Lymph Node Cytology

Question 1

What are the indications for lymph node sampling?

Answer 1

Lymphadenomegaly
Evaluation of metastatic disease
Classification of lymphoma

Question 2

Which structures drain to the submandibular LNs?

Answer 2

Head including rostral oral cavity

Question 3

Which structures drain to the prescapular LN?

Answer 3

Head caudal
Thoracic limb
Part of thoracic wall

Question 4

Which structures drain to the axillary LNs?

Answer 4

Thoracic wall

Deep structures of thoracic limb

Question 5

Which structures drains to the superficial inguinal LN?

Answer 5

Caudal abdomen 
Ventral half of abdominal wall
Penis
Prepuce
Scrotal skin
Tail
Ventral pelvis
Medial part of thigh and stifle

Question 6

Which structures drain to the popliteal LNs?

Answer 6

Distal to stifle

Question 7

What are the considerations when sampling LNs?

Answer 7

Submandibular alwaus some reactivity (close to mouth)
Aspirating very large LNs - necrotic, haemorrhagic centre
Smearing technique

Question 8

What should you consider when choosing to perform an aspirate vs biopsy?

Answer 8

Invasiveness, cost, turn around
Cell detail vs architecture
- Lymphoma
- Metastasis
Immunocytochemistry

Question 9

What are the 5 stages of a systematic approach to LN aspirates?

Answer 9

1. Evaluate quality of preparation
2. Scan entire slide on low mag (x4) to find best area
3. Assess cellular arrangement on low power
4. Decide if uniform or variable population
5. Fit into category based on proportion of cell types present

Question 10

How can you evaluate the quality of an aspirate preparation?

Answer 10

Adequate amount of intact cells
Adequate spread
Adequate staining

Question 11

What 5 categories do LNs fit into?

Answer 11

1. Normal
2. Hyperplastic/reactive
3. Lymphadenitis
4. Lymphoid neoplasia
5. Non-lymphoid neoplasia

Question 12

Which cells types would you find in LN aspirates?

Answer 12

- Small lymphocytes
1-1.5x RBC
- Medium lymphocytes
2-2.5x RBC
- Large lymphocytes
>3x RBC
- Plasma cell
- Macrophage
Inflammatory cells
Mast cells
Foreign cells

Question 13

How can you tell the difference between small, medium and large lymphocytes?

Answer 13

Small:
1-1.5x RBC
Chunky clumpy chromatin
Very small amount of cytoplasm

Medium:
2-2.5x RBC
Lighter as less chunky chromatin

Large:
>3x RBC

Question 14

What do plasma cells look like?

Answer 14

Abundant cytoplasm with white zone (golgi zone) next to nucleus

Question 15

What do normal LN aspirates look like?

Answer 15

Dominated by small, mature lymphocytes (>90%)

Low number of medium to large immature lymphocytes (<5-10%)

Occasional macrophages, rare neutrophils, eosinophils, mast cells etc

Question 16

What does a hyperplastic/reactive LN aspirate look like?

Answer 16

Similar population to normal but node is enlarged:

Increased % medium to large lymphocytes BUT <50%

Possible increased % plasma cells

Possible increased mitotic figures

ALWAYS look for reason for hyperplasia

Question 17

What does lymphadenitis look like on LN aspirate?

Answer 17

Increased % inflammatory cells

Neutrophils >5% neutrophilic

Eosinophils >3% eosinophilic

Macrophages

Also mast cell % increase

Question 18

What does lymphoid neoplasia look like on LN aspirate?

Answer 18

> 50% immature (medium to large) lymphocytes

Monotony - size varies but colour, chromatin and cytoplasma same

Not the appearance but the increase in numbers that count

Increased mitotic figures

Low numbers of small, mature lymphocytes

Psosible plasma cells

Question 19

What does a metastatic neoplasia look like on LN aspirate?

Answer 19

Presence of foreign cells (even if don’t have ample features of malignancy)

Need to examine all slides (small area)

Not finding metastatic cells doesn’t rule out

Question 20

What diagnostic techniques are availble for LNs?

Answer 20

PCR for T or B cell receptor arrangement

Flowcytometry

Immunocytochemistry