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Figure 12.10 Some of the common morphologic abnormalities of red cells (The serial numbers in the illustrations correspond to the order in CHAPTER 12
which they are described in the text).

Pappenheimer bodies which stain positively). Classical vii) Acanthocytosis is the presence of coarsely crenated red
punctate basophilia is seen in aplastic anaemia, thalassaemia, cells. Acanthocytes are found in large number in blood film
myelodysplasia, infections and lead poisoning. made from splenectomised subjects, and in chronic liver
iv) Howell-Jolly bodies are purple nuclear remnants, usually disease.
found singly, and are larger than basophilic stippling. They viii) Burr cells are cell fragments having one or more spines.
are present in megaloblastic anaemia and after splenectomy. They are particularly found in uraemia.
5. Miscellaneous changes. In addition to the morphologic ix) Stomatocytosis is the presence of stomatocytes which have
changes of red cells described above, several other abnormal central area having slit-like or mouth-like appearance. They
red cells may be found in different haematological disorders. are found in hereditary stomatocytosis, or may be seen in
Some of these are as follows (Fig. 12.10): chronic alcoholism.
i) Spherocytosis is characterised by presence of spheroidal x) Ovalocytosis or elliptocytosis is the oval or elliptical shape
rather than biconcave disc-shaped red cells. Spherocytes are of red cells. Their highest proportion (79%) is seen in
seen in hereditary spherocytosis, autoimmune haemolytic hereditary ovalocytosis and elliptocytosis; other conditions
anaemia and in ABO haemolytic disease of the newborn. showing such abnormal shapes of red cells are megaloblastic Introduction to Haematopoietic System and Disorders of Erythroid Series
ii) Schistocytosis is identified by fragmentation of erythro- anaemia and hypochromic anaemia.
cytes. Schistocytes are found in thalassaemia, hereditary C. RED CELL INDICES. An alternative method to diagnose
elliptocytosis, megaloblastic anaemia, iron deficiency and detect the severity of anaemia is by measuring the red
anaemia, microangiopathic haemolytic anaemia and in cell indices:
severe burns. In iron deficiency and thalassaemia, MCV, MCH and
iii) Irregularly contracted red cells are found in drug and MCHC are reduced.
chemical induced haemolytic anaemia and in unstable In anaemia due to acute blood loss and haemolytic
haemoglobinopathies. anaemias, MCV, MCH and MCHC are all within normal
iv) Leptocytosis is the presence of unusually thin red cells. limits.
Leptocytes are seen in severe iron deficiency and In megaloblastic anaemias, MCV is raised above the
thalassaemia. Target cell is a form of leptocyte in which there normal range.
is central round stained area and a peripheral rim of
haemoglobin. Target cells are found in iron deficiency, D. LEUCOCYTE AND PLATELET COUNT. Measurement
thalassaemia, chronic liver disease, and after splenectomy. of leucocyte and platelet count helps to distinguish pure
v) Sickle cells or drepanocytes are sickle-shaped red cells found anaemia from pancytopenia in which red cells, granulocytes
and platelets are all reduced. In anaemias due to haemolysis
in sickle cell disease. or haemorrhage, the neutrophil count and platelet counts
vi) Crenated red cells are the erythrocytes which develop are often elevated. In infections and leukaemias, the leucocyte
numerous projections from the surface. They are present in counts are high and immature leucocytes appear in the blood.
blood films due to alkaline pH, presence of traces of fatty
substances on the slides and in cases where the film is made E. RETICULOCYTE COUNT. Reticulocyte count (normal
from blood that has been allowed to stand overnight. 0.5-2.5%) is done in each case of anaemia to assess the marrow