Haematology

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Blood Film Staining – Normal & Malignant Cells

Case Study 1

Male 72 yrs

Hb 77g/l (NR 130-180)
RBC 2.23 x 10¹²/l (NR 4.5-6.5)
MCV 88fl (NR 76-96)
WBC 98.2 x 10/l (NR 4-11)
Platelets 28 x 10/l (NR 150-400)

A) Calculation of PCV (packed cell volume or haematocrit)

PCV = RBC (cells/l) x 10¯¹² x MCV (fl)

RBC = 2.23 x 10¹²/l
MCV = 88fl or 88 x 10/l

PCV = 2.23 x 88 x10
PCV = 196.24/1000
PCV = 0.196 (NR 0.4-0.54)

B) Calculation of MCH (mean cell volume)

MCH = Hb (g/dl) x 10
RBS (cells/l) x 10¯¹²

Hb = 77g/l or 7.7g/dl
RBC = 2.23 x 10¹²/l

MCH = 7.7 x 10 =34.52 pg (10¯¹²g)/cell (NR 27-32 pg (10¯¹²g)/cell) 2.23

C) Calculation of MCHC (mean corpuscular haemoglobin concentration)

MCHC = Hb (g/dl)
PCV (l/l)

Hb = 77g/l or 7.7g/dl
PCV = 0.196

MCHC = 7.7 = 39.3g/dl or 393 g/l (NR 30-35 gt/dl)
0.196

The blood film shows large number of abnormal immature white cells (blasts), possibly hypergranular promyleocytes, which are rare in the blood of healthy person.

Promyleocytes are larger than myeloblasts with more plentiful cytoplasm and consequently a lower nucleocytoplasmic ratio. They cytoplasm is more basophilic than that on myeloblasts and contains azurophilic (pinkish-purple) primary granules. The nucleus is round or oval, is usually eccentric, shows some chromatin condensation and has visible nucleolus. Because they have no specific (lineage-associated) granules, promyleocytes, which are precursors of neutrophils, esinophils or basophils, cannot generally be distinguished from each other (Bain 2004).

Blood count results show low haemoglobin (Hb) concentration in the blood and the red cell count (RBC) is also low, there for packed cell volume (PCV) appears as well low. Mean cell volume (MCV) is within the normal reference range, which means that the red cells are normal size. White blood cell count (WBC) is highly increased and platelets count is decreased. Fall in platelets number can be due to increased number of cancer cells in bone marrow, a fall in platelets count prevent formulation of clots, which leads to haemorrhage resulting in internal or external bleeding. Mean corpuscular haemoglobin (MCH) is just a little bit over the normal recommended range and mean corpuscular haemoglobin concentration (MCHC) is increased. Increased MCHC values might mean that the haemoglobin inside the cells is abnormally concentrated.

In this case it is possible that the patient has acute myeloid leukaemia (AML). Sudan black and myeloperoxidase staining of blood are positive and that indicates the possibility of AML. AML is subdivided into different subtypes: M0-M7 .

The blood film shows possible acute promyleocytic leukaemia (M3 AML), which is characterised by abnormal hypergranular promyleocytes, acytogenic translocation, and a bleeding disorder secondary to consumptive coagulopathy and fibrynolysis (Bhagavan 2002)

To confirm the diagnosis the lumbar puncture for cerebrospinal fluid examination should be preformed (Hoffbrand 2006) and it may show that the spinal fluid contains leukaemic cells.

Cell surface markers should be identified, in this case it’s CD13+, CD33+, CD117- and CD15- (Hoffbrand 2006)

The bone marrow should be examined to see if it is hypercellular with leukaemic blasts.

Tests for disseminated intravascular coagulation (DIC) should be performed. And as for M3 AML it is often positive result.

Cytogenic and molecular analysis should be performed. The cytogenic hallmark for M3 AML consists of a balanced reciprocal translocation between the long arms of chromosomes 15 and 17, designated as t (15; 17). The translocation results in two recombinant chromosomes, one abnormally long 15q+ and one shortened 17q-. This translocation fuses the acute promyelocytic leukaemia gene located on chromosome 15 with the retinoic acid receptor (RARα) gene located on chromosome 17 (Bhagavan...
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