Erythrocytosis and Polycythemia/Lymph Node Cytology Flashcards
describe erythrocytosis and polycythemia
erythrocytosis: increase in RBC mass (HCT/PCV, RBC count, and/or Hgb)
polycythemia: many cells in the blood
-most pathologists use this term only for neoplasia
why is more blood bad?
- increases blood viscosity, causing sludging of RBCs in vessels
- leads to impaired blood flow:
-decreased tissue oxygenation
-congested mucous membranes
-dilated retinal vessels
-seizures
describe breed specific differences in RBC mass
some breeds have a higher RBC mass in health
-sighthounds, greyhounds, some dachshunds
-racing horses, warm-blooded breeds
describe erythropoietin
- primary hormonal regulator of RBC production
- produced by the fetal liver and the adult kidney
- upregulated by renal hypoxia (NOT RBC mass)
-anemia
-poor renal perfusion
-poor oxygenation of blood
what are the 2 types of erythrocytosis?
- relative:
-NOT a true increase in RBC mass
-2 big causes:
–dehydration: decreased plasma volume (hemoconcentration); history, PE findings, increased protein, USG, asotemiz
–splenic contraction: excitable animal (epi response), redistribution of RBCs from spleen, common in cats and horses - absolute: TRUE increase in RBC mass
-primary: low/normal Epo, polycythemia vera
-secondary: increased Epo
–appropriate: hypoxia induced (high alt, lung disease, right to left cardiac shunts)
–inappropriate: no systemic hypoxia (renal diseases, epo-secreting tumors, exogenous)
describe dehydration causing relative erythrocytosis
- most common cause of mild to moderate erythrocytosis
- NOT an absolute increase in RBC mass, just a decrease in plasma volume
- PE findings:
-dry or tacky MM, skin tent
4, lab findings:
-increased proteins (TP and albumin)
-highly concentrated urine (high USG)
-possible pre-renal azotemia (increased urea and creatinine)
- tx: rehydrate the patient and recheck
describe splenic contraction causing relative erythrocytosis
- no dehydration
- NOT an increase in RBC mass; RBCs are redistributed into circulation from splenic contraction
- transient and secondary to fear, excitement, exercise
- seen more frequently in cats and horses than in dogs
- may also see a lymphocytosis (epi-induced)
describe absolute erythrocytosis
- due to a true increase in RBC mass
-all causes of a relative erythrocytosis must be excluded (calm, hydrated animal) - primary (rare): EPO independent (EPO is normal or low)
-known as polycythemia vera: neoplastic proliferation of mature RBCs independent of EPO
-RBCs are morphologically unremarkable
-diagnosis of exclusion - secondary: EPO dependent (increased)
a. appropriate: EPO production is increased secondary to hypoxia or hypoxemia
-causes: heart disease, lung disease, high altitudes
b. inappropriate: EPO production increased without systemic hypoxia/hypoxemia
-causes: renal lesions causing local hypoxia, non-renal tumors that produce EPO or EPO-like substances, exogenous (doping)
when would you aspirate a lymph node
- lymphadenomegaly: enlargement of one or multiple lymph nodes
-detected via palpation, radiography, or ultrasonography - eval for presence of metastatic disease/staging
list the 6 commonly sampled lymph nodes, where they are located, and drainage features
- mandibular: ventral angle of the jaw
-drainage: most of the head, including rostral oral cavity - prescapular/superficial cervical: cranial shoulder
-caudal part of the head (phraynx pinna), most of the thoracic limb and part of thoracic wall - axillary: caudal and medial to shoulder joint
-most of thoracic wall, deep structures of the thoracic limb and neck, cranial mammary glands - superficial inguinal: furrow between abdominal wall and medial thigh
-caudal mammary glands, ventral half of abdominal wall, penis, prepuce, scrotum, tail, ventral pelvis, medial thigh, stifle - popliteal: back of stifle
-area distal to the stifle - medial iliac: near caudal vena cava and aorta (internal)
–skin of pelvic area, pelvic limb distal intestinal and urogenital system
describe making a diagnostic smear
- goal: thin layer of intact cells, rapidly air-dried slides
- methods: impression smears, woodpecker or needle off, fine needle non-aspirate, FNA
- squash prep technique: allows for proper dispersion of cells and improves diagnostic ability
- avoid making a splat or shotgun blast smears
-limits diagnostic ability as it creates dense smears and high numbers of lysed cells
describe sample eval
- cellularity versus degree of blood contamination
- eval cell types present, their morphology, and relative proportions of each cells type
- determine if sample is actually lymph node
-could be salivary epithelium if sample from mandibular lymph node
-adipose tissue: if aspirated perinodal fat
-could be muscle
describe sizing of lymphocytes and cytomorphology
- small lymphocytes:
-smaller than a neutrophil, scant basophilic cytoplasm, condensed/closed chromatin with indistinct nucleoli - intermediate lymphocytes:
-similar in size to a neutrophil, low to moderate amounts of basophilic cytoplasm, lighter chromatin - large lymphocyte:
-larger in size than a neutrophil, low to moderate amounts of basophilic cytoplasm, finely stippled (open) chromatin often with visible nucleoli
describe a normal lymph node
- majority of small lymphocytes (>90%) with low numbers of intermediate and large lymphocytes (<10%)
- low numbers of other cell types may also be present
-macrophages: may contain hemosiderin (breakdown of heme pigment)
-plasma cells: produce immunoglobulin
-mast cells: should be individualized - lysed cells/artifact:
-streaming nuclear debris or light pink nuclear fragments that lack cytoplasmic borders - lymphoglandular bodies: cytoplasmic fragments from lysed lymphocytes
-routinely present in normal tissue but may be increased with lymphoma
describe differentials for an enlarged lymph node
- reactive or hyperplastic lymph npde
- inflammation/lymphadenitis
- neoplasia
-primary: lymphoma
-metastatic: carcinomas, other round cell tumors, melanoma, sarcomas
