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Eosinophil _140x 128_


Monocyte _border


Neutrophil _140x 107_


Lymphocyte _140x 114_


Anisocytosis _140x 105_


Basophilic _stippling _140x 94_

Basophilic Stippling

Burr _cells _140x 112_

Burr cells

Howell -jolly _bodies _140x 104_ 

Howell Jolly bodies 

Macrocytosis _140x 93_ 


Microcytosis _140x 95_


Pencil _cells _140x 104_ 

Pencil cells 

Polychromasia _140x 106_


Sickle _cells _140x 108_ 

Sickle cells  

Target _cells _140x 92_ 

Target cells

Reactive _lymphocyte _140x 103_

Reactive (atypical) lymphocyte

Auer _rods _140x 105_ 

Auer rods

Hypersegmented _neutrophil _140x 119_ 

Hypersegmented Neutrophil (Right shift)

Toxic _granulation _140x 146_

Toxic granulation

Blood films are typically used by the laboratory to resolve unusual red cell indices, white cell differential and/or platelet findings seen upon initial (FBC) analysis. When interpreting blood films the age of the patient is important: viral illnesses can produce bizarre looking films in children. The myelodysplastic syndromes (MDS) and malignancies tend to occur in older people. If the patient is well, it may be worth repeating the film to see if any abnormalities seen initially have resolved. If the patient is unwell (or has lymphadenopathy or hepatosplenomegaly) then disease has to be excluded.

Abnormalities of Erythrocytes The red blood cell is a pink biconcave disc-shaped cell, about the size of a small lymphocyte nucleus. Normally, healthy cells are roughly the same size, shape and colour. Morphological abnormalities are rarely specific to one condition; they can occur in a range of problems. Consult table below for a list of common findings and their associated causes.

Acanthocytes are spiculated (spikey) red cells that are found in some cases of α-β-lipoproteinaemia, chronic liver disease and α-thalassaemia trait. There is also a hereditary acanthocytosis
Anisocytosis is variation in red cell size which may occur in thalassaemia, iron deficiency or megaloblastic anaemias
Basophilic stippling describes the presence of small granular bodies within the red cell cytoplasm and occurs when there is disordered and accelerated erythropoiesis so that red cells with immature cytoplasm are released into the circulation. It may be found in lead poisoning, thalassaemia or other causes of significant anaemia
Bite cells occur in G6PD deficiency and in oxidative haemolysis
Burr cells are a type of echinocyte: found in patients with uraemia
Cabot's rings are circular or figure-of-eight structures in red cells that stain red with Wright's stain and are thought to represent nuclear membrane remnants; they are found in similar conditions to Howell-Jolly bodies(see below)
Cigar cell see elliptocyte
Codocyte see target cells
Crenated cells are a type of echinocyte: most often a storage or EDTA artefact
Dacrocyte see teardrop cells
Dimorphic picture/appearance describes heterogeneity in the size of red blood cells, usually with two distinct populations. It can be found in partially treated iron deficiency, mixed deficiency anaemias (e.g. folate/B12 and iron together), following red cell transfusion or in cases of sideroblastic anaemia
Drepanocyte see sickle cells
Echinocytes are cells with many blunt spicules. They may be artefactual - see crenated cells or pathological - see burr cells
Elliptocytes occur in hereditary elliptocytosis, myeloproliferative disorder and myelodysplastic syndrome. Subtype:pencil/rod cell
Erythroblasts (normoblasts) are immature, nucleated red cells seen in the peripheral blood in leucoerythroblastic anaemia, haemolysis, hypoxia and marrow infiltration
Fragmented red cells see schistocytes
Heinz bodies are denatured haemoglobin due to oxidative damage. They are never seen in normal individuals as they are removed by the spleen. A small number may therefore be seen post-splenectomy and also with the use of anti-oxidant drugs or sulphonamides, in G6PD deficiency and with unstable haemoglobin
Howell-Jolly bodies are nuclear remnants found in red cells normally removed by the spleen and seen after splenectomy, in cases of megaloblastic and iron-deficiency anaemias and rarely in cases of leukaemia
Hypochromia is impaired staining of red cells seen commonly in iron deficiency anaemia and also in thalassaemia and sideroblastic anaemias
Hyposplenic film is a description of the collection of abnormalities found in these patients. They include Howell-Jolly bodies, target cells, occasional nucleated red blood cells, lymphocytosis, macrocytosis and acanthocytes. There may also be evidence of infectious mononucleosis, any viral infection, toxoplasmosis and drug reactions
Leptocytes see target cells
Macrocytosis is the presence of abnormally large red cells found when erythropoiesis is disordered or when red cells are released prematurely from the marrow. They occur in alcohol excess and liver disease, megaloblastic anaemia or as a consequence of haemolysis. They are also found in B12 or folate deficiency, pregnant women and newborn infants, following use of antimetabolites, hypothyroidism, chronic respiratory failure and aplastic anaemia
Mexican hat cells see target cells
Microcytosis is the presence of abnormally small red cells often found in association with hypochromia in iron deficiency anaemia. They are also seen in thalassaemia trait, congenital sideroblastic anaemia and in the anaemia of chronic disorders if these are long-standing
Mouth cell see stomatocyte
Normoblast see erythroblast
Ovalocyte see elliptocyte
Pappenheimer bodies are phagosomes, containing ferruginous granules, found in red blood cells in diseases such as sideroblastic anaemia, haemolytic anaemia and sickle cell disease. They are also found in carcinomatosis and after splenectomy. They may contribute to spurious platelet counts by electro-optical counters
Pencil cell a type of elliptocyte: occur where there is iron deficiency anaemia, thalassaemia trait and syndromes and in pyruvate kinase deficiency
Polychromasia is the heterogeneous staining of red blood cells of different ages, with younger cells appearing blue that occurs after haemorrhage, haemolysis, dyserythropoiesis and treatment with haematinics such as iron and vitamin B12
Poikilocytosis is the general term used for variation in cell shape
Reticulocytosis is the presence of >0.8–2% of total red cell count in the form of reticulocytes. See below
Rod cell see pencil cell
Rouleaux are stacked/clumped groups of red cells caused by the presence of high levels of circulating acute-phase proteins which increase red cell 'stickiness'. They are often an indicator that a patient has a high ESR and are seen in infections, autoimmune conditions, chronic inflammation, paraproteinaemia and myeloma
Schistocytes are red cells fragmented by their passage through intravascular strands of fibrin, found in cases of intravascular haemolysis, renal failure and thrombotic thrombocytopaenic purpura amongst others
Sickle cells also known as drepanocytes, are found in sickle cell anaemia and other sickle syndromes but not in sickle trait. Their name describes their shape
Spherocytes are overly-round or spheroid red cells that usually indicate active haemolysis and are also found where there is a delayed post-transfusion reaction, DIC and post-splenectomy. They are seen more rarely in cases of hereditary spherocytosis
Spur cells see acanthocytes
Stomatocyte an oval or rectangular area of central pallor, sometimes referred to as a "mouth" arises as a result of loss of concavity on one side. They can occur in liver disease, electrolyte imbalance and hereditary stomatocytosis
Target cells also known as codocytesleptocytes or mexican hat cells. They are red cells with a central area of increased staining, surrounded by a ring of hypodense staining and then a further ring of dense staining at the edge of the cell, giving an appearance akin to an archery target. This occurs as a result of the shift in equilibrium between the erythrocyte and cholesterol. They may be found in liver disease, thalassaemia or sickle-cell disease. They occur occasionally in small numbers in iron deficiency anaemia and sometimes following splenectomy
Teardrop red cells are found in myelofibrosis, metastatic marrow infiltration and myelodysplastic syndrome
Reticulocytes these are young, oversized red cells that are present when the marrow is actively producing red cells. They are the intermediary between the nucleated red blood cell and the mature red blood cell. Small numbers of reticulocytes are found in normal peripheral blood. They are usually expressed as a percentage of total red cells (see below for further details)
Increased Reticulocyte count they are present after haemorrhage, haemolysis, severe hypoxia, in polycythaemia of any cause and in marrow infiltration. Reticulocytes may rise during marrow recovery following chemotherapy or radiotherapy. They may also be seen following treatment of deficient patients with haematinics when they are a useful measure of response to the treatment
Decreased Reticulocyte count reticulocyte levels drop where there is marrow infiltration (leukaemia, myeloma, lymphoma or other malignancies) or due to marrow underactivity such as in iron, folate or B12 deficiency or due to autoimmune disease, malnutrition, uraemia, drugs, aplastic anaemia and red cell aplasia

Abnormalities of Leucocytes As with erythrocytes, each type of leucocyte has characteristics that can be identified on stained specimens allowing for an easy diagnosis to the well-trained eye. The first thing the haematologist will assess is the absolute number of white cells (see FBC record, link in introduction). If the count is low, subsequent stain and diagnosis may be tricky. If the count is high, an assessment is made of which cell type predominates (i.e. lymphocytes versus granulocytes) and any abnormal cells; - consult the table below for a list of common findings and their associated causes.

Atypical lymphocytes see reactive lymphocytes
Auer rods are seen in myeloblasts and are pathognomic of acute myeloid leukaemia
Blast cells are abnormal, immature, nucleated precursor white cells pushed out from the marrow into the circulation by processes such as myelofibrosis or leukaemic infiltration
Hairy cells have fine, irregular pseudopods and immature nuclear features. They are seen only in hairy cell leukaemia
Hypersegmented neutrophils see right shift
Myelocytes,promeyelocytes,metamyelocytes are immature white cells seen in a leucoerythroblastic picture (see below)
Left shift describes immature white blood cells that are released from the marrow when there is a cause of marrow outpouring, typically due to infection
Leucoerythroblastic anaemia/ picture describes the presence of immature cells such as myeloblasts and normoblasts in the film. It is seen in cases of marrow infiltration - for example in metastatic malignancy, prolonged hypoxia or severe infection
Leukaemoid reaction is a severe, reactive leucocytosis, usually consisting of granulocytes (polymorphonucleocytes). It is seen after burns, in cases of severe infection, following an acute haemolysis or prolonged hypoxia
Pelger-Huet anomaly describes bilobed neutrophils which may be hereditary (when the neutrophils are functionally normal) or acquired, e.g. myelodysplastic syndrome
Reactive lymphocytes seen in infectious mononucleosis
Right shift is characterised by the presence of hypersegmented polymorphonucleocytes (>5 lobes to their nucleus), seen in liver disease, uraemia and megaloblastic anaemia
Smear cells are lymphocytes whose cell membranes have ruptured in preparation of the blood film: seen in chronic lymphocytic leukaemia
Toxic granulation is where coarse granules are seen in neutrophils. They may be seen post-operatively, in inflammatory disorders and in severe infection

Abnormalities of the Platelets Clumping is an in vitro artefact in some individuals and results in spurious blood analyser report of thrombocytopaenia. The in vivo content is normal and the platelets work well. Even a small blood clot in the EDTA bottle will affect the result. Taking blood into citrate or heparin will reveal normal platelet counts.

Giant platelets these occur in essential thrombocytopaenia. They result in a raised platelet distribution width (the indicator of the range in platelet size in a blood sample) unlike the normal platelet distribution width seen in reactive thrombocytosis, where there is an increased platelet count but normal sized platelets
Satellitosis describes platelets encircling a neutrophil. It occurs when a patient has a serum factor that reacts to the anticoagulant EDTA

Parasites in the Blood film

Blood films are useful for the diagnosis of:-

  • Babesiosis
  • Malaria
  • Microfilaria
  • Trypanosomiasis

Some diseases require bone marrow aspiration (e.g. Leishmaniasis). However, development of sensitive monoclonal antibody techniques has made diagnosis on a peripheral blood film more of a dying art. The notable exception to this is in the diagnosis of malaria where a peripheral smear study remains the gold standard.

Last updated: 17 February 2015