Neoplasia 1 Flashcards
Define neoplasia
Abnormal mass of tissue, growth of which exceeds and is uncoordinated with that of normal tissues and persists after cessation of initiating stimulus.
Benign: confined to site of origin
Malignant: invasion and metastasis
Describe the difference between benign and malignant neoplasms
Give examples of each
Benign:
- Cells grow as a compact mass and remain at their site of origin
- E.g. lipoma
Malignant:
- Growth of cells is uncontrolled
- Cells can invade surrounding tissue and spread to distant tissues
- Malignant tumour = cancer
What are the two basic components of tumours?
Parenchyma:
- Neoplastic cells
- Determines the biological behaviour of the neoplasm and the name of the neoplasm.
Reactive stroma:
- Connective tissue, blood vessels, supporting tissue
- Determines rate of growth of tumour.
How are neural tumours named?
Benign:
- Nerve: neuroma
- Nerve sheath: schwannoma
Malignant:
- Nerve: neurofibrosarcoma
- Nerve sheath: malignant peripheral NST
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How are cartilaginous tumours named?
Benign: Chondroma
Malignant: Chondrosarcoma
What are the key macroscopic, microscopic and behaviour differences between benign and malignant tumours?
Behaviour:
Benign:
- No invasion
- No metastasis
- Retain function
- Growth rate- variable but often slow
Malignant:
- Invasion, infiltration
- Metastasis
- Loss of function
- Variable growth rate- often higher than benign tumours
Macroscopic features:
Benign:
- Well defined edge
- Can be encapsulated
Malignant:
- Poorly defined edge
- Haemorrhage
- Necrosis
Microscopic features:
- Differentiation
- Malignant: poorly differentiated
- Benign: well differentiated
- Organisation
- Benign: organised
- Malignant: not organised
- Growth pattern
- Benign: expansile, cohesive growth
- Malignant: local invasion beyond normal boundary
- Pleomorphism:
- Benign: minimal
- Malignant: variable
- Nuclear to cytoplasmic ratio:
- Benign: Normal (1:4-1:6)
- Malignant: increased (1:1)
- Mitotic count
- Benign: low count, normal mitoses
- Malignant: low-high count, abnormal mitoses
- Polarity (orientation):
- Benign: not disturbed
- Malignant: lost cell to ECM, adhesion disturbed, nucleus can be located anywhere
- Nuclear morphology:
- Benign: round/oval with smooth outline and chromatin, +/- nucleoli
- Malignant: bizarre in shape and size; hyperchromatic; course; clumped chromatin; prominent (possible multiple) nucleoli
Outline the differences in differentiation/anaplasia between benign and malignant tumours
Benign:
- Well differentiated
- Structure sometimes typical of tissue of origin
Malignant:
- Some lack of differentiation
- Structure usually atypical of tissue of origin
What are the differences in organisation between benign and malignant tumours?
Benign: well organised
Malignant: not organised
What are the differences in growth pattern between benign and malignant tumours?
Benign: expansile cohesive growth
Malignant: Local invasion beyond normal boundary
What are the differences in pleomorphism between benign and malignant tumours?
Benign: minimal
Malignant: minimal to marked, often variable
What are the differences in nuclear to cytoplasmic ratio between benign and malignant tumours?
Benign: Normal (1:4 - 1:6)
Malignant: increased (1:1)
What are the differences in mitotic count between benign and malignant cells?
Benign: low, normal mitoses
Malignant: low to high, abnormal mitoses
What are the differences in polarity between benign and malignant cells?
Benign: Not disturbed
Malignant: Lost cell to ECM adhesion disturbed, nucleus can be located anywhere
What are the differences in nuclear morphology between benign and malignant cells?
Benign: Round to oval with smooth outline and chromatin, nucleoli +/-
Malignant: Bizarre in shape and size; hyperchromatic, coarse, clumped chromatin; prominent nucleoli, may be multiple.
How are malignant neoplasms graded?
What does grading mean?
Grading: how differentiated the cells are to the tissue of origin (how similar).
- Grade 1: Well differentiated
- Grade 2: Moderately differentiated
- Grade 3: Poorly differentiated
- Undifferentiated: total lack of differentiation and abscence of specialisation
Define metastasis
Spread of a tumour to sites which are physically discontinuous with the primary tumour.
Only occurs in malignant tumours
What macroscopic and microscopic features increase the chance of tumour metastasising?
Lack of differentiation
Local invasion
Rapid growth
Larger size
Name some infrequently metastasising neoplasms
Glioma
Basal cell carcinoma
What are the possible pathways of spread of metastatic cancer?
Which types of neoplasm are more common with each pathway?
Which organs are most frequently involved?
Blood vessels (haematogenous):
- Typically sarcomas, also carcinomas
- Venous > arterial, capillary beds
- Liver and lung most frequently involved (portal system → liver, systemic circulation → lung)
- Prostate and thyroid: cancers in close proximity to vertebral column→ vertebral metastasis
Lymphatics:
- Carcinomas (less commonly sarcomas)
- Breast carcinoma → axillary lymph node spread
- Lung carcinoma → tracheobronchial and mediastinal lymph nodes
Body cavities (transceolomic) and surfaces:
- Peritoneal, pleural, pericardial, subarachnoid, joint spaces
What is a sentinal lymph node?
The first lymph node in a regional lymphatic basin that receives lymph flow from the primary tumour.
What is the molecular procedure for the sentinal lymph node
One-step nucleic acid amplification (OSNA) assay for the intraoperative assessment of sentinal lymph node metastases in breast cancer.
Measures cytokeratin 19 (CK19) mRNA copy number.
High sensitivity and specificity.
Name some common malignant tumours in paediatrics
- Kidney: Wilms tumour
- Eye: retinoblastoma
- Liver: hepatoblastoma
- CNS: meduloblastoma
- Blood: leukaemia
- Lymph: lymphoma
- Connective tissue and bone: neuroblastoma, rhabdomyosarcoma, osteogenic sarcoma, Ewing sarcoma
What are the precursor lesions for neoplasia?
Metaplasia: replacement of one type of cell with another type (associated with tissue damage, repair, regeneration)
Dysplasia: disordered growth: loss of uniformity of individual cells. Loss in architectural orientation.
In-situ carcinoma/ in-situ malignancy
What is the single most important precursor lesion and risk factor for oesophageal adenocarcinoma?
Barrett’s oesophagus
