RBC Morphology-Introduction, Types, Clinical Significance

Introduction

Table of Contents

RBC morphology examines red blood cell shape, size, and color. Moreover, it provides insights into hematologic health. Additionally, abnormal features suggest underlying diseases. Furthermore, clinicians use morphology to guide diagnosis. Consequently, it is crucial in routine blood evaluations.

Fig. These red cells in the urine appear shrunken and have multiple short, uniform projections on their surfaces. They are commonly described as “crenated” or “echinocyte‐like” RBCs, which often result from a hypertonic or otherwise unfavorable environment in the urine as shown in this image.

Types

Some common types of RBC morphology are as follows-

Normocytic Normochromic RBCs

Normocytic cells have a normal size. Moreover, they carry normal hemoglobin. Consequently, they indicate healthy erythropoiesis.

Microcytic Hypochromic RBCs

Microcytic cells are smaller than usual. Additionally, they have reduced hemoglobin content. Consequently, they often signal iron deficiency or thalassemia.

Macrocytic RBCs

Macrocytic cells are larger than normal. Furthermore, they occur in vitamin B12 or folate deficiency. Consequently, they suggest megaloblastic anemia.

Anisocytosis

Anisocytosis describes significant size variation. Moreover, it reflects heterogeneous red cell production. Consequently, it appears in many anemias.

Poikilocytosis

Poikilocytosis indicates abnormal cell shapes. Additionally, it occurs in various pathological conditions. Furthermore, it requires thorough evaluation.

Spherocytes

Spherocytes are round and lack central pallor. Moreover, they are common in hereditary spherocytosis. Consequently, they imply membrane defects.

Elliptocytes

Elliptocytes display an oval shape. Additionally, they suggest hereditary elliptocytosis. Furthermore, they may also indicate iron deficiency anemia.

Target Cells

Target cells show a central area with a bull’s-eye appearance. Moreover, they appear in liver disease and thalassemia. Consequently, they indicate abnormal hemoglobin distribution.

Schistocytes

Schistocytes are fragmented, irregular red cells. Additionally, they result from mechanical destruction. Furthermore, they often indicate microangiopathic hemolytic anemia.

Stomatocytes

Stomatocytes present with a slit-like central pallor. Moreover, they occur in hereditary stomatocytosis and liver disease. Consequently, they reflect altered membrane integrity.

Burr Cells (Echinocytes)

Burr cells exhibit spiny projections on their surface. Additionally, they often appear in uremia. Furthermore, they may result from enzymatic disturbances.

Teardrop Cells (Dacrocytes)

Teardrop cells resemble teardrops. Moreover, they appear in myelofibrosis and marrow infiltration. Consequently, they signal severe hematologic stress.

Fragmented Cells

Fragmented cells represent broken or disrupted red cells. Additionally, they occur in severe hemolysis. Furthermore, they demand prompt clinical attention.

Basophilic Stippling

Basophilic stippling shows fine blue granules within cells. Moreover, it occurs in lead poisoning and thalassemia. Consequently, it reflects residual ribosomal material.

Clinical Significance

Abnormality	Description	Significance
1. Hypochromatic cell	Increased central pallor area (>1/3)	•Iron Deficiency Anemia •Thalassemia •Sideroblastic anemia •Anemia due to chronic disease
2. Polychromasia	An increased number of blue-gray RBCs, or polychromatophils, on a routine PBS examination	A condition where there are too many immature RBCs (polychromatophilic cells) in the blood due to •Anemia •Bone marrow injury •Hemolysis, or the destruction of RBCs faster than the body can replace them •Marrow infiltration
Anisoctosis	Different sizes of RBCs	In various anemia
1. Macrocytosis	>8 μm in diameter of RBCs	•Folate and Vitamin-B12 deficiency anemia •Alcoholism •Liver Diseases
2. Microcytotosis	<6.5 μm in diameter of RBCs	•Thalassemia •Iron Deficiency anemia •Anemia of chronic diseases
Variation in the shape of RBCs	Variation in the shape of RBCs
1. Spherocytosis	Absence of central pallor	•ABO hemolytic disease of the newborn •Hemolytic anemia due to warm antibody •Hereditary spherocytosis
2. Pencil cell	Tear drop-like cells	Iron Deficiency anemia
3. Sickle cell	Elliptical, crescent, or boat-shaped cells	Sickle cell diseases
4. Target cell (leptocytes)	Unstained ring in RBCs	•Thalassemia •Sickle cell diseases •Liver diseases
5. Schistocytes	Irregularly contracted red cell fragments	•Disseminated Intravascular Coagulation (DIC) •Severe burns
6. Teardrop cells	Tear drop like cells	•Seen in marrow infiltration ( due to fibrosis, granulomatous inflammation, hematologic or metastatic malignancy) •Splenic abnormalities •Megaloblastic anemia •Thalassemia
7. Acanthocytes	Irregularly crenated RBCs	Teardrop like cells
8. Burr cells (Echinocytes)	Small cells or cell fragments with spicules	•Acute blood loss •Uremia •Pyruvate kinase disease
9. Howell-jolly bodies	Darkly stained spherical bodies (nuclear remnants) in RBCs	•Splenectomy •Functional asplenia •Megaloblastic anemia •Severe hemolytic anemia
10. Basophilic stippling	Small blue dots in red blood cells	•Lead poisoning •Infections •Thalassemia

Table: RBCs abnormality and clinical significance

Clinicians analyze morphology to diagnose various anemias. Moreover, microcytosis often signals iron deficiency. Additionally, macrocytosis may indicate vitamin B12 or folate deficiency. Furthermore, poikilocytosis suggests bone marrow stress or hemolytic conditions—consequently, abnormal morphology guides treatment decisions and monitoring.

Fog. Cigar or pencil-shaped RBC on peripheral blood smear (PBS)

Keynotes

Firstly, RBC morphology examines red blood cell shape, size, and color.
Moreover, normal RBCs appear as biconcave disks with uniform size.
Additionally, microcytosis indicates smaller cells, often due to iron deficiency.
Furthermore, macrocytosis shows larger cells, commonly seen in vitamin B12 deficiency.
Also, anisocytosis reflects significant variation in cell sizes.
Consequently, poikilocytosis signifies abnormal cell shapes associated with various anemias.
Moreover, target cells display a bull’s-eye appearance and occur in liver disease.
Similarly, spherocytes lack central pallor, suggesting membrane defects.
Additionally, elliptocytes exhibit an oval shape, often seen in hereditary conditions.
Furthermore, schistocytes result from mechanical fragmentation and indicate hemolysis.
Also, burr cells have spiny projections, frequently observed in uremia.
Moreover, teardrop cells appear in bone marrow infiltration or myelofibrosis.
Additionally, basophilic stippling shows blue granules, hinting at lead poisoning.
Finally, these morphological features guide clinicians in diagnosing hematologic disorders.

RBC Morphology-Introduction, Types, Clinical Significance, and Keynotes