RBC Morphology + Inclusions Flashcards
Reticulocytes
slightly immature RBCs that contain residual RNA + not fully completed Hgb synthesis
for most species, may complete maturation within spleen or peripheral blood
healthy cattle + healthy/ill horses, reticulcytes mature completely within bone marrow before release
stain light blue gray/purple with romanowsky stains
Polychromasia
reticulocytes without enough RNA to result in visually perceptible blue purple color = polychromatophils
overall presence of this population in peripheral blood = polychromasia
all polychromatophils are reticulocytes but not all reticytes will be visible as polychromatophils
Polychromatophils v Reticulocytes
Polychromatophils:
- romanosky stain
- purple in color relative to red
- immature RBCs 🡒 less Hgb + more RNA
- often larger than mature RBCs + may be wrinkled/folded
Reticulocytes:
- New Methylene Blue (NMB) stain 🡒 causes aggregation of residual RNA 🡒 dark, blue granular material in RBCs
- easier to visualize + quantify (manual count)
- flow cytometry to quanity (automated)
Anisocytosis
Variation in apparent size across a population of erythrocytes
- may be d/t presence of macro/microcytes or both
- includes 🡑 numbers of polychromatophils/reticulocytes
Macrocytes
larger than normal RBCs
if larger RBCs stain blue gray to purple then these represent polychromatophils
if mature, normochromic macrocytes are present, consider:
- sample age (ex vivo swelling)
- possible regeneration in anemic horses
- FELV+ cats
- hereditary macrocytosis of poodles
Microcytes
smaller than normal RBCs
possible causes:
- iron deficiency anemia
- vascular anomalies + severe liver disease
- heinz body remnants
- fragmentation of RBCs
- breed
may be seen in some healthy dogs breeds of east Asian origin
Hypochromasia
🡓 cytoplasmic staining of RBCs, with 🡑 area of central pallor
Causes:
- many immature erythrocytes produced in regenerative anemia
- iron deficiency 🡒 common in domestics
- birds 🡒 lead toxicity, inflammation
Poikilocytosis
umbrella term for RBCs that deviate from normal morphology for species, regardless of specific shape change
ideally, describe + quantify specific shape changes
no single change is pathognomic for specific dz
Acanthocytes
unevely spiky erythrocytes with irregular membrane projections
Presumptive mechanisms:
- RBC trauma/fragmentation
- 🡑 cholesterol:lipid ratio in RBC membrane
Reported with:
- some types of cancer
- liver disease
- iron deficiency anemia
- trauma within vascular system
- altered lipid metabolism
- normal in young catttle + young goats
Codocytes
central area of Hgb seperated from peripheral Hgb by a clear area =** target appearance**
have more membrane than usual, relative to cytoplasm
- 🡑 lipid/cholesterol +/or 🡓 cytoplasmic volume
Causes:
- polychromatophils
- liver disease
- iron deficiency anemia
Echinocytes
spiculated RBCs with evenly-spaced, uniform membrane projections
common in healthy cats + pigs
Causes:
- ex vivo artifact from changes in temp, pH or drying (most common)
- snake envenomation
- uremia
- electrolyte depletion
- lymphoma
- doxorubicin toxicity
- glomerulonephritis
Keratocytes
have 1-2 cell membrane projections created from ruptured vesicle
Causes:
- trauma within vascular system
- oxidative damage
- iron deficiency anemia
Blister cells: RBCs where vesicle still attached
other causes:
- liver diseases (cats)
- doxorubicin toxicity (cats)
- myelodysplastic syndrome (dogs)
Ovalocytes
Oval RBCs
normal in camlids + non-mammals (avian/reptiles/amphibians)
Dogs:
- myelofibrosis
- myelodysplastic syndrome (MDS)
- rare hereditary/congenital diseases of dogs
Cats:
- liver disease
- portosystemic shunt (PSS)
- doxorubicin administration
may be oberseved in iron deficiency
Shistocytes
irregular RBC fragments
d/t trauma, including tortuous vasculature, intravascular fibrin strands (DIC), turbulent blood flow
Reported with:
- disseminated intravascular coagulopathy (DIC)
- hemangiosarcoma
- congestive heart failure (CHF)
- vasculities, glomerulonephritis
- chronic doxorubicin toxicity
- myelofibrosis
Spherocytes
small, dark red RBCs that completely lack central pallor
🡓 membrane w/ normal cytoplasmic volume
appear smaller, compared with normal RBCs
**
can only be reliably identified in monolayer blood smear of DOGS**
Causes:
- IMHA 🡒 most common
- after transfusion with stored RBCs
- removal of heinz bodies, epicellular hemoparasite, damaged membrane, etc. by splenic macrophages
- snake envenomation
- bee stings
RBC Inclusions
- basophillic stippling
- siderotic (iron) inclusions
- howell-jolly bodies
- heinz bodies
- nucleaded erythrocytes (nRBCs)
- some hemoparasites
- viral inclusions
Basophillic Stippling
- diffuse basophillic punctuate inclusions
- due to residual aggregates of ribosomes
- observed on romanowsky-stains
Observed in:
- regenerative anemias 🡒 especially ruminants
- lead toxicity 🡒 any species
Siderotic Inlusions
focal, blue/brown, rounded/irregular structures within RBC cytoplasm
inclusions represent accumulated iron
Reported:
- hemolytic anemias
- lead toxicity
- dyserythropoiesis
- myeloproliferative diseases
- chloramphenical tx
- idiopathic
Howell-Jolly Bodies
small (2-3u) spherical, dark blue/purple nuclear remnants
nuclear material left behind when nucleus is expelled
- must differentiate from parasitic organisms
often removed by spleen
Seen in:
- low numbers not uncommon in healthy animals
- regenerative anemia
- splenectomized animals
Heinz Bodies
aggregates of denatured Hgb caused by oxidative damage
Appearance:
- round, protuding structures from side of RBC membrane
- small, pale or slightly refractile cytoplasmic spots when sitting on top of RBC
appear light pink/red with romanowsky stain
- light blue with NMB
up to 5% heinz bodies can be seen in healthy cats
Dogs:
- acetamoniphen
- allium spp. (onions/garlic/chives)
- zinc
- more
Cats:
- acetamoniphen
- allium spp. (onions/garlic/chives)
- more
Horses:
- red maple leaves
- more
Ruminants
- selenium/copper defficiency
- ryegrass + lush winter rye
- copper toxicosis (sheep/goats)
- more
Nucleated Erythrocytes (nRBCs)
should be nucleated in birds, reptiles, fish, etc.
metarubricytes (most common), rubricytes, or earlier precursors in mammals
when observed in higher-than normal numbers in mammalian peripheral blood, must determine if appropriate v inappropriate
Rouleaux
linear association of RBCs (stack of coins)
Causes:
- can be common in healthy animals of certain species (horses + cats)
- can be secondary to 🡑 proteins in plasma
should disperse with addition of physiologic saline to an unstained wet mount of whole (anticoagulated) blood
Agglutination
irregular clumpling/aggregates of RBCs
- more than 3-5 RBCs in aggregate = agglutination
- does’t disperse with addition of physiologic saline
if present, concerning for antibody or complement coating the RBC surface, allowing for cross-linking of nearby RBCs
- thus often signifies IMHA
