Hematology - RBC Morphology, Inclusions, & Stains Flashcards
What diseases are macrocytes associated with?
- megaloblastic anemias (B12/folate deficiency)
- liver disease
- accelerated erythropoiesis (reticulocytosis)
-normal in newborns
What diseases are associated with microcytes?
- iron deficiency anemia
- thalassemias
- sideroblastic anemia
- anemia of chronic disease
What is anisocytosis?
variation in RBC size - indicating a dimorphic population
What RBC parameter does anisocytosis correlate with?
RDW - esp. when it exceeds 15%
What diseases are associated with anisocytosis?
- post-transfusion
- post-treatment (B12, iron, folate)
- presence of 2 concurrent deficiencies (e.g., iron and B12)
- idiopathic sideroblastic anemia
What is poikilocytosis?
variation in the shape of RBCs
Echinocyte (Burr cell)
What is the clinical significance of echinocytes (burr cells)?
-membrane defect
- liver disease
- uremia
- hemolytic anemias
- TTP
- DIC
- carcinoma of stomach
- pyruvate kinase deficiency
What is the clinical significance of crenated RBCs?
-osmotic imbalance
-if seen in most cells in thin part of smear, do not report = probably artifact due to excess anticoagulant or slow drying
How can crenated RBCs be differentiated from burr cells?
Burr cells have more pointed projections as compared to the knobby projections of crenated cells.
-if the abnormality is seen in nearly all cells in the thin part of the smear, it is most likely artifact (crenation) due to slow drying of the smear or over-anticoagulation
-burr cells are seen in variable number throughout the smear
What is hypochromia?
the are of central pallor is greater than 1/3 the diameter of the RBC
spur cells (acanthocytes)
What is the clinical significance of acanthocytes (spur cells)?
-membrane defect (excessive cholesterol)
- alcoholic liver disease
- post-splenectomy
- abetalipoproteinemia
How are echinocytes and acanthocytes differentiated on a smear?
target cells (codocytes)
What causes target cells (codocytes)?
-excessive cholesterol in membrane
-hemoglobin distribution imbalance
What is the clinical significance of target cells (codocytes)?
- liver disease
- hemoglobinopathies (sickle cell, hemoglobin C)
- thalassemia
- iron-deficiency anemia
teardrops (dacrocytes)
What is the clinical significance of dacrocytes (tear drop)?
- anemias (megaloblastic)
- thalassemia
- extramedullary hematopoiesis (myelofibrosis)
sickle cells (drepanocytes)
schistocyte (RBC fragments)
What is the clinical significance of schistocytes?
-RBCs split by fibrin strands
- microangiopathic hemolytic anemias (DIC, TTP, HUS)
- prosthetic heart valves
- burns
What are spherocytes?
small, dark-staining RBCs without central pallor
spherocyte
What is the clinical significance of spherocytes?
membrane defect
-hereditary spherocytosis
-autoantibodies
-burns
-hemoglobinopathies
-hemolysis
-ABO HDFN
-incompatible blood transfusion
-transfusion of stored blood
-a few are normal due to aging of RBCs
How are the MCV and MCHC affected in hereditary spherocytosis?
MCV: normal to low
MCHC: slightly increased
On a blood smear spherocytes appear small in comparison to normal RBCs. Explain how their MCV may be normal.
Although spherocytes are small in diameter, their volume is normal because they are spherical rather than biconcave.
What are stomatocytes?
RBCs with a slit-like central pallor
(mouth cells)
What is the clinical significance of stomatocytes?
-hereditary stomatocytosis
-hereditary spherocytosis
-thalassemia
-alcoholic cirrhosis
-Rh null disease
-may be artifact in parts of the smear that are too thin or too thick
stomatocyte
What is the clinical significance of marked polychromasia?
it is a sign of accelerated erythropoiesis
-acute blood loss
-hemolytic anemia
-following anemia treatment
-supravital stain = retics
polychromasia
Describe rouleaux.
RBCs resemble a stack of coins
What is the clinical significance of rouleaux?
serum protein abnormality - increased globulin or fibrinogen
-multiple myeloma
-macroglobulinemia
-may be artifact = delay in spreading drop of blood OR smear is too thick
What is the clinical significance of agglutination on a blood smear?
RBCs in irregular clumps - RBCs coated with IgM antibodies and complement
-autoantibodies
-cold autoagglutination
Rouleaux vs. agglutination
Why is it important to report oval macrocytes?
because of their association with megaloblastic anemia
What is the clinical significance of hypochromic microcytic RBCs?
-iron deficiency anemia
-sideroblastic anemia
-thalassemia
-anemia of chronic inflammation
In what ways will the RBC morphology of a newborn differ from that of an adult?
-macrocytic and polychromatophilic
-a few nucleated RBCs (3-10 per 100 WBCs)
-Reference ranges are higher for newborns: WBCs, RBCs, hematocrit, hemoglobin, retics
What effect does chronic alcoholism have on RBC morphology?
-MCV is elevated
-target cells
-stomatocytes