Cytology of tumours

When is cytology indicated?

• Lesion (nodule, mass, plaque) palpable externally or seen on imaging

• Organomegaly

• Cavitary effusion

• Cancer staging (lymph nodes, liver, spleen, BM)

• Pyrexia of Unknown Origin

What can cytology tell us and not tell us?

Can tell us:

• Inflam present

• neoplasia present

• If lesion is benign or malig

• Type of neoplasia

• Test of choice for bone marrrow exam

Cannot tell us:

• If hyperplasia or adenoma

• If reactive fibroplasia or sarcoma

• Type of neoplasia in poorly differetiated tumours —> may need confirmation with histopath

What are the advantages & limitations of cytology?

How do you approach evaluation of a cytological slide?

• Macroscopic —> labelling & smear quality

• Microscopic —> 10x to assess quality & find sweet spot (thin region w/ intact cells & good cellular detail)

• Then ID cell populations on 40-100x

sweet spot = can see nuclei & cytoplasm of cells

List some of the common sample quality issues in cytology

• Too thick —> repeat staining & incr staining time

• Insufficient staining time

• Inadequate drying prior to staining —> should be air-dried promptly

• Nuclei no longer “pop out”

• Staining time too high —> tailour staining time to sample cellularity (high cellularity, incr time)

• Incr aspiration pressure —> repeat aspiration w/ needle-only technique

• Incr pressure during smearing —> repeat applying less pressure

• Smear dried slowly

  • Cells balled up & impossible to ID

  • should rapidly air dry or use hair drier

List the common cytology artefacts

separate biopsy & cytology slides so no formalin artefact on cytology

Compare the general features of inflam to neoplasia on cytology

NB. Can often get both —> neoplasias can get inflamed

List some examples of neoplasias that often become inflamed

• SCC

• Mammary carcinoma

• Fibrosarcoma

• Mast cell tumour

Is this inflammation or neoplasia?

Mixed inflammation

Is this inflammation or neoplasia?

• Neoplasia (from a lymphoma)

  • Monomorphic population of large cells —> can see mitosis

What are the categories of inflam & their poss causes?

• Neutrophilic

  • Immune-mediated conditions, irritants (bile, urine), bacterial, protozoal or fungal infection

• Histiocytic/ macrophagic

  • FB reactions, fungal infection, certain bacterial infections, such as Mycobacterium

• Mixed

  • FB reactions, fungal infection, specific bacteria (e.g. nocardia, actinomyces)

• Eosinophilic

  • Hypersens reactions, parasites, fungi, insect bites, cancer (e.g. mast cell tumours)

• Lymphocytic/ lymphoplasmacytic

  • Antigenic stimulation, viral infections or chronic inflam

How can you categorise tumours?

What are the types of tumours based on cytomorphology?

How do you differentiate benign and malignant tumours on cytology?

Recall the criteria of malignancy

• Pleomorphism

• High or variable nuclear:cytoplasmic ratio

• Anisokaryosis

• Coarse chromatin

• Nucleolar changes

• Nuclear molding

• Multinucleation

• Abnormal mitotic figures

At least 3 to call it malignant (nuclear critera = more severe)

What is pleomorphism?

• Variation in size, shape or maturation state of cells & nuclei

What is anisokaryosis?

• Variation in nuclear size between cells of similar origin

• High or variable nuclear:cytoplasmic ratio between cells of similar origin

What is coarse chromatin?

• Ropy chromatin or clumping of nuclear chromatin is common in immature cells

What criteria of malignancy is being shown here?

• Nuclear moulding —> abnormal nuclear shape related to rapid growth of cells in which tight cell spacing occurs w/p normal crowd inhibition

What is being shown here?

Multinucleation

• Two or more nuclei occupy same cell

NB. Binucleation may be found in hyperplasia of some tissues

What criteria of malignancy is being shown here?

Abnormal mitotic figures

• Abnormal chromosomal fragments may appear w/ uneven length & as isolated fragments (lag chromatin)

• Incr numbers may be suggestive but not definitive for malignancy

What are the features of an epithelial tumour?

• Tight clumps or sheets —> tight junctions (desmosomes)

• Large, round to polygonal cells with distinct cytoplasmic borders

• Nuclei round to oval

Give some examples of epithelial tumours?

• Transitional cell carcinoma

• Lung carcinoma

• Sebaceous adenoma

What are the features of a sebaceous adenoma:

• Clinically

• Cytologically?

• Clinically —> raised cauliflower alopecic lesion

• Cytologically —> cluster of sebocytes w/ foamy cytoplasm and small, dense, centrally placed nucleus

  • NB. cannot differentiate from hyperplasia on cytology

What are the features of perineal (hepatoid) gland tumours?

• Ass. with intact male dogs (androgen dependency) but can affect all

• Perianal region, also tail, perineum, prepuce, thigh, dorsal or ventral midline

• Sheets of cell that look like hepatocytes

  • large oval cells

  • abundant, finely granular, pinkish-blue cytoplasm

  • round nucleus w/ single prominent nucleolus

    

• A few 'reserve' cells (Small basophilic cells w/ high N:C ratio

  

How do SCC present clincially?

• Solitary / multiple; proliferative / ulcerative

  • Limbs —> dog

  • Pinnae / face —> cats

• Locally invasive & may metastasise to regional LNs & digits (highly malignant)

How do SCC present cytologically?

• Large polygonal cells w/ variable tendency to cohesion

• Typically marked pleomorphism

• Perinuclear vacuolation

• Often 2° neutrophilic inflm

How does a mammary carcinoma present cytologically?

• Background w/ blood, basophilic proteinaceous material, lipid and foam cells

• Cells arranged in sheets, clusters or acini

• Round to polygonal cells w/ round to oval nuclei & basophilic cytoplasm

• Mod-marked pleomorphism

• Poss incr mitotic activity

usually require histopath for definitive diag

What are the features of mesenchymal tumours?

• Cells usually exfoliate individually or in aggregates w/ matrix

• Oval, stellate or fusiform often w/ indistinct cytoplasmic borders

• Samples often poorly cellular

• Nuclei oval to elongate

List some examples of mesenchymal tumours

• Soft tissue sarcoma

  • = Fibrosarcoma, liposarcoma, leimyosarcoma, perivascular tumours, rhabdomyosarcoma etc.

• Haemangiosarcoma

• Fibroma

What is this showing?

Soft tissue sarcoma

(difficult to distinguish from reactive fibroplasia —> need histopath for grading & ID of specific type)

What tumours is being shown here?

Fibrosarcoma

What mesenchymal tumour is being shown here?

Lipoma (cannot distinguish from normal subcut adipose tissue —> alcohol fixatives may dissolve fat)

What are the features of osteosarcoma?

• Round to spindle-shaped cells w/ basophilic cytoplasm & eccentrically placed nucleus w/ prominent nucleoli

• Osteoclasts (large multinucleated cells) might be present

• Pink extracellular matrix (osteoid) produced by cells may be present

What are the features of round cell tumours?

• Cells exfoliate individually

• Generally round cells w/ distinct borders

  • nuceli round to indented

• Samples moderately cellular

List some examples of round cell tumours

• Transmissible venereal tumour

• Mast cell tumour

• Lymphoma

• Plasmacytoma

What are the clinical features of a histiocytoma?

• Dome-shaped, alopecic, may be ulcertaed

• Tends to regress in a few wks

• Often (but not only) in young dogs

What are the cytological features of histiocytoma?

• Oval discrete cells w/ round to oval nuclei & abundant clear to lightly basophilic cytoplasm

• Variable numbers of small lymphocytes (common in regressing lesions —> sometimes can predom(^)

Describe the features of plasmacytomas

• Cutaneous plasmacytoma usually benign

• Can be well differentiated to pleomorphic

• Deep blue cytoplasm, perinuclear clear area, occ. eosinophilic borders

• Round, eccentric nucleus

Describe the features of lymphomas

• Round cells w/ high nucleus:cytoplasm ration

• Large lymphos (larger than neutros) predom

• Monomorphic p

  

  opulation

What breeds are predisp to mast cell tumours?

• Boxer

• Pug

• Boston terrier

How do mast cell tumours appear appear cytologically?

• Mast cells —> individually or in small groups

• Tumour cells vary in degree of granularity and nuclear atypia —> poor granulation can be due to poor differentiation (more aggressive)

• Eosinophils usually

How should you stain a mast cell tumour?

Not with Diff quick (will lose granules)

• Toluidine Blue stain

• Submit some unstained slides

What are the features of endocrine/ neuroendocrine tumours?

• Naked nuclei in lakes of cytoplasm

  • many free nuclei present & indistinct cytoplasmic borders

• Round to polygonal cells

• Samples usually highly cellular

• Nuclei = round to indented (none to minimal anisokaryosis)

Give some examples of endocrine/ neuroendocrine tumours

• Thyroid carcinoma

• Phaechromocytoma

What is the difference between these

Don't confuse them

What are the features of a thyroid carcinoma?

• Usually blood in background

• Cells in clusters mixed w/ variable numbers of naked nuclei in background

• Dark blue to black cytoplasmic pigment (tyrosine granules) sometimes intact cells

• Extracellular colloid (pink material) may be seen (arrow)

• Minimal atypia —> need histopath for degree of malig

What are the features of pheochromocytoma?

• Tumour of chromaffin cells of adrenal medulla

• Clin symptoms due to catecholamine release from tumout

• Naked nuclei against background of pale basophilic cytoplasma

• Both benign & malig poss

  • Features of malig unreliable in predicting biological behaviour

Summary of tumour types

What neoplasia is being shown here?

Melanoma

• (Dark brown to black, circumscribed, raised, dome-shaped usually hairless mass)

• Pleomorphic (epitheliod to fusiform to round)

  • Fine black-green granules masking nucleus, large single nucleolus

• May have sparse granulation

What are the general vs specific cell tumour types?

What is this type of neoplasia?

Mesenchymal