2 - Neoplasia Flashcards
Neoplasm
An abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissues, and persists in the same excessive manner after apparent cessation of the stimuli which evoked the change
What does neoplasia exclude
- Hyperplasia
- Hypertrophy
- Inflammation
Two basic components of neoplasm
- Clonal cells from one type of progenitor (range from mature to immature primitive cells)
- Reactive stroma made up of connective tissue, blood vessels, and inflammatory cells
Classification of tumours
- Histogenetic (morphology, molecular)
- Aetiological
- Therapeutic biomarkers
Benign
Will remain localised (e.g. naevus)
Malignant
Invasion (locally or spread)
Molecular subtype of colorectal cancer with highest mutation count
CMS1
Classification by histogenesis
- Epithelium
- Mesenchyme (stroma/connective tissue elements)
- Blood and related cells
- Special cells (melanocytes, germ cells)
Tissue type of origin + “oma”
- Benign
- e.g. Lipoma
Cell/tissue type + “Carcinoma”
- Malignant
- E.g. adenocarcinoma (adeno: relating to glands)
Cell/tissue type + “Sarcoma”
- Malignant
- E.g. liposarcoma (adipocyte-like cells)
Examples of sarcomas
- Osteosarcoma (background mineralised bone)
- Leiomyosarcoma (smooth muscle fibres)
Differentiation
The extent to which neoplastic parenchymal cells resemble the corresponding normal parenchymal cells, both morphologically and functionally
Anaplasia
Lack of differentiation
Morphologic changes associated with anaplasia
- Variation in size and shape
- Atypical mitotic figures, sometimes producing tripolar or multipolar spindles (reflects higher proliferative activity of parenchymal cells)
- Loss of polarity (anaplastic cells grow in disorganised fashion)
- Abnormal cellular morphology
Examples of abnormal cellular morphology of anaplasia
- Disproportionately large for cell
- Nuclear to cytoplasm ratio 1:1 instead of 1:6
- Chromatin clumped and distributed along nuclear membrane
- Large nucleoli
Metaplasia
- The replacement of one type of cell with another type
- Usually in association with tissue damage, repair, and regeneration
Metaplasia example
- Normally squamous cells line the oesophagus
- In process of metaplasia, these are replaced by columnar intestinal-type cells
- Leads to barrett oesophagus
- Precursor lesion increases risk of oesophageal carcinoma
Dysplasia
- Disordered growth, often occurs in background metaplastic epithelium
- Architecture of the epithelium becomes disorderly
- Often found adjacent to foci of invasive carcinoma
Does dysplasia lead to cancer?
- Dysplasia does not necessarily progress to cancer
- Once the tumour cells breach the basement membrane, the tumour is said to be invasive.
- High grade dysplasia = carcinoma in situ (
What is nottingham grading system of breast cancer based on
- Tubule formation
- Nuclear grade
- Mitotic rate
Gleason scoring system
- For prostate cancer
- Based on biopsy
- Both primary and secondary pattern of tissue organisation identified
- Primary is most common tissue pattern seen in tumour, secondary is next most common
Major impediment in the treatment of cancer
By the time a solid tumor is clinically detected, it has often completed a major portion of its life span.
Formation of metastases
- Penetrate the basement membranes
- Movement through extracellular matrix
- Penetration of vascular channels
- Survival/arrest in the circulation
- Exit to new tissue sites
- Survival and growth as metastasis evoking angiogenesis
Common sites for metastasis
- Bone
- Liver
- Brain
- Lung
- Lymph nodes
Spread of carcinoma
- Local direct invasion
- Intraepithelial spread
- Lymphatic dissemination
- Haematogenous dissemination
- Spread across body cavities (e.g. Pleural)
- Biopsy site (e.g. mesothelioma)
Effects of metastasis
- Destructive growth in vital organs (–> death)
- Significant morbidity as well as mortality
TNM staging
- T: Tumour (size, local spread)
- N: Nodal status (number, groups, size, etc)
- M: Metastasis
