Lymph Node Cytology Flashcards
What are the indications for lymph node (LN) sampling?
Lymphadenomegaly
Evaluation of metastatic disease based on drainage
Classification of lymphoma
What are the LN drainage sites?
Submandibular = head
Prescapular = caudal head, thoracic limb, thoracic wall
Axillary = thoracic wall, deep thoracic limb + neck, thoracic + cranial abdominal mammary glands
Superficial inguinal = caudal abdominal + inguinal mammary glands, ventral abdominal wall, penis, prepuce, scrotal skin, tail, ventral pelvis, medial thigh + stifle
Popliteal = distal to stifle
Why should use of submandibular be avoided if other LNs enlarged?
Drains the mouth so can often be signs of infection present which can give mixed/inconclusive results
How should very large nodes be sampled?
Aspirate edges as often large necrotic centre to prevent contamination of abnormal cells and blood
What happens if you press too hard when smearing cells?
Free nuclei and no cytoplasm as cells are smashed
What happens if you don’t press hard enough when smearing cells?
Thick preparation where it is difficult to identify cells and evaluate them properly
How do you decide between aspirate and biopsy?
Invasiveness, cost, turn around time all less for aspirate
Cell detail vs architecture required
Immunohistochemistry required?
What is first assessed when looking at LN aspirates?
Low power evaluation of quality of preparation by looking at amount of intact cells, adequate spread ad adequate staining of slide
How is amount of intact cells evaluated?
If immature cells more lysed cells are common as they are more fragile
How is adequate spread of cells evaluated?
If thin areas not so good as good aspirates have lots of cells and are quite thick
How is staining assessed?
Thick areas tend to understain
Never evaluate understained areas as they all look like lymphoma
What does scanning on low power allow you to do?
Find best areas to spend time on
Assess cellular arrangement for foreign cells
Uniform population/variable population
What makes up a normal LN aspirate?
> 90% small mature lymphocytes
Low numbers of medium to large immature lymphocytes
Occasional macrophages, rare neutrophils/eosinophils/mast cells
What does a mature lymphocyte look like?
Size of nucleus 1-1.5 RBC, clumped chromatin, small amount of cytoplasm
What does a medium immature lymphocyte look like?
2-2.5 RBC nucleus, finely granular chromatin, occasionally prominent nucleoli, increased amount of light to deeply blue basophilic cytoplasm
