Hemato-pathology guide

Question 1

Red cell distribution width (RDW)

Answer 1

Standard deviation of the MCV
• Tells you how much the red blood cells differ from each other in size. If they are all pretty
similar in size, the RDW is low. If some are little and some are big, the RDW is high.
• Normal range = 12-13.5%
• Used to differentiate between anemias with minimal anisocytosis (difference in cell size)
(RDW 12-13.5%) and those with increased anisocytosis (RDW > 13.5%).
• You can see this on a blood smear: when anisocytosis is increased, you’ll see a range of
cell sizes – some are smaller, some are bigger.

Question 2

Platelet count (Plt)

Answer 2

• Total number of platelets in blood
• Normal range = 150-450 x 109/L
• Causes of a low platelet count are numerous and include splenomegaly, idiopathic
thrombocytopenic purpura, disseminated intravascular coagulation, and bone marrow failure. Causes of a high platelet count are also numerous, and include reactive thrombocytosis (as seen in iron-deficiency anemia) and essential thrombocythemia.

Question 3

anisocytosis

Answer 3

• Oval macrocytes (B12/folate deficiency)
• Microcytes (iron deficiency anemia, thalassemia)
• The size range can often help you narrow down which type of anemia is present
(for example, in iron-deficiency anemia, there is usually a big range of sizes)

Question 4

poikilocytosis

Answer 4

• Schistocytes (microangiopathic hemolytic anemia)
• Spherocytes (hemolytic anemia, hereditary spherocytosis)
• Teardrop cells or dacryocytes (myelofibrosis or myelophthisic processes)
• Target cells or codocytes (hemoglobinopathies, thalassemias, liver disease)
• Sickle cells (sickle cell anemia)
• Echinocytes and acanthocytes (liver disease)

Question 5

t(9;22)

Answer 5

CML

Question 6

trisomy 12

Answer 6

CLL

Question 7

t(8.21)

Answer 7

AML-M2

Question 8

t(15;17)

Answer 8

AML-M3

Question 9

inv(16)

Answer 9

AML-M4

Question 10

11q23

Answer 10

AML-M4 and M5

Question 11

t(11;14)

Answer 11

T-cell ALL

Question 12

t(9;22)

Answer 12

B-cell precursor ALL

Question 13

t(8;14)

Answer 13

B-cell ALL

Question 14

Make too little blood

Answer 14

• Bad diet (not enough iron, B12, or folate)
• Decreased number of erythroblasts (as in aplastic anemia)
• Bone marrow full of other stuff besides hematopoietic precursors (e.g., tumor)
• Chronic disease (e.g., renal disease, inflammatory diseases)

Question 15

Anemias with abnormally-sized red cells

Answer 15

• Red cells too small (microcytic) (iron-deficiency anemia, thalassemia)
• Red cells too big (macrocytic) (megaloblastic anemia)

Question 16

Anemias with abnormally-shaped red cells

Answer 16

• Round red cells (spherocytes) (hereditary spherocytosis, autoimmune hemolytic anemia)
• Pointy red cells (sickle cell anemia, G6PD deficiency, microangiopathic hemolytic anemia)
• Target-shaped red cells (hemoglobinopathies, thalassemias)

Question 17

Anemias with normal-looking red cells

Answer 17

• Increased reticulocytes (massive hemorrhage that occurred over 3 days ago)
• No increase in reticulocytes (recent massive hemorrhage, anemia of chronic disease,
aplastic anemia)

Question 18

folate deficiency

Answer 18

Blood
• Macrocytic anemia (MCV >100)
• Oval macrocytes.
• Hypersegmented neutrophils.
Bone marrow
• Megaloblastic erythroblasts (BIG cells with big,
immature nucleus but maturing cytoplasm).
• Megaloblastic neutrophils and precursors.
• Giant metamyelocytes.
• Hypersegmented neutrophils.

Question 19

Target cells

Answer 19

(thalassemias and hemoglobinopathies)

Question 20

Schistocytes

Answer 20

microangiopathic hemolytic anemia

Question 21

Signs of increased erythropoiesis

Answer 21

• Polychromatophilia (or, if stained with supravital stain, reticulocytosis)
• Basophilic stippling (RNA remnants not yet removed from cell)
• Nucleated red blood cells (bone marrow hurrying to get red cells out as quickly as possible)

Question 22

Direct antiglobulin test (DAT)

Answer 22

Also called the Coomb’s test. Mix patient’s red cells with anti-human globulin (an antibody against human immunoglobulins). If the patient’s red cells are coated with antibodies (as they are in some immune processes, see later), the anti-human globulin will attach to those antibodies, bridging the red cells and making them clump together. So, a positive result (red cell clumping) means the patient’s red cells are coated with antibodies, and the hemolysis is probably immune-related.