Lymph Node Cytology Flashcards
Indications for lymph node sampling
- 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)
3 main considerations for LN sampling?
- submandibular often reactive d/t dental problems
- aspirating very large nodes (haemorrhaging, necrotic centre) stab lots
- smearing technique
What are cells with no cytoplasm likely to be?
Free nuclei d/t cells being squashed
Considerations of aspirate v biopsy?
- 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)
How can you evaluate the quality of smear preparation?
- 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!
Outline stages of assessing LN aspirates
- 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
Are uniform populations of lymphocytes good?
NO BAD!!! Want variable population of lymphocytes of varying ages.
Cf. sarcoma/carcinoma where uniform population is good and variable population shows malignancy.
What are the 5 LN classifications?
- normal
- hyper plastic /reactive lymph node
- lymphadenitis
- lymphoid neoplasia
- non-lymphioid neoplasia
Outline what a normal LN would look like on cytology
> 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.
Outline what a hyperplastic/ reactive LN would look like on cytology
- 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.)
Outline how a LN biopsy affected by lymphadenitis would appear cytologically
> increased percentages of inflam cells
- neutrophils >5%
- eosinophils >3%
- macrophages (histocytic/macrophagic)
- combination of above, also mast cell % ^
How can lymphoid neoplasia be distinguished on cytology?
> 50% immature (medium large) lymphocytes - monotony (not appearance but numbers)
- possibly ^ numbers of mitotic figures
- low numbers small mature lymphocytes
- +- plasma cells
How can metastatic neoplasia be identified on LN smear ?
- 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
Give 3 new techniques for diagnosing lymphoma
- PCR for T and B cell receptor re-arrangement (clonality - not every clonal population is neoplasia most likely)
- flowcytometry (immunophenotyping)
- immunocytochemistry
What would you expect to see with an FNA of a neutrophilic, macrophagic lymphadenitis?
- 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
