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Medicine 2 - 08 Breast Cancer > 9 Tumour pathology > Flashcards

9 Tumour pathology Flashcards

1
Q

What is a neoplasm?

A

A neoplasm is an abnormal mass of tissue:

  • the growth of which exceeds and is uncoordinated with that of the normal tissues
  • persists in the same excessive manner after cessation of the stimuli which evoked change

This abnormal mass is purposeless, preys on the host, and virtually autonomous

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2
Q

Give two fundamental features of neoplasms

A
  • Unregulated growth

- Clonal genetic defects

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3
Q

What are the features distinguishing benign versus malignant tumors

A
  • Degree of differentiation
  • Anaplasia
  • Rate of growth
  • Local invasion (benign)
  • Metastasis (malignant)
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4
Q

Describe differentiation in relation to tumors

A

Differentiation - the extent to which neoplastic cells resemble normal tissue morphologically and functionally

  • Well-differentiated - closely resembles tissue of origin
  • Poorly differentiated - unspecialized, little resemblance to the tissue of origin
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5
Q

Describe anaplasia in relation to tumors

A

Anaplasia - lack of differentiation

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6
Q

How can anaplasia arise

A

can be due to:

  • Abnormal nuclei
  • high nuclei:cytoplasmic ratio
  • hyperchromatic nuclei (duplicating DNA)
  • clumped chromatin
  • prominent nucleoli

Anaplastic nuclei may have multiple copies of chromosomes and therefore more DNA

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7
Q

Describe pleomorphism in relation to tumors

A
  • Variation in size and shape of cells
    and nuclei
  • abnormal mitotic figures
    (in normal tissue cell are usually uniform
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8
Q

Describe benign neoplasms

A

They are cohesive, expansile, well-demarcated masses, do not invade or infiltrate surrounding normal tissue
- (can push local structures, put pressure on them - but no invasion)

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9
Q

Give some features of benign neoplasms

A
  • Usually progressive and slow growth (can be seen on clinical and radiological examination) may come to standstill or regress
  • Well-differentiated; a structure sometimes typical of tissue of origin
  • Do not metastasize
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10
Q

Give some examples of benign neoplasms

A
  • Adenoma
  • Polyp
  • Brain tumors
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11
Q

Describe malignant neoplasms

A
  • Locally invasive, infiltrating surrounding tissue; sometimes maybe misleadingly cohesive and expansive

Locally advanced malignant tumors are fixed to adjacent structures and not mobile

On clinical examination - the tumor may be palpated

  • May grow slowly or rapidly
  • Some lack of differentiation (anaplasia); structures often atypical
  • Metastasis - frequent - more likely with large undifferentiated primary tumors
    > can spread through cavities, lymphatics, hematogenous (live, lung)
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12
Q

How can a neoplasm be determined to be benign or malignant on examination

A
  • One feature of malignant neoplasm is the fixation of the mass to deep tissues
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13
Q

What are neoplasms composed of?

A

Composed of proliferative neoplastic cells - with non-neoplastic stroma of connective tissue and blood vessels

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14
Q

What is a mixed tumor?

A

Neoplasms with more than one cell type but arising from one germ cell layer

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15
Q

What is a teratoma?

A

Neoplasms with more than one cell type and arising from more than one germ layer

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16
Q

What are neoplasms ending in -blastoma

A

They resemble primitive embryonic tissue, which are often paediatric neoplasms

(e.g. Retinoblastoma, neuroblastoma)

17
Q

What is tumor grade?

A

It is a histological parameter that quantifies the degree of differentiation

  • Well-differentiated = low-grade tumour resemble mature normal cells of the tissue of origin
  • Poorly differentiated = high-grade tumour shows little resemblance to the tissue of origin

Many cancers are graded as:

  • 2 (high/low)
  • 3-tier (1,2,3) system
18
Q

How is tumour grade used/why is it useful?

A

Many tumours show varying grades of differentiation

  • grade can predict tumour behaviour
  • and response to therapy
19
Q

State some limitations on tumour grading

A
  • Many tumours show intermediate differentiation
  • Sampling error in small biopsies
  • Interobserver variation for assessment of grade (microscope - subjective)
20
Q

Describe the TNM tumour staging system

A

TNM stage

  • Information on the size of tumour, extent of invasion, lymph node enlargement, di stant metastasis
  • Important in planning appropriate treatment, prognosis, research and guidelines
21
Q

What are the clinical manifestations of cancer?

A

Cancer can cause illness by:
- Local invasion and impingement on local structures
- Ulcerations, bleeding, and infection
- Cachexia
- Paraneoplastic processes
> e.g. SVC syndrome, haemoptysis, microcytic anaemia, PR bleeding, melaena, infection, cachexia [loss of weight] - increased basal metabolic rate - loss of muscle and fat etc.

22
Q

Describe the aetiology of cancer

A

Environmental causes:

  • chemicals
  • infectious agents
  • radiation

Hereditary causes

Carcinogens

23
Q

Describe carcinogens

A

Carcinogens - an external agent that increases the incidence of malignant neoplasms, reduce their latency, or increases their severity or multiplicity

24
Q

Describe how chemical carcinogens may work

A

There are 2 steps: initiation and promotion

  • An initiating carcinogenic agent irreversibly damages cell DNA (mutagenic) to start the process
  • A promoting agent (which may be the same as a carcinogen) then acts reversibly to cause the proliferation of a neoplastic cell clone
    > but there seems to be a ‘dose threshold concentration of promoter below which neoplasm will not occur
25
Q

Describe chemical carcinogens (make-up)

A

Many chemical carcinogens are highly reactive electrophiles (have electron-deficient atoms) that can react with nucleophilic (electron-rich) sites in the cell
- including DNA, RNA, and protein

Direct carcinogens (direct-acting alkylating agents)

Indirect carcinogens (aka procarcinogens) - metabolite is the active carcinogen

26
Q

Give some different types of procarcinogens

and also explain how they can be metabolically activated

A

Types of procarcinogens:

  • Polycyclic aromatic hydrocarbons: the most potent carcinogen, produced in the combustion of tobacco, can cause lung and bladder cancers
  • Tobacco smoke contains over 4000 chemical compounds

Metabolic activation of procarcinogens:
- Metabolized + activated by Cytochrome P-450 dependent monooxygenase

27
Q

Explain the concept of occupational cancers (and what may cause them to arise)

A
  • Arsenic (metal smelting, herbicide)
  • Asbestos (in fire-resistant textiles, brake lining, tiles) - Lung and skin cancer
  • Benzene (light oil, paint, and dry cleaning) - Lung, mesothelioma, and GI tract cancers
  • Vinyl chloride (refrigerant and plastics) - leukaemia, Hodgkin lymphoma
  • Angiosarcoma and liver cancer
28
Q

Describe how radiation can lead to cancer

A
  • UV light - skin cancers
  • Ionising radiation (X-rays, gamma rays)

Leukaemia, thyroid, breast, and many other cancers

29
Q

Describe some infectious agent carcinogens

A

Viruses:

  • HPV - colorectal cancer
  • Epstein-Barr virus - lymphoma, nasopharyngeal carcinoma
  • Hep B and C viruses - liver cancers

Bacteria:
- Heliobacter pylori - stomach cancer

Parasites:
- Schistosoma haematobium - bladder cancer

30
Q

Describe how cultural and lifestyle habits can contribute to developing cancer

A
  • Tobacco smoke - lung and respiratory tract, kidney, bladder, and pancreas cancer
  • Ethanol - liver, upper aerodigestive tract cancers
  • Betel quid - mouth cancer
  • Smokeless tobacco - mouth cancer

Obestiy - colon, endometrial, breast cancer

Medicine 2 - 08 Breast Cancer (8 decks)

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