Practical Hematology Leukocytosis Wendy Blount, DVM

Practical Hematology Anemia 101 Blood Loss Anemia Hemolysis Non-Regenerative Anemia Transfusion Medicine Polycythemia Bone Marrow Disease Coagulopathy Central IV Lines Leukophilia Leukopenias Splenic Disease

Leukocytosis Total WBC x %cell = absolute Use WBC percentages only to calculate absolutes Count: Neutrophils - Bands Lymphocytes Monocytes Eosinophils Basophils Look at the blood smear for every CBC with abnormalities No automated Diff identifies band cells Many fail to identify basophils

Leukocytosis Hypersegmented neutrophil More than 5 nuclear lobes Prolonged inflammation

Leukocytosis lymphocyte

Anaplasma phagocytophilum Leukocytosis Anaplasma phagocytophilum

Leukocytosis monocyte

Leukocytosis Band neutrophil

Leukocytosis monocyte

Leukocytosis Segmented neutrophil

Leukocytosis RBC - Basophilic stippling

Leukocytosis Giant platelet

Leukocytosis polychromatophil

Leukocytosis Lymphocyte

Leukocytosis basophil

RBC – distemper inclusions Leukocytosis RBC – distemper inclusions

RBC – Howell Jolly Bodies Leukocytosis RBC – Howell Jolly Bodies

Leukocytosis Eosinophil

Leukocytosis monocyte

Leukocytosis Histoplasma spp

Leukocytosis Mast cell

Leukocytosis eosinophil

Leukocytosis basophil

Leukocytosis Mast cell

Leukocytosis Segmented neutrophil

Leukocytosis basophil

Leukocytosis monocyte

Counted in the WBC, not the RBC Leukocytosis nRBC Counted in the WBC, not the RBC

Leukocytosis eosinophil

Leukocytosis toxic band neutrophil Dohle bodies

Leukocytosis monocyte

Leukocytosis Segmented neutrophil

Leukocytosis monocyte

Leukocytosis Hepatozoon spp gamont

Leukocytosis Lymphocyte

Leukocytosis band eosinophil

Leukocytosis Segmented neutrophil

Leukocytosis Activated lymphocyte

Leukocytosis Ehrlichia morulae

Leukocytosis Segs vs. Bands vs. Monocytes Nucleus shape 1 indentation indicates seg, bands have no dents Bands parallel sides, segs & monos don’t Segs thinner nucleus, bands fatter, monos thin to round nucleus Seg nucleus longer than band Nucleus color – segs darkest, monos lightest Chromatin pattern – segs most clumps (heterochromatin), then bands, monos lacy Cytoplasm color – segs/bands light, monos lavender

DDx Neutrophilia Infection Sterile inflammation Necrosis Stress/corticosteroids Exercise/epinephrine Neutrophilic leukemia Neoplasia (rare) CGL

DDx Necrosis Pancreatitis Pansteatitis Immune mediated disease Caustic substances Venomous bites and stings Neoplasia Ischemia

Left Shift Left shift indicates acute, intense inflammation >1000/ul bands/nonsegs = left shift 300-1000/ul = mild left shift Rarely Pelger-Huet Anomaly or granulocytic leukemia immature hyposegmented (round nuclei) neutrophils indicates a more intense inflammation Metamyelocytes Myelocytes promyelocytes Peripheral myeloblasts often indicate leukemia

Left Shift Left shift indicates acute, intense inflammation >1000/ul bands = left shift 300-1000/ul = mild left shift Rarely Pelger-Huet Anomaly or granulocytic leukemia immature unsegmented neutrophils indicates a more intense inflammation Metamyelocytes Myelocytes promyelocytes Peripheral myeloblasts often indicate leukemia

Toxic Neutrophils Changes in the cytoplasm (any or all) Dohle Bodies & Toxic granulation Cytoplasmic basophilia Cytoplasmic vacuolation Rarely giant toxic neutrophils Indicate severe disease and worse prognosis

Toxic Neutrophils DDx toxic neutrophils - toxemia Sepsis – pyometra, parvovirus, pneumonia Viral infection – feline URI Toxic disease – acute renal failure Necrosis – pancreatitis, neoplasia, etc. Immune mediated disease – IMHA Massive systemic inflammation – DIC, SIRS, peritonitis Toxic neutrophils appear in cats with disease that is relatively less severe than that causing toxic neutrophils in dogs

Chronic Inflammation Monocytosis indicates inflammatory process is at least 10 days old Elevated globulins also indicate chronicity Left shift rarely seen WBC can be normal with significant chronic inflammation Other clues: Recurring fever Increased rouleau formation Vasculitis and other secondary immune mediated disease can develop with time Normal leukogram does not rule out significant infection or inflammation

Prognosis for Neutrophilia Poor prognostic indicators Progressive degenerative left shift More nonsegs than segs Most common cause is sepsis WBC > 60,000/ul correlated with increased risk of sudden death in dogs Extremely high mature neutrophilia “Leukemoid response” Marked toxic changes in the neutrophils Graded 1+ to 4+ Severe persistent lymphopenia Sustained stress on the body Magnitude of feline neutrophilic response is less than canine

Iron deficiency anemia DDx Increased nRBC Heat Stroke Sepsis Bone Marrow Disease Splenic Disease Post Splenectomy Regenerative anemia Iron deficiency anemia

DDx Leukemoid Response Internal abscess Pyometra, Bacterial prostatitis Discospondylitis Pyothorax, septic peritonitis Pancreatic/hepatic abscess Neutrophil count often will continue to accelerate for at least one week after resolving abscess IMHA ( Ralph ) Neoplasia Hepatozoon canis CLAD of Irish Setters – Canine Leukocyte Adhesion protein Deficiency

Stress/Corticosteroid Response Mild to moderate neutrophilia <40,000/ul in the dog <30,000/ul in the cat Lymphopenia Eosinopenia (overlaps with normal) Monocytosis (>2,500/ul) in dogs Mature neutrophilia Increased hypersegmented segs “right shift” Onset within 4-13 hours Resolves within 24 hours

Epinephrine/Exercise Response Mild to moderate neutrophilia WBC move from marginalized to circulating Lymphocytosis (6-15,000/ul) Especially cats Increased HCT Splenic contraction Marked Neutrophilia >50,000/ul in the dog, >30,000 in the cat Severe Neutrophilia >100,000/ul in the dog, >50,000 in the cat

Work-Up for Occult Infection FeLV/FIV test in cats Heartworm test in dogs CBC General health profile Electrolytes and venous blood gases Thoracic and abdominal x-rays GlobalFAST®, Abdominal ultrasound Urinalysis and urine culture Look especially hard for infection if: Toxic neutrophils Degenerative left shift Pronounced rouleaux

Work-Up for Occult Infection Echocardiogram if murmur “to and fro” murmur at left heart base bounding pulses Blood culture when febrile use ARD (antimicrobial removal device) if on antibiotics 2 samples several hours apart Collect aseptically CSF tap if neck/back pain or CNS deficits Joint taps if joint swelling or shifting lameness CPK if muscle pain Muscle biopsies or PCR if Hepatozoon suspected or increased CPK

DDx Monocytosis Chronic infection >10 days Necrosis Infection viral (especially FIP) Fungal Mycobacterial L-form, mycoplasma, Ureaplasma Parasitic Tissue foreign body Neoplasia Immune mediated inflammation Corticosteroids (lymphopenia, eosinopenia)

DDx Lymphocytosis Stress/epinephrine response Chronic infection (activated lymphocytes) Viremia Ehrlichia spp., Anaplasma spp. Toxoplasma gondii Immune mediated disease (esp feline IMHA) Recent vaccination Lymphoid neoplasia Addison’s Disease (5-10%)

Lymphocytosis Lymphocyte

Lymphocytosis Activated lymphocyte

Activated lymphs Atypical cells Immunoblast ALL CLL CGL

Lymphocytosis Activated lymphocytes – normal response aka reactive lymphocytes, immunocytes, variant lymphocytes Large, immunostimulated lymphocytes Dark blue cytoplasm with perinuclear clear zone (making IgM & IgG) Irregular, scalloped or cleaved nuclei Present with lymphoid hyperplasia Immunoblasts – marked inflammation aka blast transformed lymphocytes Lighter, more lacy chromatin in large nucleus Prominent nucleoli or nucleolar rings Atypical lymphocytes – usually malignant Characteristics of malignancy basophilic cytoplasm, heterochromic nuclei Large and atypical nucleolus Immature granular chromatin Uniform population

Puppies and kittens have higher lymphocyte counts Lymphocytosis Puppies and kittens have higher lymphocyte counts And more immunoblasts Adult dogs >2 years – lymphs <1000/ul 8-24 month puppies – 1000-1500/ul 3-6 month puppies – 1,500-2,000/ul

>5,000/ul – hypereosinophilia Strong eosinophilic response Eosinophils of sight hounds stain poorly – look like segs Rottweiler and GSD have higher reference range

DDx Eosinophilia Infection Allergy/asthma Immune mediated disease Parasitic infection of soft tissues Insect bites, parasitic enteritis Fungal Viral – FeLV Streptococcus, Staphylococcus spp. Allergy/asthma Immune mediated disease Hypereosinophilic syndrome - Rottweilers, cats Eosinophilic granuloma – huskies, malamutes, Cavalier King Charles spaniels Eosinophilic meningioencephalitis - Rottweilers PIE, eosinophilic pneumonia – huskies, malamutes

DDx Eosinophilia Mast Cell Tumor Other neoplasia Lymphoma Mucinous carcinoma fibrosarcoma Eosinophilic leukemia (rare) Canine estrus

DDx Basophilia Basophils can be difficult to identify Mistaken for monocytes or eos Parasites Allergy Mast Cell Tumor Lipemia Basophilic leukemia (very rare)

Leukemia Malignant blood cells (usually blasts – atypical cells) in circulation Or >20-30% malignant blood cells (usually blasts) in the marrow Often accompanied by cytopenias in other cell lines Clinical signs Hepatosplenomegaly Lymphadenopathy (FNA can be diagnostic) Fever, weight loss if acute Symptoms of cytopenias

Leukemia Cell lines of leukemia Acute undifferentiated (stem cell) Erythroleukemia (RBC) Myelomonocytic (monos & grans) Granulocytic - Neutrophilic, Eosinophilic, Basophilic Monocytic Megakaryocytic Lymphoproliferative Leukemia Lymphoblastic (ALL) Lymphocytic (CLL) Plasma Cells (multiple myeloma) Mast Cells

Leukemia Types of leukemia Aleukemic leukemia – no cancer cells in circulation; just in bone marrow Subleukemic leukemia – small amounts of cancer cells in circulation Leukemic leukemia – many cancer cells in circulation Maturity of leukemia Acute leukemia – proliferation of blasts, tends to be more severe Chronic leukemia – proliferation of more mature blood cells, tends to be less severe

Leukemia Pre leukemia (Myelodysplasia) Bone marrow dysplasia, with maturation arrest Usually presents as cytopenia of the affected cell line Causes FeLV folate deficiency (B12 in giant schnauzers) Drug and toxin exposure Sometimes responds to treatment with prednisone and cell line stimulators (Epogen®/ProCrit®, Neupogen®) Multiple CBCs over time to monitor for leukemic leukemia

Leukemia Lymphoproliferative Disease Arises from the lymph nodes or other organs with reticuloendothelial function Spleen, liver, skin Thymus, bronchial-associated lymphoid tissue, GALT Very little lymphoid production in marrow Myeloproliferative Disease Arises from the bone marrow or other organs that can undergo EMH Spleen Rarely other organs

Leukemia CGL – chronic granulocyte leukemia (rare) No atypical cells as seen with acute leukemias Bands sometimes seen (left shift) Lymphadenopathy LN cytology can be diagnostic – EMH with very rare myeloblasts Liver and spleen may be similar Oddly, bone marrow aspiration is often not diagnostic – resembles myeloid hyperplasia Need bone marrow biopsy Dogs are often not sick

Lysosomal Storage Diseases Congenital enzyme defects cause accumulations of metabolites in cells Mucopolysaccharidosis (MPS) & many others Progressive CNS disease Seizures eventually become uncontrollable Some affected children are controlled with ketogenic diet And/or musculoskeletal disease (dwarfism) And/or corneal dystrophy Accumulations can be seen on manual diff CBC

Acknowledgements Chapter 2: The Complete Blood Count, Bone Marrow Examination, and Blood Banking Douglass Weiss and Harold Tvedten Small Animal Clinical Diagnosis by Laboratory Methods, eds Michael D Willard and Harold Tvedten, 5th Ed 2012 Chapter 4: Leukocyte Disorders Harold Tvedten and Rose Raskin