RBC Morphology Flashcards
What is the normal morphology of red blood cells?
- 7.5 micrometres (roughly the size of a lymphocyte nucleus).
- Central pallor (central pale area) takes up approximately 1/3rd of the cell.
What is anisoscytosis?
Red blood cells that are of different sizes. Normal red blood cells are generally the same size.
Having red blood cells of unequal sizes may be a sign of anemia
What is poikilocytosis?
An increase in abnormal red blood cells of any shape that makes up 10% or more of the total population
What is microcytosis?
Red blood cells smaller than 7-7.2 micrometres.
Indicates microcytic anaemia.
What are the causes of microcytic anaemia (TAILS)?
Thalassaemia
Anaemia of chronic disease
Iron deficiency
Lead poisoning
Sideroblastic anaemia
How is microcytosis identified on a blood film?
Comparing the RBC diameter to the nucleus of the lymphocyte. If the RBC is smaller, this indicated microcytosis.
What is macrocytosis?
Red blood cells larger than 7-7.2 micrometres.
Indicates macrocytic anaemia.
What are the causes of non-megaloblastic macrocytic anaemia (HAND LAMP)?
Hypothyroidism
Aplastic anaemia
Neonate
Drugs e.g. azathropine
Liver disease
Alcohol
Myelodysplasia
Pregnancy
What are elliptocytes?
Thin, elongated RBC’s
What are the causes of elliptocytes?
Iron deficiency
Myelodysplastic syndrome
Hereditary elliptocytosis
What are schistocytes?
RBC fragments. These are fragmented red cells resulting from sheer stress (mechanical damage).
What are the causes of schistocytes?
Microangiopathic haemolytic anaemia
Mechanical e.g. metallic cardiac valve haemolysis
What are spherocytes?
Cells that lack central pallor and are spherical in shape (lost their membrane without losing their cytosol).
What are the causes of spherocytes?
Hereditary spherocytosis
Warm and cold AIHA
Immediate and delayed haemolytic transfusion reaction
ABO haemolytic disease of the newborn
Drug-induced haemolytic anaemia i.e. ceftriaxone.
Burns
Cold agglutination disease
What are stomatocytes?
RBC’s with a slit like area of central pallor. Occurs as a result of a decreased surface area to volume ratio in RBC’s.
Causes of stomatocytes?
Hereditary stomatocytosis
Liver disease
What are “target” cells?
RBC’s that have areas of increase staining due to redundant RBC membrane in relation to the cytoplasm.
Causes of “target” cells (Mnemonic: LOTSS)?
Liver disease
Obstructive jaundice
Thalassaemia
Splenectomy
Sideroblastic anaemia
Characteristic feature of “target” RBC’s?
Contains a characteristic “bullseye” appearance
What are “tear drop” cells?
RBC’s that are round at one side and tapered at the other.
Arises from conditions that affect the bone marrow architecture and resulting in RBC’s exiting the bone marrow
Causes of “tear drop” cells?
Bone marrow fibrosis
Bone marrow infiltration
What are Howell-Jolly bodies?
Normal RBC nuclear DNA remnants which are normally removed by the spleen.
Causes of Howell-Jolly bodies?
Splenectomy
Hyposplenism (impaired spleen function)
Neonates with functionally immature spleens
How does a Howell-Jolly body appear on blood film?
Dark purple spot within the RBC.
What are Pappenheimer bodies?
Small aggregates of ferritin.
Such debris is normally removed by the spleen.
Causes of Pappenheimer bodies?
Post-splenectomy
Lead poisoning
Sideroblastic anaemia
How do Pappenheimer bodies appear on blood film?
Usually presents as smaller faint dots inside the RBC’s.
What are the indications for splenectomy?
ITP
AIHA
Thalassaemia intermedia (old indication)
Congenital RBC membrane defects
- Hereditary spherocytosis
- Hereditary elliptocytosis
Lymphoproliferative disorders
- Splenic marginal zone lymphoma
- Hairy cell leukaemia (old indication)
Myelofibrosis (old indication)
Trauma
