Lymph Node Cytology

Question 1

Indications for lymph node sampling

Answer 1

• lymphadenomegaly
• classification of lymphoma (histo)
• evaluating mets
  > based on drainage
• submandibular (head inc rostral oral cavity)
• pre scapular (head caudal pharynx and pinna, thoracic limb, part of thoracic wall)
• axillary (thoracic wall, deep structures of thoracic limb and neck, thoracic and cranial abdo mammary glands
• superficial inguinal (caudal abdominal and inguinal mammary glands, ventral half of abdo wall, penis, prepuce, scrotal skin, tail, ventral pelvis, medial part of this and stifle.)
• popliteal (distal to stifle)

Question 2

3 main considerations for LN sampling?

Answer 2

• submandibular often reactive d/t dental problems
• aspirating very large nodes (haemorrhaging, necrotic centre) stab lots
• smearing technique

Question 3

What are cells with no cytoplasm likely to be?

Answer 3

Free nuclei d/t cells being squashed

Question 4

Considerations of aspirate v biopsy?

Answer 4

• invasiveness, cost and turn around time
• cell detail v architecture (lymphoma, mets only present in some areas of LNs)
• immunocytochemistry (new technique, will see more in the future)

Question 5

How can you evaluate the quality of smear preparation?

Answer 5

• adequate amount of intact cells (immature lymphocytes very fragile, lysed cell common)
• adequate spread (thin areas)
• adequate staining (thick areas understain - NEVER INTERPRET UNDERSTAINED AREAS THEY LOOK LIKE LYMPHOMA!

Question 6

Outline stages of assessing LN aspirates

Answer 6

• scan. Low power to find best area
• look for foreign cells
• uniform v variable population (opposite of sarcoma/carcinoma where variable population shows malignancy)
• decide cell types present

Question 7

Are uniform populations of lymphocytes good?

Answer 7

NO BAD!!! Want variable population of lymphocytes of varying ages.
Cf. sarcoma/carcinoma where uniform population is good and variable population shows malignancy.

Question 8

What are the 5 LN classifications?

Answer 8

• normal
• hyper plastic /reactive lymph node
• lymphadenitis
• lymphoid neoplasia
• non-lymphioid neoplasia

Question 9

Outline what a normal LN would look like on cytology

Answer 9

> mostly small, mature lymphocytes (>90%)
- size of nucleus 1-1.5 RBC in diameter, clumped chromatin, small cytoplasm
low numbers of medium (2-2.5RBCs) to large (>3RBCs) immature lymphocytes (finely granular chromatin, occasional prominent nucleoli, ^ amount light/basophilic cytoplasm ( occasional macrophages, neutrophils, eosinophils, mast cells etc.

Question 10

Outline what a hyperplastic/ reactive LN would look like on cytology

Answer 10

• similar populations but node enlarged
• increase populations medium/large lymphocytes but less than 50%
• poss ^ plasma cells (small eccentric nucleus, clumped chromatin, abundant deeply basophilic cytoplasm a and Golgi zone (prominent perinucleur halo))
• poss ^ no. Mitotic figures
• always try to look for reason of hyperplastic/reactivity (metastatic tumour, organisms etc.)

Question 11

Outline how a LN biopsy affected by lymphadenitis would appear cytologically

Answer 11

> increased percentages of inflam cells

• neutrophils >5%
• eosinophils >3%
• macrophages (histocytic/macrophagic)
• combination of above, also mast cell % ^

Question 12

How can lymphoid neoplasia be distinguished on cytology?

Answer 12

> 50% immature (medium large) lymphocytes - monotony (not appearance but numbers)

• possibly ^ numbers of mitotic figures
• low numbers small mature lymphocytes
• +- plasma cells

Question 13

How can metastatic neoplasia be identified on LN smear ?

Answer 13

• presence of foreign cells (even if they don’t have features of malignancy)
• examine all slides
• not finding metastatic cells doesn’t rule it out

Question 14

Give 3 new techniques for diagnosing lymphoma

Answer 14

• PCR for T and B cell receptor re-arrangement (clonality - not every clonal population is neoplasia most likely)
• flowcytometry (immunophenotyping)
• immunocytochemistry

Question 15

What would you expect to see with an FNA of a neutrophilic, macrophagic lymphadenitis?

Answer 15

• majority neutrophils and macrophages (not neccesarily phagocytic but v N:C ratio peripheral nucleus, no signs of malignancy), occ med lymphocytes, small mature lymphocytes, mitotic figure and a plasma cell

Question 16

What would you expect to see with an FNA of a salivery gland

Answer 16

• RBCs in rows d/t mucin (WINDROWING)
• large foamy epithelial cells repsonisble for mucin production
• large clumps blue cells (ductal epithelial cells)

Question 17

What would you expect to see with an FNA of a metastasised oral melanoma?

Answer 17

• small lymphocytes
• foreign cells iwth brown/green pigment (melanin)
• can be spindle cells (cytoplasmic tail) round or epithelial cells

Question 18

Are oral and digital melanomas commonly malignant?

Answer 18

YES usually very ,alignant

- recently discovered new subgroup not as malignant

Question 19

What would you expect to see with an FNA of a hyperplastic LN

Answer 19

• majority small lymphocytes, some medium

Question 20

How do cat RBCs differ to dogs?

Answer 20

Cats smaller SO lymphocytes appear relativley larger !!

- small lymphocytes can be ~2x RBC

Question 21

What would you expect to see with an FNA of a severely necrotising fibrinosupparative lymphadenitis?

Answer 21

• ltos oflysed, messy cells with only outlines left
• very thick proteinaceous background
• granular pink grey debris
• rare neutrophils (though lysed cells may have been neutrophils)
• essentially big pile of pus
• bacteria not necessarily seen