**3.3 Anisochromia/polychromasia**

Anisochromia depicts increased or decreased haemoglobinization of the red cells. In hypochromic red cells, the central pallor exceeds one third of the diameter. Hypochromia usually follows microcytosis, as seen in iron deficiency states. Hyperchromia (increased haemoglobinisation) is associated with shape abnormalities such as (micro)-spherocytes and sickled red cells. Increased haemoglobinization obliterates central pallor. Occasionally, severe hypochromia is associated with macrocytic red cells, termed leptocytes. Leptocytes are seen in severe iron deficiency, thalassemia and liver diseases [14]. Polychromasia on PBF suggests in-vivo reticulocytosis. Literally, polychromasia means 'many colours', i.e. the red cells bear another shade of colour than pink (eosinophilic). Polychromatic red cells are macrocytic (young red cells) and have a bluish tinge. The blue tinge denotes the presence of rRNA which eventually undergo the pitting action of the spleen to become mature circulating red cells [1]. Normally, polychromatic red cells are not obvious on PBF—adult reticulocyte population is about 0.5–2.5% [3]. However, polychromatic red cells in excess of 1–2% in the periphery should be considered significant since normal daily rate of red cell turnover is about 1–2% [16]. In situations of acute haemorrhage, haemolysis, and high altitude, hypoxia induces increased erythroid activity, hence polychromasia. Polychromasia is also seen in extramedullary haemopoiesis due to myeloid metaplasia in reticulo-endothelial tissue. Following haematinic therapy, polychromatic red cells are seen as a response to treatment of micronutrient deficiency [1].

Similarly, in severe situations causing marrow stress, nucleated red cells (erythroblastosis) exit the bone marrow prematurely in order to compensate. Notable causes of erythroblastosis (or normoblastemia) include severe anaemia, asplenic/ hyposplenic state as in sickle cell disease, severe hypoxia, marrow replacements or infiltrations and extramedullary haemopoiesis [17, 18]. In neonates, nucleated red cells are normally seen in the periphery [15].

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*Erythrocyte Morphology and Its Disorders DOI: http://dx.doi.org/10.5772/intechopen.86112*

Irreversibly sickled red cells

Target red cells (codocytes) Target cells (codocytes, Mexican hat cells)

Basket cells (half ghost cells/

Teardrop red cell (dacrocytes,

Fragmented red cells (schistocytes, helmet cells,

keratocytes)

blister cells)

lacrymocytes)

**Table 3.**

(drepanocytes)

**Red cell shapes Differential diagnosis**

Pencil cells Iron deficiency

Elliptocytes Hereditary elliptocytosis (>25%)

**3.4 Other red cell abnormalities**

*Red cell shape anomalies and associated diseases.*

pyrimidine 5′ nucleotidase deficiency [1, 10, 20].

Other morphologic abnormalities include presence of inclusion bodies and pathologic distribution of red cells on the smear. A mature erythrocyte lacks inclusion bodies. Red cell inclusion bodies include nuclear products RNA/DNA, haemoglobin or iron pigments. Some, such as haemoglobin H inclusions and Heinz bodies can only be appreciated with supravital staining. Red cell inclusions result from oxidant stress, severe infections and dyserythropoiesis (maturation defects). Basophilic stipplings or punctuate basophilia are denatured RNA fragments dispersed within the cytoplasm. Basophilic stipplings may be fine, blue stipplings or coarse granules. They are non-specific and are generally related to disorders in haem biosynthetic pathways [1, 19]. Differentials include haemoglobinopathies (thalassemias), lead or arsenic poisoning, unstable haemoglobins, severe infections, sideroblastic anaemia, megaloblastic anaemia and a rare inherited condition,

Stomatocytes Artefact (due to slow drying in humid environment), liver disease,

Bite cells (degmacytes) G6PD deficiency, oxidative stress, unstable haemoglobin's, congenital

Spherocytes Hereditary spherocytosis, ABO incompatibility, autoimmune haemolytic anaemia (warm antibody type), severe burns

Heinz body anaemia

Sickle cell syndromes (SS, SC, S-β-thalassemia)

Sickle cell disease, haemoglobin C trait, haemoglobin CC disease, thalassemia's, iron deficiency, liver disease (cholestasis), asplenia

Thrombotic micro-angiopathic haemolytic anaemias such as disseminated intravascular coagulopathy (DIC), thrombotic thrombocytopenic purpura, haemolytic uraemic syndrome.

alcoholism, Rh-null disease, obstructive lung disease

Oxidant damage, G6PD deficiency, unstable haemoglobin's

Idiopathic myelofibrosis, myelophthisic anaemia, thalassemia's

Clinically insignificant, fine basophilic stippling may be associated with polychromasia/accelerated erythropoiesis/reticulocytosis. Coarse stipplings are clinically significant and indicates impaired haemoglobin synthesis as seen in megaloblastic anaemia, thalassemias, sideroblastic anaemias and lead poisoning [1, 19]. Unlike other basophilic inclusions such as Howell jolly bodies and Pappenheimer bodies which tend to be displaced to the periphery, basophilic stipplings are diffusely dispersed throughout the red cell cytoplasm. Howell jolly bodies (**Figure 3**) are DNA remnants seen in post-splenectomy patients, anatomical or functional asplenia. Siderotic granules or Pappenheimer bodies appear purple on Romanowsky stain, blue on Perl's stain and are seen in disorders of iron utilization like sideroblastic anaemias. Parasites such as *Plasmodium* spp. or *Babesia* spp. may also be seen on peripheral blood smear [21]. Both parasites invade the red cells. Their identification requires

**Figure 2.** *(4) Tear drop red cell.*


#### **Table 3.**

*Erythrocyte*

**3.3 Anisochromia/polychromasia**

to treatment of micronutrient deficiency [1].

cells are normally seen in the periphery [15].

cells may be caused by poor fixation and high humidity in the laboratory ambience. Artefactual tear drop cells should be suspected if the tails line up in the same direction. **Table 3** itemizes common poikilocytes and its differentials [1, 5, 12–15].

Anisochromia depicts increased or decreased haemoglobinization of the red cells. In hypochromic red cells, the central pallor exceeds one third of the diameter. Hypochromia usually follows microcytosis, as seen in iron deficiency states. Hyperchromia (increased haemoglobinisation) is associated with shape abnormalities such as (micro)-spherocytes and sickled red cells. Increased haemoglobinization obliterates central pallor. Occasionally, severe hypochromia is associated with macrocytic red cells, termed leptocytes. Leptocytes are seen in severe iron deficiency, thalassemia and liver diseases [14]. Polychromasia on PBF suggests in-vivo reticulocytosis. Literally, polychromasia means 'many colours', i.e. the red cells bear another shade of colour than pink (eosinophilic). Polychromatic red cells are macrocytic (young red cells) and have a bluish tinge. The blue tinge denotes the presence of rRNA which eventually undergo the pitting action of the spleen to become mature circulating red cells [1]. Normally, polychromatic red cells are not obvious on PBF—adult reticulocyte population is about 0.5–2.5% [3]. However, polychromatic red cells in excess of 1–2% in the periphery should be considered significant since normal daily rate of red cell turnover is about 1–2% [16]. In situations of acute haemorrhage, haemolysis, and high altitude, hypoxia induces increased erythroid activity, hence polychromasia. Polychromasia is also seen in extramedullary haemopoiesis due to myeloid metaplasia in reticulo-endothelial tissue. Following haematinic therapy, polychromatic red cells are seen as a response

Similarly, in severe situations causing marrow stress, nucleated red cells (erythroblastosis) exit the bone marrow prematurely in order to compensate. Notable causes of erythroblastosis (or normoblastemia) include severe anaemia, asplenic/ hyposplenic state as in sickle cell disease, severe hypoxia, marrow replacements or infiltrations and extramedullary haemopoiesis [17, 18]. In neonates, nucleated red

**12**

**Figure 2.**

*(4) Tear drop red cell.*

*Red cell shape anomalies and associated diseases.*

#### **3.4 Other red cell abnormalities**

Other morphologic abnormalities include presence of inclusion bodies and pathologic distribution of red cells on the smear. A mature erythrocyte lacks inclusion bodies. Red cell inclusion bodies include nuclear products RNA/DNA, haemoglobin or iron pigments. Some, such as haemoglobin H inclusions and Heinz bodies can only be appreciated with supravital staining. Red cell inclusions result from oxidant stress, severe infections and dyserythropoiesis (maturation defects). Basophilic stipplings or punctuate basophilia are denatured RNA fragments dispersed within the cytoplasm. Basophilic stipplings may be fine, blue stipplings or coarse granules. They are non-specific and are generally related to disorders in haem biosynthetic pathways [1, 19]. Differentials include haemoglobinopathies (thalassemias), lead or arsenic poisoning, unstable haemoglobins, severe infections, sideroblastic anaemia, megaloblastic anaemia and a rare inherited condition, pyrimidine 5′ nucleotidase deficiency [1, 10, 20].

Clinically insignificant, fine basophilic stippling may be associated with polychromasia/accelerated erythropoiesis/reticulocytosis. Coarse stipplings are clinically significant and indicates impaired haemoglobin synthesis as seen in megaloblastic anaemia, thalassemias, sideroblastic anaemias and lead poisoning [1, 19]. Unlike other basophilic inclusions such as Howell jolly bodies and Pappenheimer bodies which tend to be displaced to the periphery, basophilic stipplings are diffusely dispersed throughout the red cell cytoplasm. Howell jolly bodies (**Figure 3**) are DNA remnants seen in post-splenectomy patients, anatomical or functional asplenia. Siderotic granules or Pappenheimer bodies appear purple on Romanowsky stain, blue on Perl's stain and are seen in disorders of iron utilization like sideroblastic anaemias.

Parasites such as *Plasmodium* spp. or *Babesia* spp. may also be seen on peripheral blood smear [21]. Both parasites invade the red cells. Their identification requires
