Cell Morphology Flashcards
Erythrocytes of what species?
Normal Canine
Morphology: relatively large, uniform red blood cells with central pallor.
Lifespan: 110 – 120 days
Erythrocytes of what species
Normal Feline
“Morphology: relatively small red blood cells with some variability in size and shape and little to no central pallor.
Lifespan: 65 – 76 days
Erythrocytes of what species?
Normal Equine
Morphology: relatively small, uniform red blood cells with little to no central pallor.
Lifespan: 140 – 150 days
Other features: rouleaux may be prominent in healthy horses. Polychromatophils are not observed in blood of healthy horses and rarely observed with anemia (degree of regenerative response to anemia in horses cannot be assessed by quantifying reticulocytes). Foals (up to 1 year of age) may show microcytosis due to physiologic iron deficiency.”
Erythrocytes of what species?
Normal Bovine
Morphology: relatively small red blood cells with mild anisocytosis and a small amount of central pallor.
Lifespan: 160 days
Other features: basophilic stippling common with regenerative response. Young calves (< 3 months) may show marked poikilocytosis, thrombocytosis, and microcytosis (microcytosis may persist up to 1 year of age due to physiologic iron deficiency). Polychromatophils are rare in healthy cattle.”
Erythrocytes of what species?
Normal Camelid
Morphology: llamas, alpacas, and camels have small, flat, oval-shaped red blood cells.
Lifespan: 60 days
Other features: mild anisocytosis and poikilocytosis may be present in healthy llamas. Mean corpuscular hemoglobin concentration (MCHC) in camelids are significantly higher than other species (usually 40-50 g/dL).”
What is this abnormal morphology?
Acanthocytes
“Morphology: red blood cells with irregular spicules projecting from the cell surface. Spicules are variable in shape (blunt or bulbous tips), variable in size, and unevenly distributed around the periphery of the cell.
Look alike: echinocytes
Clinical relevance: may be associated with certain underlying disorders including hemangiosarcoma (dogs), liver disease (dogs and cats), disseminated intravascular coagulation (dogs), vasculitis (dogs), iron deficiency anemia (dogs). May also be observed in animals on high lipid diets. Small numbers may be normal in young ruminants (calves).”
What is this abnormal morphology?
Echinocytes
“Morphology: red blood cells with small, regular spicules projecting from the cell surface. Spicules are uniform in shape with sharp or blunt tips, uniform in length, and evenly spaced around the periphery of the cell.
Look alike: acanthocytes
Clinical relevance: usually an artifact with no pathological significance (stored blood, excess EDTA, increased blood pH). May occasionally be observed with certain drugs (furosemide in horses, doxorubicin in dogs and cats). May occasionally be observed with certain disorders (electrolyte depletion, glomerulonephritis, snake envenomation, burns, bee stings).”
What is this abnormal morphology?
Eccentrocytes
“Morphology: red blood cells with a clear crescent-shaped area along one side of the periphery. Formed by the fusion of two layers of oxidized cell membrane with no hemoglobin in between.
Commonly seen with: Heinz bodies
Clinical relevance: indicates oxidant injury to red blood cells. Oxidant injury may result from certain drugs (propofol and acetaminophen in cats) or from toxins (onions, red maple leaves in horses, zinc in dogs, copper in sheep, anticoagulant rodenticide in dogs, and skunk musk in dogs). Oxidant injury may also result from certain diseases (lymphoma and diabetes mellitus in dogs).”
What is this abnormal morphology?
Keratocytes
“Also called: blister cells (vesicle), helmet cells (ruptured)
Morphology: red blood cells with a blister-like vesicle on the margin, or a bite-shaped defect with horn-like projections on the margin (which results from rupture of vesicle).
Commonly seen with: schizocytes and acanthocytes (if caused by fragmentation injury), microcytosis and hypochromia (if caused by iron deficiency), eccentrocytes and Heinz bodies (if caused by oxidant injury)
Clinical relevance: indicates fragmentation injury to red blood cells related to vascular abnormalities (ie. disseminated intravascular coagulation, glomerular disease, vasculitis, hemangiosarcoma), mechanical fragility of red blood cells (ie. iron deficiency), or oxidant injury (ie. toxicity). May be associated with hepatic lipidosis in cats. Small numbers of keratocytes may be normal in healthy cats. “
What is this abnormal morphology?
Schizocytes
Also called: schistocytes
Morphology: red blood cell fragments. Usually oblong with irregular margins, but may appear in a variety of shapes and sizes.
Commonly seen with: keratocytes and acanthocytes (if caused by fragmentation injury), microcytosis and hypochromia (if caused by iron deficiency)
Clinical relevance: indicates fragmentation injury to red blood cells related to vascular abnormalities (ie. disseminated intravascular coagulation, glomerular disease, vasculitis, portosystemic shunts, hemangiosarcoma) or mechanical fragility of red blood cells (ie. iron deficiency). Small numbers of schizocytes may be normal in healthy dogs.”
What is this abnormal morphology?
Spherocytes
“Morphology: red blood cells with a spherical rather than biconcave shape. Spherocytes appear smaller than normal red blood cells, with loss of central pallor in dogs.
Look alike: microcytes (may be difficult to distinguish microcytes from spherocytes in cats, horses, and cattle due to lack of central pallor in normal red blood cells)
Commonly seen with: other features of immune-mediated hemolytic anemia (IMHA) including ghost cells, polychromatophils, and agglutination of red blood cells
Clinical relevance: large numbers of spherocytes are associated with IMHA. Spherocytes may also be observed in stored or transfused blood. Very small numbers of spherocytes in the feathered edge may not have any clinical significance. Presence of spherocytes does not usually affect mean cell volume (MCV) on CBC because cell volume is the same (cell has decreased diameter but increased roundness).”
What is this abnormal morphology?
Poikilocytosis
“Morphology: poikilocyte is a generic term to describe red blood cells with abnormal shape. Poikilocytosis refers to large numbers of abnormally shaped red blood cells.
Commonly seen with: poikilocytosis may include acanthocytes, echinocytes, eccentrocytes, keratocytes, and schizocytes as well as red blood cells with abnormal shape that do not fit available descriptors. Poikilocytosis may be accompanied by features of various underlying disorders.
Clinical relevance: depends on number, shape, and context. Marked poikilocytosis may be normal in young ruminants, some goat breeds, and pigs with artifactual crenation of erythrocytes. Pathological poikilocytosis is common in sick cats (ie. liver disease, cardiomyopathy, etc) and in animals receiving chemotherapy.”
What is this abnormal morphology?
Codocytes
Also called: target cells
Morphology: canine red blood cells with a bullseye appearance. Caused by increased ratio of cell membrane to hemoglobin content which results in a central bulge.
Look alike: torocytes
Clinical relevance: may be associated with regenerative anemia (polychromatophilic codocytes), iron deficiency anemia (hypochromic codocytes), liver disease and hypercholesterolemia (normochromic codocytes). Only observed in canine red blood cells with central pallor.”
What is this abnormal morphology?
Macrocytes
Morphology: red blood cells that are larger than normal, may be hypochromic or normochromic.
Look alike: polychromatophils (also larger than normal but stain dark purple).
Commonly seen with: other features of regenerative anemia (polychromatophils, anisocytosis, basophilic stippling).
Clinical relevance: commonly associated with regenerative anemia. In horses, macrocytosis may be the only observable feature of regenerative anemia. May be normal in Poodles. Macrocytosis usually corresponds to increased mean cell volume (MCV) on CBC.”
What is this abnormal morphology?
Microcytes
Morphology: red blood cells that are smaller than normal. May be hypochromic or normochromic. Central pallor is preserved (in dogs).
Look alike: spherocytes (may be difficult to distinguish spherocytes from microcytes in cats, horses, and cattle due to lack of central pallor in normal red blood cells).
Commonly seen with: other features of iron deficiency anemia (hypochromasia).
Clinical relevance: often associated with iron deficiency and portosystemic shunts. May be normal in young animals (puppies and kittens 4-8 weeks of age, calves and foals up to 1 year of age) due to physiologic iron deficiency. May also be normal in Japanese dog breeds (Akita, Shiba Inu). Microcytosis usually corresponds to decreased mean cell volume (MCV) on CBC.”
What is this abnormal morphology?
Anisocytosis
Morphology: variation in red blood cell size due to the presence of red cells larger than normal (macrocytes and polychromatophils), red cells smaller than normal (microcytes and spherocytes), or both.
Commonly seen with: features of regenerative anemia (macrocytosis and polychromatophils), features of iron deficiency (microcytosis and hypochromasia), features of IMHA (spherocytes, ghost cells, agglutination).
Clinical relevance: depends on underlying condition.”
What is this abnormal morphology?
Polychromatophils
Morphology: immature red blood cells that stain dark purple on Romanowsky stains (Wright’s, Diff-Quick) due to retained cytoplasmic RNA. Larger than normal red cells.
Commonly seen with: features of regenerative anemia (macrocytosis, anisocytosis, nucleated red blood cells)
Polychromatophils versus reticulocytes: both are immature red blood cells containing RNA. Reticulocytes stain blue with new-methylene blue. Polychromatophils stain purple with Romanowsky stains. Aggregate reticulocytes stain purple on Romanowsky stains so aggregate reticulocytes are polychromatophils. Punctate reticulocytes cannot be distinguished from normal red blood cells on Romanowsky stains.
Clinical relevance: increased polychromatophils (polychromasia) indicates that bone marrow is responding to anemia. Anemia is considered regenerative if sufficient polychromatophils are present. If a robust polychromatophilic response is not present in an anemic patient, it is important to evaluate a blood smear using new-methylene blue stain to detect reticulocytes. Horses do not release polychromatophils in response to anemia (they release macrocytes). Small numbers of polychromatophils may be normal in healthy dogs.”
What is this abnormal morphology?
Reticulocytes
Morphology: immature red blood cells that stain blue with new-methylene blue due to precipitation of retained cytoplasmic RNA. Aggregate reticulocytes are less mature with large amounts of RNA that form dark blue clumps or strands. Punctate reticulocytes are more mature with small amounts of RNA that form small blue dots.
Commonly seen with: features of regenerative anemia (macrocytosis, anisocytosis, polychromatophils, nucleated red blood cells)
Polychromatophils versus reticulocytes: both are immature red blood cells containing RNA. Reticulocytes stain blue with new-methylene blue. Polychromatophils stain purple with Romanowsky stains. Aggregate reticulocytes stain purple on Romanowsky stains stains so aggregate reticulocytes are also polychromatophils. Punctate reticulocytes cannot be distinguished from normal red blood cells on Romanowsky stains.
Clinical relevance: increased reticulocytes (reticulocytosis) indicates that bone marrow is responding to anemia. If a robust polychromatophilic response is not present in an anemic patient, it is important to evaluate a blood smear using new-methylene blue stain to detect reticulocytes. Anemia is considered regenerative if sufficient reticulocytes are present. A reticulocyte count (percentage or absolute count) quantifies the number of aggregate reticulocytes present (punctate reticulocytes are not included in the reticulocyte count because they are more mature and do not reflect current regeneration).”
What is this abnormal morphology?
Hypochromasia
Morphology: red blood cells that stain pain with increased central pallor and thin rim of hemoglobin (decreased hemoglobin content).
Look alike: torocytes (increased central pallor with normal thick rim of hemoglobin).
Commonly seen with: other features of iron deficiency (anemia, microcytes).
Clinical relevance: usually associated with advanced iron deficiency. May also be observed with other deficiencies (copper, vitamin B6) or toxicities (chronic lead poisoning). Hypochromasia can be associated with decreased mean corpuscular hemoglobin concentration (MCHC) on CBC.”
What is this abnormal morphology?
Torocytes
Morphology: red blood cells with increased central pallor and a normal thick rim of hemoglobin creating a “punched out” appearance.
Look alikes: codocytes (bullseye), hypochromasia (increased central pallor with thin rim of hemoglobin)
Clinical relevance: artifact with no clinical significance.”