Tumours: behaviour and spread Flashcards
What do benign tumours look like in solid organs
Spherical mass because they grow evenly in all directions
How do benign tumours on epithelial surfaces grow
IN direction of least resistance (they are called papillomas because of their papillary shape)
What do malignant tumours look like
Irregular in outline and have indistinct edges because they expand and infiltrate adjacent tissue
How do we tell if a tumour is benign or malignant in its early stages
perform a biopsy to assess the cytological characteristic of the tumour cells
What are the cytological characteristics of malignancy
- Pleomorphism- cellular/nuclear
- High nucleus to cytoplasm ratio
- Nuclear hyperchromatism
- High mitotic count
- Abnormal mitoses
what is cellular pleomorphism
Variation in size and shape of cells in tumour
what is nuclear pleomorphism
Variation in shape and size of nuclei in tumour cells
What is nuclear hyperchromatism
Very dark staining nuclei due to increased nuclear DNA
What is high mitotic count
Increased numbers of cells in mitosis, including abnormal mitotic forms
How can you tell if there is abnormal mitosis
Nucleus is in a Y shape
What is dysplasia
Abnormal cell structure
Does dysplasia in tumour cells always mean invasive behaviour ?
Usually, but not always
What is carcinoma-in-situ or intra-epithelial neoplasia
Dysplasia in an epithelium that does not show invasion across the epithelial basement membrane
What happens to dysplasia?
Sometimes it disappears (regresses) but more often, it turns into invasive malignancy
How does a malignant tumour spread lymphatically
It invades into the lumen of a lymphatic vessel and bits can break off and pass to the lymph nodes draining the area
What happens to a tumour when in the lymph node
Gets trapped in the sub scapular sinus and there, the tumour cells proliferate until the whole node is replaced by tumour
How do tumours spread in blood stream
Invades the wall of a small vessel, clumps of tumour cells break off and pass in the circulation until they meet a vessel too small to let It pass and then they grow to produce a distant metastasis
Where are secondary deposits in bone usually from
Breast Bronchus/lung Kidney Thyroid Prostate
How can benign tumours cause illness and death by
Bleeding Pressure on adjacent vital structures Obstruction Hormone secretion (eg pituitary adenoma) Conversion to a malignant tumour
