Bite (Keratocyte) and Blister (Helmet) Cells
This page discusses bite cells and blister cells, two distinct types of red blood cells with unique morphological features. Bite cells have semi-circular indentations, while blister cells have cytoplasmic projections resembling vacuoles. Both types often coexist and can originate from macrophage removal of inclusions or rupture.
2.5: Dimorphic Population
This page details peripheral blood smears showing two red blood cell populations: hypochromic-microcytic and normochromic-normocytic. It connects these variations to conditions such as sideroblastic anemia and myelodysplastic syndrome, as well as treatment effects. The page highlights the importance of red cell distribution width (RDW) over 14.5% for diagnosis. References are included to validate the information on red blood cell morphology and its clinical implications.
2.6: Echinocytes (Burr Cells)
This page covers echinocytes, a type of red blood cell with evenly spaced projections. Their formation may result from the "glass effect" during blood smear preparation or specific storage conditions, and this change is reversible. Echinocytes can be seen as artifacts in smears and are linked to various clinical states, such as post-transfusion reactions and medical issues including liver disease and uremia.
2.7: Elliptocytes and Ovalocytes
This page discusses the characteristics, formation, and associated conditions of elliptocytes and ovalocytes, abnormal red blood cells shaped like cigars and eggs, respectively. It explains that elliptocytes emerge from membrane protein defects, while ovalocytes include oversized macro-ovalocytes. Hereditary elliptocytosis and ovalocytosis are highlighted, along with the mechanical weakness in erythrocyte membranes due to shell stress in circulation.
2.8: Pyknocytes
This page covers pyknocytes, atypical small red blood cells lacking central pallor and exhibiting irregular shapes. These cells, often formed due to dehydration or oxidative damage, are linked to conditions like pyruvate kinase deficiency, glucose-6-phosphate deficiency, severe hemolytic anemias, and infantile pyknocytosis, with credible sources backing the information.
2.9: Rouleaux
This page explains rouleaux formation in red blood cells, where cells stack due to high plasma proteins like fibrinogen and globulins. While it can occur naturally, pathological rouleaux in blood smears indicates underlying issues such as inflammatory disorders and multiple myeloma. Importantly, rouleaux is reversible with saline, distinguishing it from agglutination.
2.10: Schistocytes
This page covers schistocytes, fragmented red blood cells formed through mechanical damage, signaling intravascular hemolysis. It links schistocytes to conditions like Microangiopathic Hemolytic Anemia, Macroangiopathic Hemolytic Anemias, renal graft rejection, and severe burns. The page also includes references on red blood cell morphology and clinical implications.
2.11: Sickle Cells (Drepanocytes)
This page discusses sickle cells, which are malformed red blood cells caused by a genetic mutation in the β globin chain leading to abnormal hemoglobin S. These cells adopt a curved shape under low oxygen conditions due to hemoglobin S polymerizing, influenced by factors like low oxygen saturation and dehydration. It highlights related diseases, including Sickle Cell Disease and Hemoglobin SC Disease, clarifying that sickle cells do not occur in the heterozygous state.
2.12: Spherocytes
This page covers spherocytes, which are small, round red blood cells without central pallor, resulting from a partial loss of their membrane during extravascular hemolysis. It discusses hereditary spherocytosis due to membrane protein defects and related conditions like Warm Auto-Immune Hemolytic Anemia and Glucose-6-Phosphate Deficiency. The page notes that spherocytes have an increased mean corpuscular hemoglobin concentration (MCHC).
2.13: Stomatocytes
This page discusses stomatocytes, a type of red blood cell with a distinctive cup shape and central pallor due to membrane defects affecting cell volume, which can arise from hereditary conditions or factors like alcoholism and liver disease. It covers the mechanisms of stomatocyte formation, including hydrocytosis and xerocytosis, as well as their morphology, associated diseases, and clinical significance.
2.14: Target Cells (Codocytes)
This page describes target cells, which are characterized by a "bullseye" appearance due to concentrated hemoglobin and a colorless zone. Their formation is related to liver disease and can occur in high humidity as an artifact. Conditions such as hemoglobinopathies lead to uneven hemoglobin distribution and increased surface area. Target cells are associated with various diseases, including hemoglobinopathies, iron deficiency anemia, obstructive liver disease, and post-splenectomy states.
2.15: Tear Cells (Dacrocytes, Teardrops)
This page discusses teardrop-shaped red blood cells, or tear cells, which vary in size due to challenges in microcirculation. Their formation is associated with conditions like primary myelofibrosis, thalassemia, and various types of anemia. The text highlights the connection between abnormal hematopoietic tissue displacement in the bone marrow and the development of these atypical cells, supported by clinical references on their morphology and pathophysiology.

This page titled 2: Red Blood Cells- Abnormal RBC Morphology was last modified on Fri, 11 Sep 2026 16:39:54 GMT and is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Valentin Villatoro and Michelle To (Open Education Alberta) via source content that was edited to the style and standards of the LibreTexts platform.

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