Interpreting Blood Films

A blood film looks at our three cell types (erythrocytes, leukocytes & platelets) under a microscope to identify any abnormalities to give visual clues regarding the functional state of the bone marrow & any systemic diseases.

You should treat this article as a reference for where you can read up on differentials based on the blood film reports you read.

Whilst reviewing a blood film seems like a job specifically for a haematologist, being able to interpret the report of a peripheral blood film can help support your clinical assessment. As a doctor, you can correlate what you see in front of you with the blood film report much like how you’d interpret a chest x-ray or the trend in inflammatory markers.

Everything in context!

  • Unfortunately, there are hundreds of different appearances and many are non-specific or multifactorial
  • Therefore, upon reviewing the report consider the long list of differentials listed below & apply this to your clinical assessment of the patient in front of you
  • Important factors include the age & whether the patient is clinically well
    • Viral illness can cause very odd appearances in children’s blood films
    • In an otherwise well patient, an abnormal appearance could be artefactual & simply may need repeating
    • Older patients or those with lymphadenopathy/hepatosplenomegaly with an abnormal film are far more concerning of myelodysplastic syndromes or malignancy

 Whenever in doubt, a call to a haematologist can help makes things a lot clearer.

Interpretation

First, look at the Full Blood Count (FBC) – this also may be known as a complete blood count or CBC. Here is a list of common abbreviations and their meaning:

AbbreviationResult NameExplanation
RBCRed Blood CountTotal RBC count
WBCWhite Blood CountTotal WBC Count
HgbHaemoglobinGrams of Haemoglobin per decilitre (g/dL)
HctHaematocritThe proportional volume of blood occupied by RBCs
MCVMean Corpuscular VolumeMean RBC volume (i.e. their average size)
MCHMean Cell HaemoglobinAmount of haemoglobin per RBC
“Hyperchromic/hypochromic”
(Does not factor in the size of the RBC)
MCHCMean Cell Haemoglobin ConcentrationThe concentration of haemoglobin per unit of RBC volume.
(Chromia linked to cell size – more accurate result if MCV is abnormal)
RDWRed Cell Distribution WidthThe variation in RBC size
PltPlateletsTotal Platelet Count
MPVMean Platelet VolumeMean platelet volume (i.e. size)
PDWPlatelet Distribution WidthThe variation in platelet size

The report usually then comments on the appearance of each cell type and then finally any other abnormalities.

1. Erythrocytes (Red Blood Cells)
• The size, shape, membrane changes, colour and stippling are noted, as well as any inclusion bodies e.g. Howell – Jolly or parasites.
• Other abnormalities such as red cell rouleaux, red cell nucleation and the occurrence of reticulocytes.
2. Leukocytes (White Blood Cells)
• General observations such as number and morphology are described, as well as certain abnormalities including such as toxic granulation or dysplastic changes.
• Presence of abnormal cells is very important e.g. leukaemic blast cells
3. Platelets
• The number, size and shape are commented on.

Erythrocytes

Normal, healthy erythrocytes (RBCs) are pink, biconcave discs, roughly all the same size, shape and colour (all have a “central pallor” which indicates the biconcave shape). Morphological abnormalities are rarely specific to a single condition but do give clues about the functional problem causing the abnormality.

Abnormalities of Erythrocytes

Written below are the most common abnormalities and their significance.

There is a lot of information here. The functional significance is useful to learn but given the non-specific nature of the abnormalities, the listed pathologies are better used as a reference.

Abnormalities in size

1. Macrocytosis/High MCV (Large RBC)

Type 1:

Image 01 2
Macrocytic RBCs (source)

Functional Significance:
RBCs decrease in size as they mature, so the presence of abnormally large RBCs indicates either disordered erythropoiesis or immature release from the bone marrow.

Associated Pathologies:
Macrocytic anaemias:
• Consequence of Haemolysis
• Pregnancy
Hypothyroidism
• Chronic Respiratory/Liver Failure
• Aplastic/Pernicious anaemia

Type 2:

Image 03
Oval Macrocytosis (source)

Functional Significance:
Oval macrocytosis

Associated Pathologies:
• Megaloblastic Anaemia (Folate/B12 Deficiency)
• Myelodysplasia

Type 3:

Image 03
Round Macrocytosis (source)

Functional Significance:
Round macrocytosis

Associated Pathologies:
Liver disease/alcoholism

2. Microcytosis/Low MCV (Small RBC)

Image 04 1 edited
Microcytic RBCs (source)
Functional Significance:
The presence of abnormally small RBCs, often seen in association with hypochromia.

Associated Pathologies:
• Macrocytic anaemias:
• Fe-deficiency anaemia
• Thalassaemia
• Anaemia of Chronic-Disease
• Congenital Sideroblastic Anaemia
• Rheumatoid Arthritis
• Sickle Cell Anaemia

3. Anisocytosis

Image 05
Anisocytosis (source)
Functional Significance:
Variation in RBC size. The more anisocytosis there is the bigger the RDW will be.

Associated Pathologies:
• Thalassaemia
• Fe-deficiency
• Megaloblastic Anaemia
• Haemolytic Anaemia
Sepsis

4. Dimorphic picture

Image 06
Dimorphic picture (source)
Functional Significance:
Describes heterogeneity in the size of RBCs, usually two distinctive size populations.

Associated Pathologies:
• Partially treated anaemia
• Mixed deficiency anaemia (e.g. Folate/B12 AND Fe-deficiency together)
• Following transfusion
• Sideroblastic Anaemia

Abnormalities in number
Increased space between RBCs
Functional Significance:
Indicates lower volume of RBCS
Associated Pathologies:
Various Anaemias

Abnormalities in colour
The colour of RBCs is reflected by its haemoglobin content
1. Hyperchromia

Image 07 1 e1608570240317
Hyperchromia (source)

Functional Significance:
Increased haemoglobinisation and the lack of a central pallor.
Associated Pathologies:
• Spherocytes
• Irreversible sickle cells
• Irregularly contracted cells (ICC or pyknocytes)

2, Hypochromia

Image 08
Hypochromia (source)

Functional Significance:
Impaired staining of RBCs due to reduced Hb in RBC.

Associated Pathologies:
• Fe-Deficiency Anaemia
• Thalassaemias
• Sideroblastic Anaemia
• Chronic inflammation
• Lead poisoning

3. Polychromasia

Image 09
Polychromasia (source)
Functional Significance:
Heterogeneous staining of RBCs due to RNA retention in larger immature cells, indicates bone marrow stress or haemolysis.

Associated Pathologies:
• Post haemorrhage
• Haemolysis
• Dyserythropoiesis
• Treated deficiency anaemias

Abnormalities in shape
Abnormally shaped red blood cells (poikilocytosis) isn't specific to any specific pathology.
1. Reticulocytes/Reticulocytosis

Image 10
Reticulocytes (source)

Functional Significance:
Reticulocytes are immature, oversized RBCs released from the bone marrow to circulate for around 1 day before maturing into erythrocytes. They should only comprise of about 1-2% of total RBCs and are a good indicator of bone marrow activity.

Type 1: Increased reticulocyte count
This indicates a high bone marrow activity

Associated Pathologies:
• Haemolytic anaemia
• Post-haemorrhage
• Severe hypoxia
• Polycythaemia, marrow infiltration
• Following marrow recovery post-chemotherapy
• Treatment of deficiency anaemias

Type 2: Decreased reticulocyte count
This indicates a reduced bone marrow activity or infiltration

Associated Pathologies:
• Aplastic/pernicious anaemia
• Anaemia of deficiency /chronic disease
• Chemotherapy
• Leukaemia/ myeloma/ lymphoma/ other malignancies
• Malnutrition
• Uraemia
• Drugs

2. Nucleated RBCs (Erythroblasts/Normoblasts)

Image 11 e1608151014285
Nucleated RBCs (source)

Functional Significance:
Nucleated RBCs are a precursor of reticulocytes and still have a nucleus. They should not normally be seen in an adult blood film and are pathological (leucoerythroblastosis). The circulating erythroblasts can be normoblasts (normal maturation), or megaloblasts (megaloblastic changes)

They are released into the bloodstream when:

a) There is a high demand for the bone marrow to produce RBCs so normal precursor cells are released prematurely

Associated Pathologies:
• Severe Anaemia (Haemolytic/Myelophthisic/Haemorrhagic)
• Thalassemia
• Hypoxia
• Sepsis

b) Erythropoiesis is taking place in the spleen

Associated Pathologies:
• Myelofibrosis

c) There is bone marrow infiltration by cancer cells

Associated Pathologies:
• Leukaemia
• Lymphoma
• Myeloma
• Secondary metastasis

3. Spherocytes

Image 12 1
Spherocytes (source)

Functional Significance:
• Rounded RBCs that have lost their biconcave shape due to membrane loss (usually in the spleen) and become spheres.
• This usually indicates active haemolysis.
• As a result of the shape, they cannot bend through capillaries as easily.

Associated Pathologies:
• DIC
• Autoimmune Haemolytic Anaemia
• Post-transfusion reaction
• Hereditary Spherocytosis
• G6PD deficiency
• Severe burns

4. Elliptocytes/Ovalcytes

Image 13 1
Elliptocytes (source)

Functional Significance:
• Similar to spherocytes but elliptical.
• Can cause fewer haemolysis symptoms than spherocytes due to less abnormal shape

Associated Pathologies:
• Hereditary Elliptosis/Spherocytosis
• Myeloproliferative disorder
• Myelodysplastic syndrome

5. Pencil/Rod/Cigar cell
Image 14
Cigar cells (source)

Functional Significance:
• Type of elliptocyte

Associated Pathologies:
• Occurs in Fe-deficiency anaemia
• Thalassaemia trait and syndromes
•Pyruvate kinase disease

5. Stomatocyte (mouth/slit cell)

Image 15 e1608151305627
RBC morphology including stomatocytes (source)

Functional Significance:
• Oval/rectangular area of central pallor due to a loss of concavity on one side

Associated Pathologies:
• Liver disease
• Alcoholism
• Electrolyte imbalance
• Hereditary Stomatocytosis
• Rh-null disease
• Obstructive lung disease
• Haemolytic Anaemia
• Volume overload

6. Codocytes (Target Cells/Mexican hat cells)

Image 16 e1608151125857
Codocytes (source)
Functional Significance:
• Central area of increased staining surrounded by a ring of hypodense straining and a further ring of dense staining at the edge of the cell.
• Occurs due to an increase in the surface membrane to volume ratio, either by increased membrane surface area or decreased intracellular haemoglobin.
• Not specific

Associated Pathologies:
• Thalassaemia
• Severe Fe-Deficiency Anaemia
• Liver disease (cholestasis)
• Sickle cell disease
• Haemoglobinopathies (abnormal inherited forms of haemoglobin – eg. Haemoglobin C trait / CC disease)
• Asplenia

7. Leptocytes

Image 21 e1608152432234
Leptocytes (source)

Functional Significance:
• Like codocytes but with thin borders that are also severely hypochromic

Associated Pathologies:
• Liver disease

8. Schistocytes (Helmet cells)

Image 15 e1608151305627
RBC morphology including schistocytes (source)

Functional Significance:
• Fragmented RBCs – caused by intravascular strands of fibrin or spleen dysfunction as the spleen removes RBCs from circulation.
• Small amounts can be seen in a normal individual.

Associated Pathologies:
• Intravenous haemolysis
• Renal failure
• Thrombotic micro-angiopathic Haemolytic Anaemias (TTP, DIC, HUS)
• Malignant hypertension
• Mechanical heart valve
• Atherosclerosis
• Severe burns
• Splenectomy

9. Dacryocytes (Teardrop cells)

Image 19 e1608151785389
Dacrocytes (source)
Functional Significance:
• Due to compression of RBCs during release either from a fibrosed bone marrow or extramedullary haemopoiesis (RBCs produced outside the bone marrow e.g. Spleen)

Associated Pathologies:
• Myelofibrosis and Myeloproliferative disorders (Leukaemia, Lymphoma, Myeloma)
• Metastatic marrow infiltration (Myelopthtisia)
• Myelodysplastic syndrome
• Severe Fe deficiency
• Hereditary Elliptocytosis/Pyropikilocytosis
• Megaloblastic Anaemia
• Thalassemia
• Organ failure

10. Drepanocytes (Sickle cells)

Image 15 e1608151305627
RBC morphology including drepanocytes (source)

Functional Significance:
• Crescent shaped RBCs due to misshapen haemoglobin causing rigid sickled RBCs

Associated Pathologies:
• Sickle cell anaemia/disease

11. Keratocytes (Blister cells)

Image 18 e1608151571204
Keratocytes (source)
Functional Significance:
• Cytoplasmic projections that fuse together creating a vacuole on the edge of the membrane, giving the appearance of a blister, created by inclusion bodies being removed by splenic macrophages, or by impalement of the RBC by fibrin strands, and the membrane reforming to produce the vacuole.

Associated Pathologies:
• Microangiopathic Haemolytic Anaemias
• Mechanical haemolysis
• Heinz body haemolytic anaemias (G6PD Deficiency, Thalassaemia)

12. Degmacytes (Bite cells)

Image 22
Degmacytes (source)

Functional Significance:
• Describes where the splenic macrophages have removed part of erythrocyte (e.g. to remove Heinz bodies – see below).
• If a blister cell ruptures it becomes a bite cell.

Associated Pathologies:
• G6PD deficiency
• Thalassaemia
• Oxidative stress
• Congenital Heinz body anaemia

13. Acanthocytes (spur, thorn cells)

Image 23 e1608153161257
Acanthocytes (source)
Functional Significance:
• Spiculated (spikey / irregularly edged cells) RBCs with 3-20 irregular spicules.
• They are microcytes and lack central pallor unlike echinocytes.
• The cell membrane damage is due to a decrease in membrane cholesterol

Associated Pathologies:
• Asplenia
• Alpha/beta-lipoproteinaemia
• Chronic liver disease
• Renal disease
• Hypothyroidism
• Alpha-Thalassaemia
• Hereditary Acanthocytosis
• Pyruvate Kinase deficiency
• Thrombotic micro-angiopathic haemolytic anaemias (TTP, DIC, HUS)
• Can also be artefact

14. Echinocytes

Image 24 e1608153319848
Echinocytes(source)
Functional Significance:
• Describes cells with many (10-30) regular spicules.

a) Burr Cells: type of Echinocyte, found in patients with uraemia

Associated Pathologies:
• Any cause of Uraemia
• Malnutrition
• Renal failure
Hypokalaemia
• Liver disease
• Pyruvate Kinase deficiency

b) Crenated cells: type of Echinocyte, normally due to storage or EDTA artefact

Associated Pathologies:
• Artefact (prolonged storage/slow drying)

Abnormalities in arrangement

1. Rouleaux

Image 15 e1608151305627
RBC morphology including Roleaux cells (source)

Functional Significance:
• Stacks/clumps of RBCs which develops when plasma acute-phase protein concentration is high.
• Often an indicator of a high ESR.

Associated Pathologies:
• Infections/Autoimmune conditions
• Chronic inflammation
• Paraproteinaemia
• Multiple Myeloma
• Waldenstroms macroglobulinaemia
• Diabetes Mellitus

2. Agglutination

Image 15 e1608151305627
RBC morphology including agglutination (source)
Functional Significance:
• Indicative of bound RBC antibodies.
• Distinguished from Rouleaux by diluting the blood with saline, rouleaux is dispersed but agglutination is not.
• Can falsely increase the MCV

Associated Pathologies:
• Cold haemagglutinin disease
• Waldenstroms macroglobulinaemia

Inclusion bodies
Inclusion bodies are seen within the RBCs; often due to defective maturation, oxidant injury or infection

1. Basophilic stippling (punctuate basophilia)

Image 15 e1608151305627
RBC morphology including agglutination (source)

Functional Significance:
• Describes the presence of small granular bodies (denatured RNA fragments) within the RBC cytoplasm due to disordered/accelerated erythropoiesis meaning RBCs with immature cytoplasm are released from the bone marrow.

Associated Pathologies:
• Haemaglobinopathies (Thalassaemias)
• Lead/Arsenic poisoning
• Megaloblastic/Haemolytic/Sideroblastic Anaemia
• Severe infections
• Pyrimidine 5’ Nucleotidase deficiency
• Nutritional deficiencies
• Myelofibrosis

2. Heinz Bodies

Image 28
Heinz bodies (source)

Functional Significance:
• Denatured Haemoglobin due to oxidative damage/unstable Hb.
• Normally removed by the spleen (becoming a bite/blister cell).
• Appears as “nose” or pale circle with specific staining.

Associated Pathologies:
• G6PD Deficiency
• Alpha-Thalassemia
• Autoimmune Haemolytic Anaemia
• Splenectomy/Asplenia
• Use of antioxidant drugs/sulphonamides
• Oxidative stress
• Congenital Heinz body anaemia

3. Howell-Jolly bodies

Image 15 e1608151305627
RBC morphology including Howell-Jolly bodies (source)
Functional Significance:
• Nuclear remnant found in RBCs, normally excluded before becoming reticulocytes and removed by the spleen

Associated Pathologies:
• Post-splenectomy
• Anatomical/Functional Asplenia
• Hereditary Spherocytosis
• Sickle Cell Anaemia
• Megaloblastic/Fe-deficiency anaemia
• (Rarely in Leukaemia)

4. Cabot’s rings

Image 15 e1608151305627
RBC morphology including Cabot rings (source)
Functional Significance:
• Red staining, circular/figure-of-eight structures thought to represent nuclear membrane remnants.

Associated Pathologies:
• Found in conditions similar to Howell-Jolly bodies

5. Siderocyte/Siderotic granules (Pappenheimer bodies)

Image 15 e1608151305627
RBC morphology including Pappenheimer bodies (source)
Functional Significance:
• Phagosomes containing ferruginous granules found in RBCs.
• May contribute to spurious platelet counts by electro-optical counters

Associated Pathologies:
• Iron-overloading disorders (Hereditary Haemochromatosis)
• Sideroblastic anaemia
• Haemolytic anaemia
• Sickle Cell Disease
• Carcinomatosis
• Post-splenectomy

6. Haemoglobin H inclusions

Haemoglobin H
Haemoglobin H inclusions (source)
Functional Significance:
• Characteristic ‘golf ball’ appearance of RBC with Brilliant Cresyl Blue staining which show the haemoglobin H bodies (beta globin chains from impaired formation of alpha-chains)

Associated Pathologies:
• Alpha-thalassaemia
• Haemoglobin H disease

7. Intracellular parasites

Functional Significance:
• Parasites seen within the cytoplasm
Associated Pathologies:
• Plasmodium
• Babesia
• Malarial parasites

The haematologist will sometimes give an opinion about differential diagnoses based on the film appearance and the clinical information provided, but it is useful for you to be able to recognise the abnormalities and patterns yourself. For example:

“Hyposplenic film” is a description of the collection of abnormalities found in these patients. They include Howell-Jolly bodies, target cells, occasional nucleated RBCs, lymphocytosis, macrocytosis and acanthocytes. There may also be evidence of infectious mononucleosis, any viral infection, toxoplasmosis and drug reactions.

Leucocytes

  • As with Erythrocytes, the number and morphology of each type of leucocyte is assessed in the peripheral smear.
  • Leucocytosis is an increase in the number of WBCs and leukopenia is a decrease in the number of WBCs.
  • Neutrophils are the most abundant type of leukocytes (40-70%), followed by lymphocytes (20-45%), eosinophils (1-6%), monocytes (2-10%) and basophils (<1%).
  • Increases or reductions in any WBC type may be either relative (normal white cell count) or absolute (abnormal white cell count)
Abnormalities of Leukocytes
Abnormalities in neutrophils

Also known as segmented neutrophils or polymorpho-nuclear cells (PMNs)

1. Neutropenia

Functional Significance:
• Decreased number of neutrophils

Associated Pathologies:
• Antineoplastic agents
• Extensive radiation therapy
• Drugs (allopurinol, phenothiazides)
• Viral infections
• Cyclic neutropenia
• Idiopathic neutropenia
• Hypersplenism
• Felty’s syndrome

2. Neutrophilia

Functional Significance:
• Increased number of neutrophils

Associated Pathologies:
• Response to bacterial infection
• Can also indicate any form of acute inflammation
• Burns
• Corticosteroid use (inhibits neutrophil adhesion to blood vessel walls known as "margination")
• Malignancy/myeloproliferative disorders

3. Left shift (Bands/Hyposegmented neutrophils)

Functional Significance:
• The abnormal rise in proportion of circulating neutrophil precursors

Neutrophil precursors from most to least mature: Band forms (stab, juvenile), Metamyelocyte, Myelocyte, Myeloblast (Granulocytes). Band neutrophils make up less than 8% of normal circulating neutrophils

Associated Pathologies:
• Myelodysplastic Syndrome
• Myelofibrosis
• Chemotherapy
• Acute infection

4. Leuko-erythroblastic anaemia

Functional Significance:
• Describes the presence of very immature blasts cells.

Associated Pathologies:
• Seen in cases of marrow infiltration (metastatic malignancy/leukaemic infiltration)
• Also prolonged hypoxia or severe infection

5. Leukemoid reaction

Functional Significance:
• The term for severe neutrophilia with left shift

Associated Pathologies:
• Severe infection
• Burns
• Acute haemolysis
• Prolonged hypoxia

6. Hypersegmentation

Functional Significance:
• Hyperlobulated nuclear segments

Associated Pathologies:
• Usually indicative of liver disease
• Uraemia
• Megaloblastic Anaemia

7. Toxic granulation

Functional Significance:
• Compensatory increase in microbicidal granules in the cytoplasm

Associated Pathologies:
Seen in:
• Severe infection
• Inflammatory disorders
• Chemical poisoning
• Alcohol abuse
• post op patients

8. Vacuolisation

Functional Significance:
• Vacuoles appear as holes in the cytoplasm

Associated Pathologies:
• Frequently found in association with toxic granulation

9. Döhle bodies

Functional Significance:
• Nuclear remnant inclusions in the peripheral cytoplasm

Associated Pathologies:
Frequently found in association with:
• Toxic granulation
• Vacuoles

Also found:
• Burns
• Trauma
• Acute/Systemic infections
• Cytotoxic agents (chemotherapy)
• Normal pregnancy

10. Auer rods

Functional Significance:
• Rod-shaped inclusions seen in very immature myeloblasts

Associated Pathologies:
• Pathognomonic for Acute Myeloid Leukaemia (AML)

11. Pelger-Huët

Functional Significance:
• Describes bilobed neutrophils, shaped like a peanut or dumbbell

Associated Pathologies:
Hereditary: Pelger-Huët
Acquired: Myelodysplastic syndromes (pseudo- Pelger-Huët/Pelgeroid cells)

12. Alder-Reilly Granules

Functional Significance:
• Large, dark leucocyte granules that stain purple

Associated Pathologies:
• Indicative of mucopolysaccharidosis (inherited enzyme deficiency disorder, e.g. Hurler’s and Hunter’s syndromes)

13. Chédiak-Higashi granules

Functional Significance:
• Presence of variable sized granules that can be found in neutrophil blasts, lymphocytes and monocytes
• Indicates a lethal metabolic disorder

Associated Pathologies:
• Chédiak-Higashi syndrome

Abnormalities in lymphocytes

1. Lymphocytopenia

Functional Significance:
• Decreased number of lymphocytes

Associated Pathologies:
• Can commonly occur with viral infections
• Corticosteroid use
• Various acute illnesses
• HIV/AIDS
• Seen in association with several congenital diseases of the immune system
• Antineoplastic or radiation use

2. Lymphocytosis

Functional Significance:
• Increased number of lymphocytes

a) Absolute lymphocytosis: total lymphocyte count is increased

Associated Pathologies:
• Acute viral infections (e.g. Infectious mononucleosis/EBV)
• Chronic intracellular bacterial infections (TB/brucellosis)
• Chronic lymphocytic leukaemia
• Acute lymphoblastic leukaemia

b) Relative Lymphocytosis: higher proportion of lymphocytes making up WBCs but the total count is normal

Associated Pathologies:
• Can accompany viral infections
• Addison’s disease
• Autoimmune disorders
• Lymphoproliferative disorders

c) Reactive lymphocytosis (Atypical, Activated, Downey cells): large lymphocytes that contain a greater amount of cytoplasm and vary in size/shape

Associated Pathologies:
• Acute viral infections (e.g. Infectious mononucleosis/EBV)

Also in:
• Connective tissue diseases
• Thyrotoxicosis
• Adrenal insufficiency

3. Neoplastic lymphoid blasts

Functional Significance:
• Increased number of lymphocytes

a) Lymphoma cells (follicular/mantle cells)

Associated Pathologies:
• Leukaemic phase of Non-Hodgkin’s Lymphoma

b) Villous lymphocytes

Associated Pathologies:
• Splenic marginal zone lymphoma

c) Hairy cells

Associated Pathologies:
• Hairy cell leukaemia

d) Smear cells (cell membranes rupture in film preparation)

Associated Pathologies:
• Chronic Lymphocytic Leukaemia

Abnormalities in eosinophils

1. Eosinopenia

Functional Significance:
• Decreased number of eosinophils

Associated Pathologies:
• Pregnancy
• Acute stress/inflammation

2. Eosinophilia

a) Increased number of eosinophils

Associated Pathologies:
• Hypersensitivity states (allergic responses, inflammatory states)
• Parasite infections

b) Marked eosinophilia (>1500/ml)

Associated Pathologies:
• Suggests hypereosinophilic syndrome, or a neoplastic entity e.g. Chronic eosinophilic leukaemia

Abnormalities in basophils

1. Basopenia

Functional Significance:
• Decreased number of basophils

Associated Pathologies:
• Acute stress
• Ovulation
• Steroid use

2. Basophilia

Functional Significance:
• Increased number of basophils

Associated Pathologies:
Seen in:
• Hypersensitivity states (allergic response, Ulcerative Colitis, Chronic Sinusitis, chicken pox, immunisations)
• Lymphomas and Chronic Myeloid Leukaemia

Abnormalities in monocytes

1. Monocytopenia

Functional Significance:
• Decreased number of monocytes

Associated Pathologies:
• Chemotherapy
• Aplastic Anaemia
• Severe burns
• AIDS

2. Monocytosis

Functional Significance:
• Increased number of monocytes

Associated Pathologies:
• Chronic bacterial infections (TB/brucellosis)
• Inflammatory conditions (Crohn’s disease)
• Rheumatic diseases (Lupus/RA)
• Haematological malignancies (e.g. Acute/Chronic Myeloid Leukaemias, Lymphomas)

Thrombocytes (Platelets)

Thrombocytopaenia (decrease in number) can result from:

  • Reduced production (bone marrow failure syndromes)
  • Increased peripheral destruction (thrombotic micro-angiopathies)
  • Increased splenic sequestration (hypersplenism)

Thrombocytosis (increase in number) can result from:

  • Infections
  • Major surgeries
  • Post-splenectomy
  • Haemorrhage
  • Acute haemolysis
  • Fe-deficiency
  • Connective tissue disorders
  • Use of cytokines, and certain drugs
  • Malignant conditions especially myeloproliferative neoplasms (polycythaemia vera, myelofibrosis, essential thrombocythaemia)

Megathrombocytes (increased size) are caused by hyperactivity of megakaryocytes due to increased demand commonly due to B12/folate deficiency or myeloproliferative disorders, or more rarely due to congenital thrombocytopaenic conditions (Bernard-Soulier syndrome, May-Haggelin anomaly (along with Dohle-doy inclusions) or Wiskott-Aldrich syndrome).

Platelet hypogranularity is seen in myelodysplastic syndrome and myelofibrosis, along with megakaryocytes.

Other abnormalities

  • Parasite, fungal, or circulating carcinoma cells might be seen

Useful Resources & References

Written by Dr Kristen Sellick (FY3)
Reviewed by Dr Ailsa Gemmell (IMT1)
Edited by Mr Mudassar Khan (Y3 Medical Student)

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Preparing for the Situational Judgement Test (SJT) exam can be quite daunting. It makes up 50% of your...

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