Week 9-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
How can benign or malignant tumours be differentiated?
Behaviour:
- Invasion
- Metastasis
- Retain or lose function
- Growth rate
Macroscopic features:
- Well or ill defined edge
- Haemorrhagic?
- Necrosis?
Microscopic features:
- Differentiation
- Organisation
- Growth pattern
- Pleomorphism
- Nuclear to cytoplasmic ratio
- Mitotic count
- Polarity (orientation)
- Nuclear morphology
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